Furosemide-induced ototoxicity

Randomized controlled trial of urinE chemiStry guided aCute heArt faiLure treATmEnt (ESCALATE): Rationale and design

Diuresis to achieve decongestion is a central aim of therapy in patients hospitalized for acute decompensated heart failure (ADHF). While multiple clinical trials have investigated initial diuretic strategies for a designated period of time, there is a paucity of evidence to guide diuretic titration strategies continued until decongestion is achieved. The use of urine chemistries (urine sodium and creatinine) in a natriuretic response prediction equation accurately estimates natriuresis in response to diuretic dosing, but a randomized clinical trial is needed to compare a urine chemistry-guided diuresis strategy with a strategy of usual care. The urinE chemiStry guided aCute heArt faiLure treATmEnt (ESCALATE) trial is designed to test the hypothesis that protocolized diuretic therapy guided by spot urine chemistry through completion of intravenous diuresis will be superior to usual care and improve outcomes over the 14 days following randomization. ESCALATE will randomize and obtain complete data on 450 patients with acute heart failure to a diuretic strategy guided by urine chemistry or a usual care strategy. Key inclusion criteria include an objective measure of hypervolemia with at least 10 pounds of estimated excess volume, and key exclusion criteria include significant valvular stenosis, hypotension, and a chronic need for dialysis. Our primary outcome is days of benefit over the 14 days after randomization. Days of benefit combines patient symptoms captured by global clinical status with clinical state quantifying the need for hospitalization and intravenous diuresis. CLINICAL TRIAL REGISTRATION: NCT04481919.

Choosing the right chronic medication for hemodialysis patients. A short ABC for the dialysis nephrologist

BACKGROUND

Adapting drug treatments for patients on hemodialysis with multiple chronic pathologies is a complex affair. When prescribing a medication, the risk-benefit analysis usually focuses primarily on the indication of the drug class prescribed. However, the pharmacokinetics of the chosen drug should also be taken into account. The purpose of our review was to identify the drugs to be favored in each therapeutic class, according to their safety and pharmacokinetic profiles, for the most common chronic diseases in patients on chronic hemodialysis.

METHODS

We conducted a narrative review of the literature using Medline and Web of Science databases, targeting studies on the most commonly-prescribed drugs for non-communicable diseases in patients on chronic hemodialysis.

RESULTS

The search identified 1224 articles, 95 of which were further analyzed. The main classes of drugs included concern the cardiovascular system (anti-hypertensives, anti-arrhythmics, anti-thrombotics, hypocholesterolemics), the endocrine and metabolic pathways (anti-diabetics, gastric anti-secretory, anticoagulant, thyroid hormones, anti-gout) and psychiatric and neurological disorders (antidepressants, anxiolytics, antipsychotics and anti-epileptics).

CONCLUSION

We report on the most often prescribed drugs for chronic pathologies in patients on chronic hemodialysis. Most of them require adaptation, and in some cases one better alternative stands out among the drug class. More pharmacokinetic data are needed to define the pharmacokinetics in the various dialysis techniques.

Identifying targets to prevent aminoglycoside ototoxicity

Aminoglycosides are potent antibiotics that are commonly prescribed worldwide. Their use carries significant risks of ototoxicity by directly causing inner ear hair cell degeneration. Despite their ototoxic side effects, there are currently no approved antidotes. Here we review recent advances in our understanding of aminoglycoside ototoxicity, mechanisms of drug transport, and promising sites for intervention to prevent ototoxicity.

Diuretic therapy in congestive heart failure

In heart failure, fluid overload is a major pathological mechanism leading to vascular congestion, pulmonary congestion and elevated jugular venous pressures. Diuretics play a significant role in the management of patients with congestive heart failure. It is used to relieve the congestive symptoms of heart failure. However, the appropriate use of diuretics remains challenging due to various complications like electrolyte abnormalities, worsening renal function and diuretic resistance. This has prompted towards the search of safer and effective alternatives. This review evaluates the use of diuretics in congestive heart failure and discusses the complications of different types of diuretics, which is essential for successful management of congestion in patients with heart failure and hence to optimise the outcome for the patients.

Hypertension Associated With Hearing Loss and Tinnitus Among Hypertensive Adults at a Tertiary Hospital in South Africa

Introduction

Hypertension is one of the leading causes of morbidity and mortality worldwide, and has been associated with target organ damage. Effects of hypertension on the auditory system are varied and requires further investigation. This study aimed to investigate the association between hypertension and auditory deficits (hearing loss and tinnitus).

Methods

This study employed a cross-sectional study including 106 (54.7% female) hypertensive adults aged 18–55 years, and 92 (52.2% female) non-hypertensive sex- and age-matched adults residing in South Africa. A data extraction sheet was used to obtain hypertension information from participants' medical files, and to subjectively obtain tinnitus status and characteristics among participants. Participants' hearing sensitivity—including extended high frequencies (EHF)—were measured using a diagnostic audiometer. The χ2 test determined the difference in auditory deficit prevalence between the study groups. Logistic regression was used to identify predictor variables associated with auditory deficits in the hypertensive group.

Results

A hearing loss prevalence of 37.4% among hypertensive adults compared to 14.1% among the non-hypertensive group (P = 0.000, χ2 = 14.00) was found. The EHF pure-tone average among the hypertensive group was 44.1 ± 19.2 dB HL, and 20.0 ± 18.3 dB HL among the control group. Bilateral mild sensorineural hearing loss was the most common type of hearing loss among hypertensive adults. A higher prevalence of tinnitus (41.5%) was found in the hypertensive group compared to the control group (22.8%) (P = 0.008, χ2 = 7.09). In this study, 30.3% of hypertensive adults had tinnitus without hearing loss compared to 17.7% non-hypertensive adults. Factors associated with hearing loss included being between 50 and 55 years [adjusted Odds Ratio (AOR) = 3.35; 95% Confidence Interval (CI): 1.32–8.50; P = 0.011], having grade 2 hypertension (AOR = 4.18; 95% CI: 1.02–17.10; P = 0.048), and being on antihypertensive medication (AOR = 3.18; 95% CI: 1.02–9.87; P = 0.045). Tinnitus was associated with grade 3 hypertension (AOR = 3.90; 95% CI: 1.12–12.64; P = 0.033).

Conclusions

Our study showed that hypertensive adults had a higher proportion of hearing loss and tinnitus compared to non-hypertensive adults. Findings suggest an association between hypertension and auditory deficits, demonstrating a need for integration of hearing healthcare services for hypertension management.

Long-term follow-up of high-risk neuroblastoma survivors treated with high-dose chemotherapy and stem cell transplantation rescue

Intensive treatments including high-dose chemotherapy (HDC) with autologous stem cell rescue have improved high-risk neuroblastoma (HRNB) survival. We report the long-term health status of 145 HRNB survivors, alive and disease-free 5 years post HDC. Median follow-up was 15 years (range = 5-34). Six patients experienced late relapses, 11 developed second malignant neoplasms (SMNs), and 9 died. Event-free and overall survivals 20 years post HDC were 82% (95% CI = 70%-90%) and 89% (78%-95%), respectively. Compared with the French general population, the standardized mortality ratio was 19 (95% CI = 8.7-36.1; p < 0.0001) and the absolute excess risk was 37.6 (19.2-73.5). Late effects were observed in 135/145 patients (median = 3 events/patient); 103 had at least one severe event. SMNs arose at a median of 20 years post HDC and included carcinoma (n = 5), sarcoma (2), acute myeloid leukemia (2), melanoma (1), and malignant glioma (1). Non-oncologic health events included dental maldevelopment (60%), severe hearing loss (20% cumulative probability at 15 years), hepatic focal nodular hyperplasia (14%), thyroid (11%), cardiac (8%), and renal (7%) diseases and growth retardation (height-for-age z-score ≤ -2 for 21%). Gonadal insufficiency was near-universal after busulfan (40/43 females, 33/35 males). Severe late effects are frequent and progressive in HRNB survivors needing systematic very long-term follow-up.

Contribution of Uptake and Efflux Transporters to Oral Pharmacokinetics of Furosemide

Furosemide is a widely used diuretic for treating excessive fluid accumulation caused by disease conditions like heart failure and liver cirrhosis. Furosemide tablet formulation exhibits variable pharmacokinetics (PK) with bioavailability ranging from 10 to almost 100%. To explain the variable absorption, we integrated the physicochemical, in vitro dissolution, permeability, distribution, and the elimination parameters of furosemide in a physiologically-based pharmacokinetic (PBPK) model. Although the intravenous PBPK model reasonably described the observed in vivo PK data, the reported low passive permeability failed to capture the observed data after oral administration. To mechanistically justify this discrepancy, we hypothesized that transporter-mediated uptake contributes to the oral absorption of furosemide in conjunction with passive permeability. Our in vitro results confirmed that furosemide is a substrate of intestinal breast cancer resistance protein (BCRP), multidrug resistance-associated protein 4 (MRP4), and organic anion transporting polypeptide 2B1 (OATP2B1), but it is not a substrate of P-glycoprotein (P-gp) and MRP2. We then estimated the net transporter-mediated intestinal uptake and integrated it into the PBPK model under both fasting and fed conditions. Our in vitro data and PBPK model suggest that the absorption of furosemide is permeability-limited, and OATP2B1 and MRP4 are important for its permeability across intestinal membrane. Further, as furosemide has been proposed as a probe substrate of renal organic anion transporters (OATs) for assessing clinical drug-drug interactions (DDIs) during drug development, the confounding effects of intestinal transporters identified in this study on furosemide PK should be considered in the clinical transporter DDI studies.

Predictors of Faster Decline of Residual Renal Function in Taiwanese Peritoneal Dialysis Patients

⋄ Objective

Loss of residual renal function (RRF) in peritoneal dialysis (PD) patients is a powerful predictor of mortality. The present study was conducted to determine the predictors of faster decline of RRF in PD patients in Taiwan.

⋄ Methods

The study enrolled 270 patients starting PD between January 1996 and December 2005 in a single hospital in Taiwan. We calculated RRF as the mean of the sum of 24-hour urea and creatinine clearance. The slope of the decline of residual glomerular filtration rate (GFR) was the main outcome measure. Data on demographic, clinical, laboratory, and treatment parameters; episodes of peritonitis; and hypotensive events were analyzed by Student t-test, Mann–Whitney U-test, and chi-square, as appropriate. All variables with statistical significance were included in a multivariate linear regression model to select the best predictors ( p < 0.05) for faster decline of residual GFR.

⋄ Results

All patients commencing PD during the study period were followed for 39.4 ± 24.0 months (median: 35.5 months). The average annual rate of decline of residual GFR was 1.377 ± 1.47 mL/min/m2. On multivariate analysis, presence of diabetes mellitus ( p < 0.001), higher baseline residual GFR ( p < 0.001), hypotensive events ( p = 0.001), use of diuretics ( p = 0.002), and episodes of peritonitis ( p = 0.043) independently predicted faster decline of residual GFR. Male sex, old age, larger body mass index, and presence of coronary artery disease or congestive heart failure were also risk factors on univariate analysis.

⋄ Conclusions

Our results suggested that diabetes mellitus, higher baseline residual GFR, hypotensive events, and use of diuretics are independently associated with faster decline of residual GFR in PD patients in Taiwan.

Intravenously delivered aminoglycoside antibiotics, tobramycin and amikacin, are not ototoxic in mice

Many drugs on the World Health Organization's list of critical medicines are ototoxic, destroying sensory hair cells within the ear. These drugs preserve life, but patients can experience side effects including permanent hearing loss and vestibular dysfunction. Aminoglycoside ototoxicity was first recognised 80 years ago. However, no preventative treatments have been developed. In order to develop such treatments, we must identify the factors driving hair cell death. In vivo, studies of cell death are typically conducted using mouse models. However, a robust model of aminoglycoside ototoxicity does not exist. Previous studies testing aminoglycoside delivery via intraperitoneal or subcutaneous injection have produced variable ototoxic effects in the mouse. As a result, surgical drug delivery to the rodent ear is often used to achieve ototoxicity. However, this technique does not accurately model clinical practice. In the clinic, aminoglycosides are administered to humans intravenously (i.v.). However, repeated i.v. delivery has not been reported in the mouse. This study evaluated whether repeated i.v. administration of amikacin or tobramycin would induce hearing loss. Daily i.v. injections over a two-week period were well tolerated and transient low frequency hearing loss was observed in the aminoglycoside treatment groups. However, the hearing changes observed did not mimic the high frequency patterns of hearing loss observed in humans. Our results indicate that the i.v. delivery of tobramycin or amikacin is not an effective technique for inducing ototoxicity in mice. This result is consistent with previously published reports indicating that the mouse cochlea is resistant to systemically delivered aminoglycoside ototoxicity.

Different infusion durations for preventing platinum-induced hearing loss in children with cancer

BACKGROUND

Platinum-based therapy, including cisplatin, carboplatin or oxaliplatin, or a combination of these, is used to treat a variety of paediatric malignancies. Unfortunately, one of the most important adverse effects is the occurrence of hearing loss or ototoxicity. In an effort to prevent this ototoxicity, different platinum infusion durations have been studied. This review is the third update of a previously published Cochrane Review.

OBJECTIVES

To assess the effects of different durations of platinum infusion to prevent hearing loss or tinnitus, or both, in children with cancer. Secondary objectives were to assess possible effects of these infusion durations on: a) anti-tumour efficacy of platinum-based therapy, b) adverse effects other than hearing loss or tinnitus, and c) quality of life.

SEARCH METHODS

We searched the electronic databases Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library 14 November 2019), MEDLINE (PubMed) (1945 to 14 November 2019) and Embase (Ovid) (1980 to 14 November 2019). In addition, we handsearched reference lists of relevant articles and we assessed the conference proceedings of the International Society for Paediatric Oncology (2009 up to and including 2019) and the American Society of Pediatric Hematology/Oncology (2014 up to and including 2019). We scanned ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP; apps.who.int/trialsearch) for ongoing trials (both searched on 4 November 2019).

SELECTION CRITERIA

Randomised controlled trials (RCTs) or controlled clinical trials (CCTs) comparing different platinum infusion durations in children with cancer. Only the platinum infusion duration could differ between the treatment groups.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, 'Risk of bias' assessment and GRADE assessment of included studies, and data extraction including adverse effects. Analyses were performed according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified one RCT and no CCTs; in this update no additional eligible studies were identified. The RCT (total number of children = 91) evaluated the use of a continuous cisplatin infusion (N = 43) versus a one-hour bolus cisplatin infusion (N = 48) in children with neuroblastoma. For the continuous infusion, cisplatin was administered on days one to five of the cycle, but it is unclear if the infusion duration was a total of five days. Risk of bias was present. Only results from shortly after induction therapy were provided. No clear evidence of a difference in hearing loss (defined as asymptomatic and symptomatic disease combined) between the different infusion durations was identified as results were imprecise (risk ratio (RR) 1.39, 95% confidence interval (CI) 0.47 to 4.13, low-quality evidence). Although the numbers of children were not provided, it was stated that tumour response was equivalent in both treatment arms. With regard to adverse effects other than ototoxicity, we were only able to assess toxic deaths. Again, the confidence interval of the estimated effect was too wide to exclude differences between the treatment groups (RR 1.12, 95% CI 0.07 to 17.31, low-quality evidence). No data were available for the other outcomes of interest (i.e. tinnitus, overall survival, event-free survival and quality of life) or for other (combinations of) infusion durations or other platinum analogues.

AUTHORS' CONCLUSIONS

Since only one eligible RCT evaluating the use of a continuous cisplatin infusion versus a one-hour bolus cisplatin infusion was found, and that had methodological limitations, no definitive conclusions can be made. It should be noted that 'no evidence of effect', as identified in this review, is not the same as 'evidence of no effect'. For other (combinations of) infusion durations and other platinum analogues no eligible studies were identified. More high-quality research is needed.

Predicting the Need for a Tier II Ototoxicity Study From Early Renal Function Data

History has established that many drugs, such as the antibiotics, chemotherapies, and loop diuretics, are capable of inducing both nephrotoxicity and ototoxicity. The exact mechanisms by which cellular damage occurs remain to be fully elucidated. Monitoring the indices of renal function conducted in the Food and Drug Administration's prescribed set of early investigational new drug (IND)-enabling studies may be the first signs of ototoxicity properties of the new drug candidate. In developing improved and efficacious new molecular entities, it is critically necessary to understand the cellular and molecular mechanisms underlying the potential ototoxic effects as early in the drug development program as possible. Elucidation of these mechanisms will facilitate the development of safe and effective clinical approaches for the prevention and amelioration of drug-induced ototoxicity prior to the first dose in man. Biomarkers for nephrotoxicity in early tier I or tier II nonclinical IND-enabling studies should raise an inquiry as to the need to conduct a full auditory function assay early in the game to clear the pipeline with a safer candidate that has a higher probability of continued therapeutic compliance once approved for distribution.

Medical interventions for the prevention of platinum-induced hearing loss in children with cancer

BACKGROUND

Platinum-based therapy, including cisplatin, carboplatin, oxaliplatin or a combination of these, is used to treat a variety of paediatric malignancies. One of the most significant adverse effects is the occurrence of hearing loss or ototoxicity. In an effort to prevent this ototoxicity, different otoprotective medical interventions have been studied. This review is the third update of a previously published Cochrane Review.

OBJECTIVES

To assess the efficacy of medical interventions to prevent hearing loss and to determine possible effects of these interventions on antitumour efficacy, toxicities other than hearing loss and quality of life in children with cancer treated with platinum-based therapy as compared to placebo, no additional treatment or another protective medical intervention.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, MEDLINE (PubMed) and Embase (Ovid) to 8 January 2019. We handsearched reference lists of relevant articles and assessed the conference proceedings of the International Society for Paediatric Oncology (2006 up to and including 2018), the American Society of Pediatric Hematology/Oncology (2007 up to and including 2018) and the International Conference on Long-Term Complications of Treatment of Children and Adolescents for Cancer (2010 up to and including 2015). We scanned ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP; apps.who.int/trialsearch) for ongoing trials (on 2 January 2019).

SELECTION CRITERIA

Randomized controlled trials (RCTs) or controlled clinical trials (CCTs) evaluating platinum-based therapy with an otoprotective medical intervention versus platinum-based therapy with placebo, no additional treatment or another protective medical intervention in children with cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, data extraction, risk of bias assessment and GRADE assessment of included studies, including adverse effects. We performed analyses according to the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified two RCTs and one CCT (total number of participants 149) evaluating the use of amifostine versus no additional treatment in the original version of the review; the updates identified no additional studies. Two studies included children with osteosarcoma, and the other study included children with hepatoblastoma. Children received cisplatin only or a combination of cisplatin and carboplatin, either intra-arterially or intravenously. Pooling of results of the included studies was not possible. From individual studies the effect of amifostine on symptomatic ototoxicity only (i.e. National Cancer Institute Common Toxicity Criteria version 2 (NCICTCv2) or modified Brock grade 2 or higher) and combined asymptomatic and symptomatic ototoxicity (i.e. NCICTCv2 or modified Brock grade 1 or higher) were uncertain (low-certainty evidence). Only one study including children with osteosarcoma treated with intra-arterial cisplatin provided information on tumour response, defined as the number of participants with a good or partial remission. The available-data analysis (data were missing for one participant), best-case scenario analysis and worst-case scenario analysis showed a difference in favour of amifostine, although the certainty of evidence for this effect was low. There was no information on survival for any of the included studies. Only one study, including children with osteosarcoma treated with intra-arterial cisplatin, provided data on the number of participants with adverse effects other than ototoxicity grade 3 or higher (on NCICTCv2 scale). There was low-certainty evidence that grade 3 or 4 vomiting was higher with amifostine (risk ratio (RR) 9.04, 95% confidence interval (CI) 1.99 to 41.12). The effects on cardiotoxicity and renal toxicity grade 3 or 4 were uncertain (low-certainty evidence). None of the studies evaluated quality of life.In the recent update, we also identified one RCT including 109 children with localized hepatoblastoma evaluating the use of sodium thiosulfate versus no additional treatment. Children received intravenous cisplatin only (one child also received carboplatin). There was moderate-certainty evidence that both symptomatic ototoxicity only (i.e. Brock criteria grade 2 or higher) and combined asymptomatic and symptomatic ototoxicity (i.e. Brock criteria grade 1 or higher) was lower with sodium thiosulfate (combined asymptomatic and symptomatic ototoxicity: RR 0.52, 95% CI 0.33 to 0.81; symptomatic ototoxicity only: RR 0.39, 95% CI 0.19 to 0.83). The effect of sodium thiosulfate on tumour response (defined as number of participants with a complete or partial response at the end of treatment), overall survival (calculated from time of randomization to death or last follow-up), event-free survival (calculated from time of randomization until disease progression, disease relapse, second primary cancer, death, or last follow-up, whichever came first) and adverse effects other than hearing loss and tinnitus grade 3 or higher (according to National Cancer Institute Common Toxicity Criteria Adverse Effects version 3 (NCICTCAEv3) criteria) was uncertain (low-certainty evidence for all these outcomes). Quality of life was not assessed.We found no eligible studies for possible otoprotective medical interventions other than amifostine and sodium thiosulfate and for other types of malignancies.

AUTHORS' CONCLUSIONS

At the moment there is no evidence from individual studies in children with osteosarcoma or hepatoblastoma treated with different platinum analogues and dosage schedules that underscores the use of amifostine as an otoprotective intervention as compared to no additional treatment. Since pooling of results was not possible and the evidence was of low certainty, no definitive conclusions can be made. Since we found only one RCT evaluating the use of sodium thiosulfate in children with localized hepatoblastoma treated with cisplatin, no definitive conclusions on benefits and harms can be drawn. It should be noted that 'no evidence of effect', as identified in this review, is not the same as 'evidence of no effect'. We identified no eligible studies for other possible otoprotective medical interventions and other types of malignancies, so no conclusions can be made about their efficacy in preventing ototoxicity in children treated with platinum-based therapy. More high-quality research is needed.

Cochrane corner: platinum-induced hearing loss after treatment for childhood cancer

This Cochrane Corner features the review entitled "Platinum-induced hearing loss after treatment for childhood cancer" published in 2016. In their review, van As et al. identified 13 cohort studies including 2837 participants with a hearing test after treatment with a platinum-based therapy for different types of childhood cancers. All studies had problems related to quality of the evidence. The reported frequency of hearing loss varied between 1.7% and 90.1% for studies that included a definition of hearing loss; none of the studies provided data on tinnitus. Only two studies evaluated possible risk factors. One study found a higher risk of hearing loss in people treated with the combination of cisplatin plus carboplatin compared to treatment with cisplatin only and for exposure to aminoglycosides. The other found that age at treatment (lower risk in older children) and single maximum cisplatin dose (higher risk with an increasing dose) were significant predictors for hearing loss, while gender was not. This systematic review shows that children treated with platinum analogues are at risk of developing hearing loss, but the exact prevalence and risk factors remain unclear.

Prolonged furosemide exposure and risk of abnormal newborn hearing screen in premature infants

BACKGROUND

At very high doses, furosemide is linked to ototoxicity in adults, but little is known about the risk of hearing loss in premature infants exposed to furosemide.

AIMS

Evaluate the association between prolonged furosemide exposure and abnormal hearing screening in premature infants.

STUDY DESIGN

Using propensity scoring, infants with prolonged (≥28 days) exposure to furosemide were matched to infants never exposed. The matched sample was used to estimate the impact of prolonged furosemide exposure on the probability of an abnormal hearing screen prior to hospital discharge.

SUBJECTS

A cohort of infants 501-1250 g birth weight and 23-29 weeks gestational age discharged home from 210 neonatal intensive care units in the United States (2004-2013).

OUTCOME MEASURES

We defined abnormal hearing screen as a result of either "fail" or "refer" for either ear.

RESULTS

Altogether, 1020 infants exposed to furosemide for ≥28 days were matched to 790 unique infants never exposed, yielding a total of 1042 matches due to sampling with replacement and propensity score ties. Matching resulted in a population similar in baseline characteristics. After adjusting for covariates, the proportion of infants with an abnormal hearing screen in the furosemide-exposed group was not significantly higher than the never-exposed group (absolute difference 3.0% [95% CI -0.2-6.2%], P = 0.07).

CONCLUSIONS

Prolonged furosemide exposure was associated with a positive, but not statistically significant, difference in abnormal hearing screening in premature infants. Additional studies with post-hospital discharge audiology follow-up are needed to further evaluate the safety of furosemide in this population.

Different infusion durations for preventing platinum-induced hearing loss in children with cancer

BACKGROUND

Platinum-based therapy, including cisplatin, carboplatin or oxaliplatin, or a combination of these, is used to treat a variety of paediatric malignancies. Unfortunately, one of the most important adverse effects is the occurrence of hearing loss or ototoxicity. In an effort to prevent this ototoxicity, different platinum infusion durations have been studied. This review is the second update of a previously published Cochrane review.

OBJECTIVES

To assess the effects of different durations of platinum infusion to prevent hearing loss or tinnitus, or both, in children with cancer. Secondary objectives were to assess possible effects of these infusion durations on: a) anti-tumour efficacy of platinum-based therapy, b) adverse effects other than hearing loss or tinnitus, and c) quality of life.

SEARCH METHODS

We searched the electronic databases Cochrane Central Register of Controlled Trials (CENTRAL; the Cochrane Library 15 March 2018), MEDLINE (PubMed) (1945 to 15 March 2018) and Embase (Ovid) (1980 to 15 March 2018). In addition, we handsearched reference lists of relevant articles and we assessed the conference proceedings of the International Society for Paediatric Oncology (2009 up to and including 2017) and the American Society of Pediatric Hematology/Oncology (2014 up to and including 2017). We scanned ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP; apps.who.int/trialsearch) for ongoing trials (searched on 12 March 2018 and 13 March 2018 respectively).

SELECTION CRITERIA

Randomised controlled trials (RCTs) or controlled clinical trials (CCTs) comparing different platinum infusion durations in children with cancer. Only the platinum infusion duration could differ between the treatment groups.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, 'Risk of bias' assessment and GRADE assessment of included studies, and data extraction including adverse effects. Analyses were performed according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified one RCT and no CCTs; in this update no additional studies were identified. The RCT (total number of children = 91) evaluated the use of a continuous cisplatin infusion (N = 43) versus a one-hour bolus cisplatin infusion (N = 48) in children with neuroblastoma. For the continuous infusion, cisplatin was administered on days one to five of the cycle, but it is unclear if the infusion duration was a total of five days. Risk of bias was present. Only results from shortly after induction therapy were provided. No clear evidence of a difference in hearing loss (defined as asymptomatic and symptomatic disease combined) between the different infusion durations was identified as results were imprecise (risk ratio (RR) 1.39, 95% confidence interval (CI) 0.47 to 4.13, low-quality evidence). Although the numbers of children were not provided, it was stated that tumour response was equivalent in both treatment arms. With regard to adverse effects other than ototoxicity, we were only able to assess toxic deaths. Again, the confidence interval of the estimated effect was too wide to exclude differences between the treatment groups (RR 1.12, 95% CI 0.07 to 17.31, low-quality evidence). No data were available for the other outcomes of interest (i.e. tinnitus, overall survival, event-free survival and quality of life) or for other (combinations of) infusion durations or other platinum analogues.

AUTHORS' CONCLUSIONS

Since only one eligible RCT evaluating the use of a continuous cisplatin infusion versus a one-hour bolus cisplatin infusion was found, and that had methodological limitations, no definitive conclusions can be made. It should be noted that 'no evidence of effect', as identified in this review, is not the same as 'evidence of no effect'. For other (combinations of) infusion durations and other platinum analogues no eligible studies were identified. More high-quality research is needed.

Prospective Study of Gastroesophageal Reflux, Use of Proton Pump Inhibitors and H2-Receptor Antagonists, and Risk of Hearing Loss

OBJECTIVES

Gastroesophageal reflux disease (GERD) is common and often treated with proton pump inhibitors (PPIs) or H2-receptor antagonists (H2-RAs). GERD has been associated with exposure of the middle ear to gastric contents, which could cause hearing loss. Treatment of GERD with PPIs and H2-RAs may decrease exposure of the middle ear to gastric acid and decrease the risk of hearing loss. We prospectively investigated the relation between GERD, use of PPIs and H2-RAs, and the risk of hearing loss in 54,883 women in Nurses' Health Study II.

DESIGN

Eligible participants, aged 41 to 58 years in 2005, provided information on medication use and GERD symptoms in 2005, answered the question on hearing loss in 2009 or in 2013, and did not report hearing loss starting before the date of onset of GERD symptoms or medication use. The primary outcome was self-reported hearing loss. Cox proportional hazards regression was used to adjust for potential confounders.

RESULTS

During 361,872 person-years of follow-up, 9842 new cases of hearing loss were reported. Compared with no GERD symptoms, higher frequency of GERD symptoms was associated with higher risk of hearing loss (multivariable adjusted relative risks: <1 time/month 1.04 [0.97, 1.11], several times/week 1.17 [1.09, 1.25], daily 1.33 [1.19, 1.49]; p value for trend <0.001). After accounting for GERD symptoms, neither PPI nor H2-RA use was associated with the risk of hearing loss.

CONCLUSIONS

GERD symptoms are associated with higher risk of hearing loss in women, but use of PPIs and H2-RAs are not independently associated with the risk.

Determinants of ototoxicity in 451 platinum-treated Dutch survivors of childhood cancer: A DCOG late-effects study

Platinum-containing chemotherapeutics are efficacious for a variety of pediatric malignancies, nevertheless these drugs can induce ototoxicity. However, ototoxicity data on large cohorts of childhood cancer survivors (CCSs) who received platinum agents, but not cranial irradiation are scarce. Therefore, we have studied the frequency and determinants of ototoxicity in a cross-sectional multicenter CCS cohort, including the role of co-medication since it has been suggested that these play a role in ototoxicity. We have collected treatment data and audiograms from the medical records of CCS treated in the seven pediatric oncology centres in The Netherlands. Ototoxicity was defined as Münster grade ≥2b (>20 dB at ≥4-8 kHz). Four-hundred-fifty-one CCS who received platinum agents, but not cranial irradiation (median age at diagnosis: 4.9 years, range: 0.01-19 years) were included. The overall frequency of ototoxicity was 42%. Ototoxicity was observed in 45% of the cisplatin-treated CCS, in 17% of the carboplatin-treated CCS and in 75% of the CCS that had received both agents. Multivariate analysis showed that younger age at diagnosis (odds ratio [OR]: 0.6, 95% confidence interval [CI]: 0.5-0.6 per 5 years increase); higher total cumulative dose cisplatin (OR: 1.2, 95% CI: 1.2-1.5 per 100 mg/m² increase); and co-treatment with furosemide (OR: 2.3, 95% CI: 1.4-3.9) were associated with ototoxicity. We conclude that treatment with (higher total cumulative dose of) cisplatin, young age and furosemide co-medication independently are associated with an increased risk of ototoxicity in CCS. Future prospective studies are necessary to confirm the additive risk of co-medication on the development of ototoxicity.

Ototoxic effects and mechanisms of loop diuretics

Over the past two decades considerable progress has been made in understanding the ototoxic effects and mechanisms underlying loop diuretics. As typical representative of loop diuretics ethacrynic acid or furosemide only induces temporary hearing loss, but rarely permanent deafness unless applied in severe acute or chronic renal failure or with other ototoxic drugs. Loop diuretic induce unique pathological changes in the cochlea such as formation of edematous spaces in the epithelium of the stria vascularis, which leads to rapid decrease of the endolymphatic potential and eventual loss of the cochlear microphonic potential, summating potential, and compound action potential. Loop diuretics interfere with strial adenylate cyclase and Na+/K+-ATPase and inhibit the Na-K-2Cl cotransporter in the stria vascularis, however recent reports indicate that one of the earliest effects in vivo is to abolish blood flow in the vessels supplying the lateral wall. Since ethacrynic acid does not damage the stria vascularis in vitro, the changes in Na+/K+-ATPase and Na-K-2Cl seen in vivo may be secondary effects results from strial ischemia and anoxia. Recent observations showing that renin is present in pericytes surrounding stria arterioles suggest that diuretics may induce local vasoconstriction by renin secretion and angiotensin formation. The tight junctions in the blood-cochlea barrier prevent toxic molecules and pathogens from entering cochlea, but when diuretics induce a transient ischemia, the barrier is temporarily disrupted allowing the entry of toxic chemicals or pathogens.

Medical interventions for the prevention of platinum-induced hearing loss in children with cancer

BACKGROUND

Platinum-based therapy, including cisplatin, carboplatin, oxaliplatin or a combination of these, is used to treat a variety of paediatric malignancies. One of the most important adverse effects is the occurrence of hearing loss or ototoxicity. In an effort to prevent this ototoxicity, different otoprotective medical interventions have been studied. This review is the second update of a previously published Cochrane review.

OBJECTIVES

To assess the efficacy of medical interventions to prevent hearing loss and to determine possible effects of these interventions on anti-tumour efficacy, toxicities other than hearing loss and quality of life in children with cancer treated with platinum-based therapy.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 6), MEDLINE (PubMed) (1945 to 8 July 2016) and EMBASE (Ovid) (1980 to 8 July 2016). In addition, we handsearched reference lists of relevant articles and we assessed the conference proceedings of the International Society for Paediatric Oncology (2006 up to and including 2015), the American Society of Pediatric Hematology/Oncology (2007 up to and including 2016) and the International Conference on Long-Term Complications of Treatment of Children and Adolescents for Cancer (2010 up to and including 2015). We scanned the International Standard Randomized Controlled Trial Number (ISRCTN) Register (www.isrctn.com) and the National Institute of Health Register (www.clinicaltrials.gov) for ongoing trials (both searched on 12 July 2016).

SELECTION CRITERIA

Randomized controlled trials (RCTs) or controlled clinical trials (CCTs) evaluating platinum-based therapy together with an otoprotective medical intervention versus platinum-based therapy with placebo, no additional treatment or another protective medical intervention in children with cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, data extraction, risk of bias assessment and GRADE assessment of included studies, including adverse effects. We performed analyses according to the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified two RCTs and one CCT (total number of participants 149) evaluating the use of amifostine versus no additional treatment in the original version of the review; the updates identified no additional studies. Two studies included children with osteosarcoma, and the other study included children with hepatoblastoma. Children received cisplatin only or a combination of cisplatin and carboplatin, either intra-arterially or intravenously. Pooling of results of the included studies was not possible. However, in the individual studies there was no significant difference in symptomatic ototoxicity only (that is, grade 2 or higher) and combined asymptomatic and symptomatic ototoxicity (that is, grade 1 or higher) between children treated with or without amifostine. Only one study, including children with osteosarcoma treated with intra-arterial cisplatin, provided information on tumour response, defined as the number of participants with a good or partial remission. The available data analysis (data were missing for one participant), best case scenario analysis and worst case scenario analysis all showed a difference in favour of amifostine, but this difference was significant only in the worst case scenario analysis (P = 0.04). There was no information on survival for any of the included studies. Only one study, including children with osteosarcoma treated with intra-arterial cisplatin, provided data on the number of participants with adverse effects other than ototoxicity grade 3 or higher. There was a significant difference in favour of the control group in the occurrence of vomiting grade 3 or 4 (risk ratio (RR) 9.04; 95% confidence interval (CI) 1.99 to 41.12; P = 0.004). There was no significant difference between treatment groups for cardiotoxicity and renal toxicity grade 3 or 4. None of the studies evaluated quality of life. The quality of evidence for the different outcomes was low. We found no eligible studies for possible otoprotective medical interventions other than amifostine and other types of malignancies.

AUTHORS' CONCLUSIONS

At the moment there is no evidence from individual studies in children with osteosarcoma or hepatoblastoma treated with different platinum analogues and dosage schedules that underscores the use of amifostine as an otoprotective intervention as compared to no additional treatment. Since pooling of results was not possible and all studies had serious methodological limitations, no definitive conclusions can be made. It should be noted that 'no evidence of effect', as identified in this review, is not the same as 'evidence of no effect'. Based on the currently available evidence, we are unable to give recommendations for clinical practice. We identified no eligible studies for other possible otoprotective medical interventions and other types of malignancies, so no conclusions can be made about their efficacy in preventing ototoxicity in children treated with platinum-based therapy. More high quality research is needed.

Loop Diuretics in the Treatment of Hypertension

Loop diuretics are not recommended in current hypertension guidelines largely due to the lack of outcome data. Nevertheless, they have been shown to lower blood pressure and to offer potential advantages over thiazide-type diuretics. Torsemide offers advantages of longer duration of action and once daily dosing (vs. furosemide and bumetanide) and more reliable bioavailability (vs. furosemide). Studies show that the previously employed high doses of thiazide-type diuretics lower BP more than furosemide. Loop diuretics appear to have a preferable side effect profile (less hyponatremia, hypokalemia, and possibly less glucose intolerance). Studies comparing efficacy and side effect profiles of loop diuretics with the lower, currently widely prescribed, thiazide doses are needed. Research is needed to fill gaps in knowledge and common misconceptions about loop diuretic use in hypertension and to determine their rightful place in the antihypertensive arsenal.

Different infusion durations for preventing platinum-induced hearing loss in children with cancer

BACKGROUND

Platinum-based therapy, including cisplatin, carboplatin or oxaliplatin, or a combination of these, is used to treat a variety of paediatric malignancies. Unfortunately, one of the most important adverse effects is the occurrence of hearing loss or ototoxicity. In an effort to prevent this ototoxicity, different platinum infusion durations have been studied. This review is an update of a previously published Cochrane review.

OBJECTIVES

To assess the effects of different durations of platinum infusion to prevent hearing loss or tinnitus, or both, in children with cancer. Secondary objectives were to assess possible effects of these infusion durations on: a) anti-tumour efficacy of platinum-based therapy, b) adverse effects other than hearing loss or tinnitus, and c) quality of life.

SEARCH METHODS

We searched the electronic databases Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2016, Issue 4), MEDLINE (PubMed) (1945 to 18 May 2016) and EMBASE (Ovid) (1980 to 18 May 2016). In addition, we handsearched reference lists of relevant articles and we assessed the conference proceedings of the International Society for Paediatric Oncology (2009 up to and including 2015) and the American Society of Pediatric Hematology/Oncology (2014 and 2015). We scanned ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP; apps.who.int/trialsearch) for ongoing trials (searched on 20 May 2016 and 24 May 2016 respectively).

SELECTION CRITERIA

Randomised controlled trials (RCTs) or controlled clinical trials (CCTs) comparing different platinum infusion durations in children with cancer. Only the platinum infusion duration could differ between the treatment groups.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, risk of bias assessment and GRADE assessment of included studies, and data extraction including adverse effects. Analyses were performed according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified one RCT and no CCTs; in this update no additional studies were identified. The RCT (total number of children = 91) evaluated the use of a continuous cisplatin infusion (N = 43) versus a one-hour bolus cisplatin infusion (N = 48) in children with neuroblastoma. For the continuous infusion, cisplatin was administered on days 1 to 5 of the cycle but it is unclear if the infusion duration was a total of 5 days. Methodological limitations were present. Only results from shortly after induction therapy were provided. No clear evidence of a difference in hearing loss (defined as asymptomatic and symptomatic disease combined) between the different infusion durations was identified as results were imprecise (risk ratio (RR) 1.39, 95% confidence interval (CI) 0.47 to 4.13, low quality evidence). Although the numbers of children were not provided, it was stated that tumour response was equivalent in both treatment arms. With regard to adverse effects other than ototoxicity we were only able to assess toxic deaths. Again, the confidence interval of the estimated effect was too wide to exclude differences between the treatment groups (RR 1.12, 95% CI 0.07 to 17.31, low quality evidence). No data were available for the other outcomes of interest (i.e. tinnitus, overall survival, event-free survival and quality of life) or for other (combinations of) infusion durations or other platinum analogues.

AUTHORS' CONCLUSIONS

Since only one eligible RCT evaluating the use of a continuous cisplatin infusion versus a one-hour bolus cisplatin infusion was found, and that had methodological limitations, no definitive conclusions can be made. It should be noted that 'no evidence of effect', as identified in this review, is not the same as 'evidence of no effect'. For other (combinations of) infusion durations and other platinum analogues no eligible studies were identified. More high quality research is needed.

Platinum-induced hearing loss after treatment for childhood cancer

BACKGROUND

Platinum-based therapy, including cisplatin, carboplatin, oxaliplatin or a combination of these, is used to treat a variety of paediatric malignancies. Unfortunately, one of the most important adverse effects is the occurrence of hearing loss or ototoxicity. There is a wide variation in the reported prevalence of platinum-induced ototoxicity and the associated risk factors. More insight into the prevalence of and risk factors for platinum-induced hearing loss is essential in order to develop less ototoxic treatment protocols for the future treatment of children with cancer and to develop adequate follow-up protocols for childhood cancer survivors treated with platinum-based therapy.

OBJECTIVES

To evaluate the existing evidence on the association between childhood cancer treatment including platinum analogues and the occurrence of hearing loss.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2015, Issue 8), MEDLINE (PubMed) (1945 to 23 September 2015) and EMBASE (Ovid) (1980 to 23 September 2015). In addition, we searched reference lists of relevant articles and the conference proceedings of the International Society for Paediatric Oncology (2008 to 2014), the American Society of Pediatric Hematology/Oncology (2008 to 2015) and the International Conference on Long-Term Complications of Treatment of Children and Adolescents for Cancer (2010 to 2015). Experts in the field provided information on additional studies.

SELECTION CRITERIA

All study designs, except case reports, case series (i.e. a description of non-consecutive participants) and studies including fewer than 100 participants treated with platinum-based therapy who had an ototoxicity assessment, examining the association between childhood cancer treatment including platinum analogues and the occurrence of hearing loss.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection. One review author performed data extraction and risk of bias assessment, which was checked by another review author.

MAIN RESULTS

We identified 13 eligible cohort studies including 2837 participants with a hearing test after treatment with a platinum analogue for different types of childhood cancers. All studies had methodological limitations, with regard to both internal (risk of bias) and external validity. Participants were treated with cisplatin, carboplatin or both, in varying doses. The reported prevalence of hearing loss varied considerably between 0% and 90.1%; none of the studies provided data on tinnitus. Three studies reported a prevalence of 0%, but none of these studies provided a definition for hearing loss and there might be substantial or even complete overlap in included participants between these three studies. When only studies that did provide a definition for hearing loss were included, the prevalence of hearing loss still varied widely between 1.7% and 90.1%. All studies were very heterogeneous with regard to, for example, definitions of hearing loss, used diagnostic tests, participant characteristics, (prior) anti-tumour treatment, other ototoxic drugs and length of follow-up. Therefore, pooling of results was not possible.Only two studies included a control group of people who had not received platinum treatment. In one study, the prevalence of hearing loss was 67.1% (95% confidence interval (CI) 59.3% to 74.1%) in platinum-treated participants, while in the control participants it was 7.4% (95% CI 6.2% to 8.8%). However, hearing loss was detected by screening in survivors treated with platinum analogues and by clinical presentation in control participants. It is uncertain what the effect of this difference in follow-up/diagnostic testing was. In the other study, the prevalence of hearing loss was 20.1% (95% CI 17.4% to 23.2%) in platinum-treated participants and 0.4% (95% CI 0.12% to 1.6%) in control participants. As neither study was a randomized controlled trial or controlled clinical trial, the calculation of a risk ratio was not feasible as it is very likely that both groups differed more than only the platinum treatment.Only two studies evaluated possible risk factors using multivariable analysis. One study identified a significantly higher risk of hearing loss in people treated with cisplatin 400 mg/m(2) plus carboplatin 1700 mg/m(2) as compared to treatment with cisplatin 400 mg/m(2) or less, irrespective of the definition of hearing loss. They also identified a significantly higher risk of hearing loss in people treated with non-anthracycline aminoglycosides antibiotics (using a surrogate marker) as compared to people not treated with them, for three out of four definitions of hearing loss. The other study reported that age at treatment (odds ratio less than 1 for each single-unit increase) and single maximum cisplatin dose (odds ratio greater than 1 for each single-unit increase) were significant predictors for hearing loss, while gender was not.

AUTHORS' CONCLUSIONS

This systematic review shows that children treated with platinum analogues are at risk for developing hearing loss, but the exact prevalence and risk factors remain unclear. There were no data available for tinnitus. Based on the currently available evidence we can only advise that children treated with platinum analogues are screened for ototoxicity in order to make it possible to diagnose hearing loss early and to take appropriate measures. However, we are unable to give recommendations for specific follow-up protocols including frequency of testing. Counselling regarding the prevention of noise pollution can be considered, such as the use of noise-limiting equipment, avoiding careers with excess noise and ototoxic medication. Before definitive conclusions on the prevalence and associated risk factors of platinum-induced ototoxicity can be made, more high-quality research is needed. Accurate and transparent reporting of findings will make it possible for readers to appraise the results of these studies critically.

Hypertension, Diuretic Use, and Risk of Hearing Loss

BACKGROUND

Hearing loss is highly prevalent among adults in the United States. Hypertension also is common and often treated with diuretics. Hypertension may increase the risk of hearing loss by decreasing vascular supply to the stria vascularis. Use of thiazides has been anecdotally associated with hearing loss. In small studies, furosemide use has been associated with hearing loss that is usually reversible, but can be permanent. We investigated the relation among hypertension, diuretic use, and hearing loss in a prospective cohort of 54,721 women in the Nurses' Health Study I, 1994 to 2012.

METHODS

Eligible participants included 54,721 female nurses aged 48 to 73 years in 1994 who provided information on thiazide diuretic and furosemide use in 1994, answered the question on hearing loss over their lifetime in 2012, and did not report hearing loss with date of onset before date of onset of hypertension diagnosis or medication use. The outcome was self-reported hearing loss. Cox proportional hazards regression was used to adjust for potential confounders.

RESULTS

During 774,096 person-years of follow-up, 19,296 cases of hearing loss were reported (incidence rate, 25 cases per 1000 person-years). At baseline in 1994, the mean age was 57.9 years and mean body mass index was 26.3 kg/m(2). Some 30.8% of participants had a history of hypertension. History of hypertension was independently associated with a modestly higher risk of hearing loss (multivariable adjusted relative risk, 1.04 [1.01-1.07]). Among women with a history of hypertension, neither thiazide diuretic (multivariable adjusted relative risk, 1.07 [0.99-1.16]) nor furosemide use (multivariable adjusted relative risk, 0.91 [0.75-1.09]) was significantly associated with risk of hearing loss when compared with women not taking antihypertensive medications. There was no significant effect modification by age.

CONCLUSIONS

History of hypertension was associated with a small increased risk of hearing loss. Thiazide diuretic use and furosemide use were not associated with risk of hearing loss among women with a history of hypertension.

Medical interventions for the prevention of platinum-induced hearing loss in children with cancer

BACKGROUND

Platinum-based therapy, including cisplatin, carboplatin and/or oxaliplatin, is used to treat a variety of paediatric malignancies. Unfortunately, one of the most important adverse effects is the occurrence of hearing loss or ototoxicity. In an effort to prevent this ototoxicity, different otoprotective medical interventions have been studied. This review is an update of a previously published Cochrane review.

OBJECTIVES

The primary objective was to assess the efficacy of any medical intervention to prevent hearing loss in children with cancer treated with platinum-based therapy (that is including cisplatin, carboplatin and/or oxaliplatin) when compared to placebo, no additional treatment or a different protective medical intervention. Secondary objectives were to determine possible effects of these interventions on anti-tumour efficacy, toxicities other than hearing loss and quality of life.

SEARCH METHODS

We searched the electronic databases Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 1), MEDLINE (PubMed) (1945 to 17 March 2014) and EMBASE (Ovid) (1980 to 17 March 2014). In addition, we handsearched reference lists of relevant articles and the conference proceedings of the International Society for Paediatric Oncology (2006 to 2013), the American Society of Pediatric Hematology/Oncology (2007 to 2013) and the International Conference on Long-Term Complications of Treatment of Children and Adolescents for Cancer (2010 to 2013). We scanned the International Standard Randomized Controlled Trial Number (ISRCTN) Register and the National Institute of Health Register for ongoing trials (www.controlled-trials.com) (searched on 17 March 2014).

SELECTION CRITERIA

Randomized controlled trials (RCTs) or controlled clinical trials (CCTs) evaluating platinum-based therapy together with an otoprotective medical intervention versus platinum-based therapy with placebo, no additional treatment or another protective medical intervention in children with cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, risk of bias assessment of included studies and data extraction, including adverse effects. Analyses were performed according to the guidelines in the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified two RCTs and one CCT (total number of patients 149) evaluating the use of amifostine versus no additional treatment in the original version of the review; in this update no additional studies were identified. Two studies included children with osteosarcoma, and the other study included children with hepatoblastoma. Patients received cisplatin only or a combination of cisplatin and carboplatin, either administered intra-arterially or intravenously. All studies had methodological limitations. Unfortunately pooling of the results of the included studies was not possible. However, in the individual studies no significant difference was identified in symptomatic ototoxicity only (that is grade 2 or higher) and combined asymptomatic and symptomatic ototoxicity (that is grade 1 or higher) between children treated with or without amifostine. Only one study, including children with osteosarcoma treated with intra-arterial cisplatin, provided information on tumour response, defined as the number of patients with a good or partial remission. The available data analysis (data were missing for one patient), best case scenario analysis and worst case scenario analysis all showed a difference in favour of amifostine, but this difference was significant only in the worst case scenario analysis (P = 0.04). No information on survival was available for any of the included study populations. Only one study, including children with osteosarcoma treated with intra-arterial cisplatin, provided data on the number of patients with adverse effects other than ototoxicity grade 3 or higher. There was a significant difference in favour of the control group in the occurrence of vomiting grade 3 or 4 (risk ratio (RR) 9.04; 95% confidence interval (CI) 1.99 to 41.12; P = 0.004). No significant difference was identified between treatment groups for cardiotoxicity and renal toxicity grade 3 or 4. None of the studies evaluated quality of life. No eligible studies were found for possible otoprotective medical interventions other than amifostine and other types of malignancies.

AUTHORS' CONCLUSIONS

At the moment there is no evidence from individual studies in children with osteosarcoma or hepatoblastoma treated with different platinum analogues and dosage schedules which underscores the use of amifostine as an otoprotective intervention as compared to no additional treatment. Since pooling of results was not possible and all studies had serious methodological limitations, no definitive conclusions can be made. It should be noted that 'no evidence of effect', as identified in this review, is not the same as 'evidence of no effect'. Based on the currently available evidence, we are not able to give recommendations for clinical practice. No eligible studies were identified for other possible otoprotective medical interventions and other types of malignancies, so no conclusions can be made about their efficacy in preventing ototoxicity in children treated with platinum-based therapy. More high quality research is needed.

Different infusion durations for preventing platinum-induced hearing loss in children with cancer

BACKGROUND

Platinum-based therapy, including cisplatin, carboplatin or oxaliplatin, or a combination of these, is used to treat a variety of paediatric malignancies. Unfortunately, one of the most important adverse effects is the occurrence of hearing loss or ototoxicity. In an effort to prevent this ototoxicity, different platinum infusion durations have been studied.

OBJECTIVES

To assess the effects of different durations of platinum infusion to prevent hearing loss or tinnitus, or both, in children with cancer. Secondary objectives were to assess possible effects of these infusion durations on: a) anti-tumour efficacy of platinum-based therapy, b) adverse effects other than hearing loss or tinnitus, and c) quality of life.

SEARCH METHODS

We searched the electronic databases Cochrane Central Register of Controlled Trials (CENTRAL 2013, Issue 12), MEDLINE (PubMed) (1945 to 4 December 2013) and EMBASE (Ovid) (1980 to 4 December 2013). In addition, we handsearched reference lists of relevant articles and the conference proceedings of the International Society for Paediatric Oncology (2009 to 2013). We scanned ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) (http://www.who.int/ictrp/en/) for ongoing trials (both searched on 13 December 2013).

SELECTION CRITERIA

Randomised controlled trials (RCTs) or controlled clinical trials (CCTs) comparing different platinum infusion durations in children with cancer. Only the platinum infusion duration could differ between the treatment groups.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, risk of bias assessment and GRADE assessment of included studies, and data extraction including adverse effects. Analyses were performed according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified one RCT and no CCTs. The RCT (total number of children = 91) evaluated the use of a continuous cisplatin infusion (N = 43) versus a one hour bolus cisplatin infusion (N = 48) in children with neuroblastoma. For the continuous infusion, cisplatin was administered on days 1 to 5 of the cycle but it is unclear if the infusion duration was a total of 5 days. Methodological limitations were present. Only results from shortly after induction therapy were provided. No clear evidence of a difference in hearing loss (defined as asymptomatic and symptomatic disease combined) between the different infusion durations was identified as results were imprecise (RR 1.39; 95% CI 0.47 to 4.13, low quality evidence). Although the numbers of children were not provided, it was stated that tumour response was equivalent in both treatment arms. With regard to adverse effects other than ototoxicity we were only able to assess toxic deaths. Again, the confidence interval of the estimated effect was too wide to exclude differences between the treatment groups (RR 1.12; 95% CI 0.07 to 17.31, low quality evidence). No data were available for the other outcomes of interest (i.e. tinnitus, overall survival, event-free survival and quality of life) or for other (combinations of) infusion durations or other platinum analogues.

AUTHORS' CONCLUSIONS

Since only one eligible RCT evaluating the use of a continuous cisplatin infusion versus a one hour bolus cisplatin infusion was found, and that had methodological limitations, no definitive conclusions can be made. It should be noted that 'no evidence of effect', as identified in this review, is not the same as 'evidence of no effect'. For other (combinations of) infusion durations and other platinum analogues no eligible studies were identified. More high quality research is needed.

Clinical pharmacology of furosemide in neonates: a review

Furosemide is the diuretic most used in newborn infants. It blocks the Na⁺-K⁺-2Cl⁻ symporter in the thick ascending limb of the loop of Henle increasing urinary excretion of Na⁺ and Cl⁻. This article aimed to review the published data on the clinical pharmacology of furosemide in neonates to provide a critical, comprehensive, authoritative and, updated survey on the metabolism, pharmacokinetics, pharmacodynamics and side-effects of furosemide in neonates. The bibliographic search was performed using PubMed and EMBASE databases as search engines; January 2013 was the cutoff point. Furosemide half-life (t_1/2) is 6 to 20-fold longer, clearance (Cl) is 1.2 to 14-fold smaller and volume of distribution (Vd) is 1.3 to 6-fold larger than the adult values. t_1/2 shortens and Cl increases as the neonatal maturation proceeds. Continuous intravenous infusion of furosemide yields more controlled diuresis than the intermittent intravenous infusion. Furosemide may be administered by inhalation to infants with chronic lung disease to improve pulmonary mechanics. Furosemide stimulates prostaglandin E2 synthesis, a potent dilator of the patent ductus arteriosus, and the administration of furosemide to any preterm infants should be carefully weighed against the risk of precipitation of a symptomatic patent ductus arteriosus. Infants with low birthweight treated with chronic furosemide are at risk for the development of intra-renal calcifications.

Medical interventions for the prevention of platinum-induced hearing loss in children with cancer

BACKGROUND

Platinum-based therapy, including cisplatin, carboplatin and/or oxaliplatin, is used to treat a variety of paediatric malignancies. Unfortunately, one of the most important adverse effects is the occurrence of hearing loss or ototoxicity. In an effort to prevent this ototoxicity, different otoprotective medical interventions have been studied.

OBJECTIVES

The primary objective was to assess the efficacy of different otoprotective medical interventions in preventing hearing loss in children with cancer treated with platinum-based therapy. Secondary objectives were to determine possible effects of these interventions on anti-tumour efficacy, toxicities other than hearing loss and quality of life.

SEARCH METHODS

We searched the electronic databases Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 4), MEDLINE (PubMed) (1945 to 22 December 2011) and EMBASE (Ovid) (1980 to 22 December 2011). In addition, we handsearched reference lists of relevant articles and the conference proceedings of the International Society for Paediatric Oncology (2006 to 2011), the American Society of Pediatric Hematology/Oncology (2007 to 2011) and the International Conference on Long-Term Complications of Treatment of Children and Adolescents for Cancer (2010). We scanned the International Standard Randomized Controlled Trial Number (ISRCTN) Register and the National Institute of Health Register for ongoing trials (www.controlled-trials.com) (searched on 20 December 2011).

SELECTION CRITERIA

Randomized controlled trials (RCTs) or controlled clinical trials (CCTs) evaluating platinum-based therapy together with an otoprotective medical intervention versus platinum-based therapy with placebo, no additional treatment or another protective medical intervention in children with cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, risk of bias assessment of included studies and data extraction, including adverse effects. Analyses were performed according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified two RCTs and one CCT (total number of patients 149) evaluating the use of amifostine versus no additional treatment. Two studies included children with osteosarcoma, the other study included children with hepatoblastoma. Patients received cisplatin only or a combination of cisplatin and carboplatin, either administered intra-arterially or intravenously. All studies had methodological limitations. Unfortunately, pooling of the results of included studies was not possible. However, in all individual studies no significant difference was identified in symptomatic ototoxicity only (that is grade 2 or higher) and combined asymptomatic and symptomatic ototoxicity (that is grade 1 or higher) between children treated with or without amifostine. Only one study, including children with osteosarcoma treated with intra-arterial cisplatin, provided information on tumour response, defined as the number of patients with a good or partial remission. The 'available data' analysis (data were missing for one patient), 'best case scenario' analysis and 'worst case scenario' analysis all showed a difference in favour of amifostine, but this difference was significant only in the 'worst case scenario' analysis (P = 0.04). No information on survival was available for any of the included study populations. Only one study, including children with osteosarcoma treated with intra-arterial cisplatin, provided data on the number of patients with adverse effects other than ototoxicity grade 3 or higher. There was a significant difference in favour of the control group in the occurrence of vomiting grade 3 or 4 (RR 9.04; 95% CI 1.99 to 41.12; P = 0.004). No significant difference was identified between treatment groups for cardiotoxicity and renal toxicity grade 3 or 4. None of the studies evaluated quality of life. No eligible studies were found for possible otoprotective medical interventions other than amifostine and other types of malignancies.

AUTHORS' CONCLUSIONS

At the moment there is no evidence from individual studies in children with osteosarcoma and hepatoblastoma treated with different platinum analogues and dosage schedules which underscores the use of amifostine as an otoprotective intervention as compared to no additional treatment. Since pooling of results was not possible and all studies had serious methodological limitations, no definitive conclusions can be made. It should be noted that 'no evidence of effect', as identified in this review, is not the same as 'evidence of no effect'. Based on the currently available evidence, we are not able to give recommendations for clinical practice. For other possible otoprotective medical interventions and other types of malignancies no eligible studies were identified, so no conclusions can be made about their efficacy in preventing ototoxicity in children treated with platinum-based therapy. More high quality research is needed.

Nitroprusside in decompensated heart failure: what should a clinician really know?

Sodium nitroprusside is an older intravenous vasodilator appropriate for acute hospital treatment of patients with congestive heart failure. It is a balanced arterial and venous vasodilator with a very short half-life, facilitating rapid titration. In general, it improves hemodynamic and clinical status by reducing systemic vascular resistance, left ventricular filling pressure, and increasing cardiac output. This review summarizes recently published literature and recent data regarding the use of this intravenous vasodilator in decompensated heart failure patients.

A probable case of gabapentin-related reversible hearing loss in a patient with acute renal failure

BACKGROUND

As described in the literature, gabapentin toxicity in patients with impaired renal function can manifest as coma, myoclonus, tremulousness, or altered mental status. Gabapentin is an antiepileptic agent indicated for use as an adjunct therapy in partial seizures and postherpetic neuralgia but is also prescribed for the treatment of diabetic peripheral neuropathy.

CASE SUMMARY

A 46-year-old white woman (height, 167 cm; weight, 177 kg; body mass index, 62.8 kg/m2) with a 6-year history of diabetes mellitus and previously normal renal function, presented to the emergency department of Wake Forest University Baptist Medical Center with anuria (a serum creatinine level of 7.4 mg/dL), hearing loss, myoclonus, and confusion with hallucinations lasting for 3 days. Her blood pressure was 110/74 mm Hg. The patient's preadmit medication list included: lisinopril (40 mg QD), hydrochlorothiazide (25 mg QD), and furosemide (80 mg QD) for hypertension; atorvastatin (10 mg QD) for hyperlipidemia; omeprazole (20 mg QD) for gastroesophageal reflux disease; salmeterol/fluticasone inhaler (100/50 microg; 1 puff BID) and albuterol metered-dose inhaler (90 microg as needed) for asthma; metformin (500 mg BID) and insulin lispro per sliding scale for type 2 diabetes mellitus; oxycodone controlled release (60 mg TID) for chronic osteoarthritis and low back pain; alprazolam (0.5 mg every 8 hours as needed) for generalized anxiety disorder; venlafaxine (150 mg BID) for depression; and gabapentin (300 mg TID) for diabetic peripheral neuropathy. The patient's symptoms (hearing loss, myoclonus, and confusion) improved after 1 session of hemodialysis (approximately 10 hours following admission) and had resolved at the time of discharge (4 days later). On admission, the gabapentin concentration was 17.6 microg/mL, and following hemodialysis, the gabapentin concentration was undetectable (by discharge/day 4). The timing of the patient's last dose of gabapentin is unknown. Normal doses for the treatment of diabetic peripheral neuropathy range from 900 to 3600 mg/d divided 3 times daily.

CONCLUSIONS

We report a patient with acute renal failure who developed hearing loss, myoclonus, and confusion with hallucinations in the presence of elevated gabapentin concentrations. Due to rapid improvement after hemodialysis and discontinuation of gabapentin, we believe that these symptoms were probably due to gabapentin toxicity.

Loop diuretics: from the Na-K-2Cl transporter to clinical use

The diuretic response to loop diuretics in various disease states has consistently been found to be subnormal. One of the key determinants of the degree of diuretic response is the functional integrity of the sodium-potassium-chloride transporter in the loop of Henle. Studies in animal models suggest that expression/activity of the transporter may be affected by factors such as altered natural splicing events of NKCC2 (the gene encoding for the renal transporter), renal prostanoids, vasopressin, and other autacoids. We have reviewed the pharmacokinetics and pharmacodynamics of loop diuretics in health and in edematous disorders for which they are used. On the basis of evidence reviewed in this paper, we propose that altered expression or activity of the sodium-potassium-chloride transporter in the loop of Henle, in conjunction with events occurring in other segments of the nephron, possibly accounts for the altered diuretic response to these agents. Thus the modulators of this altered expression/activity could serve as important therapeutic targets for alternative diuretic regimens in these conditions.

Strategies for Treatment and Prevention of Acute Renal Failure

Acute renal failure (ARF) is a potentially life-threatening medical condition that often complicates the hospitalization of critically ill patients. A variety of therapeutic strategies has been studied for both preventing ischemic and nephrotoxic injury to the kidney and improving renal function in established ARF. This article summarizes the role of pharmacologic therapy in the treatment of ARF. Strategies to reduce extracellular fluid volume and preserve renal function with loop diuretics, low-dose dopamine, and renal replacement therapy will be discussed. The value of preventative therapy has increased, and identifying patients at high risk for development of ARF is critical. Modification of drug regimens, administration of less nephrotoxic medications, and volume expansion prior to nephrotoxin administration can minimize toxicity to the kidney. The search for new agents that can improve survival, decrease the need for renal replacement therapy, and hasten the recovery of renal function in ARF is ongoing.

Ototoxicity induced by gentamicin and furosemide

OBJECTIVE

To present a case of ototoxicity induced by furosemide and once-daily gentamicin therapy.

CASE SUMMARY

A 60-year-old white woman presented to the hospital with community-acquired pneumonia and urinary tract infection. The antibiotic regimen included gentamicin and, after 5 doses, the patient reported profound bilateral hearing loss. A Pure Tone Audiogram suggested moderate to moderately severe sensorineural hearing loss bilaterally. The only risk factors present included her age, elevated temperature, and the use of furosemide.

DISCUSSION

Several risk factors may predispose a patient to developing aminoglycoside ototoxicity: the 1555 chromosomal mutation, preexisting disorders of hearing and balance, hypovolemia, bacteremia, liver and renal dysfunction, and the simultaneous administration of other ototoxic medications. The cumulative dose and duration of aminoglycoside therapy are more important than serum concentrations. Administration of an aminoglycoside followed by furosemide may increase the risk of ototoxicity. The aminoglycoside interacts with the cell membranes in the inner ear, increasing their permeability. This theoretically allows the loop diuretic to penetrate into the cells in higher concentrations, causing more severe damage.

CONCLUSIONS

Auditory toxicity occurred after only 5 days of gentamicin therapy and 1 dose of furosemide. An aminoglycoside followed by furosemide may increase the risk for ototoxicity. Clinicians need to be aware of the synergistic potential of ototoxic medications.

Effect of posture on sodium excretion and diuretic efficacy in nephrotic patients

It is well known that posture affects natriuresis in cirrhosis and heart failure. This study evaluates the role of posture on spontaneous urinary salt excretion (U(Na)V) and diuretic-induced natriuresis in nephrotic patients with mild renal impairment. U(Na)V and plasma concentrations of the main hormones involved in sodium regulation were evaluated at baseline (Baseline) and after furosemide administration (20 mg intravenously at 8:00 AM [Diuretic]) in seven nephrotic patients with mild renal impairment (creatinine clearance, 68.5 +/- 7.6 mL/min) in either the supine or upright position for 6 hours (from 8:00 AM to 2:00 PM). At baseline, U(Na)V was greater in the supine than upright position (sodium, 51.8 +/- 6.2 versus 38.3 +/- 6.1 mEq/d; P: < 0.01). Similarly, furosemide was more effective in increasing U(Na)V in the supine (sodium, 51.8 +/- 6.2 to 87.4 +/- 9.1 mEq/d; P: < 0.005) than upright position (sodium, 38.3 +/- 6.1 to 59.0 +/- 6.8 mEq/d; P: = not significant). Consequently, body weight decreased in the supine but not the upright position (-0.73 +/- 0.15 versus -0.17 +/- 0.22 kg; P: < 0. 05). Peripheral renin activity (PRA) and plasma aldosterone (Aldo) concentrations were greater in the upright than supine position at both Baseline and Diuretic. A similar pattern was observed for hematocrit, used as an index of plasma volume. In addition, a positive correlation was detected between hematocrit and PRA (r = 0.89; P: < 0.001) in the upright position. Postural changes did not influence plasma concentrations of atrial natriuretic peptide. These data indicate that in nephrotic patients with mild impairment of glomerular filtration rate, the upright position causes a reduction in plasma volume; this hypovolemia activates the renin-Aldo system responsible for sodium retention in unstimulated conditions and a blunted natriuretic response to furosemide.

Treatment of edematous disorders with diuretics

Generalized edema results from alterations in renal sodium homeostasis that ultimately result in an expansion of extracellular fluid volume and accumulation of interstitial fluid. The common edematous disorders include congestive heart failure, cirrhosis, nephrotic syndrome, and renal insufficiency. The abnormalities of sodium homeostasis contributing to edema formation in each condition are discussed. Management of volume homeostasis, with an emphasis on the role of diuretic therapy, is reviewed.

Pharmacoeconomic comparison of an albumin-furosemide complex versus sequential therapy for renal insufficiency

The purpose of this economic analysis was to develop an economic model using intra-institutional cost data for acute, oliguric renal insufficiency treated with either an albumin-furosemide complex or albumin followed by furosemide (sequential therapy). The perspective of this study was from the standpoint of the institution (University Medical Center, a teaching hospital). The decision tree and sensitivity analyses demonstrated that the albumin-furosemide complex would be more effective and less costly than sequential therapy for a range of outcome probabilities. Using effectiveness assumptions from published literature, the complex could avoid dialysis in 27% of patients compared with 8% of patients receiving sequential therapy. The complex would also be less costly ($7778 vs $8748). In terms of cost-effectiveness, the complex is $28,807 per averted dialysis compared with $109,350 for sequential therapy.

Effect of bolus injection versus continuous infusion of furosemide on diuresis and neurohormonal activation in patients with severe congestive heart failure

Previous studies have demonstrated that continuous infusion of furosemide results in increased diuresis and natriuresis compared with bolus administration of the drug in patients with severe heart failure. We reasoned that continuous infusion of furosemide caused less activation of neurohumoral mechanisms, since other studies have shown that bolus administration of furosemide may activate this system. We therefore tested the hypothesis that continuous administration of furosemide would increase water and sodium excretion due to less activation of neurohormones. Eight patients with severe heart failure were studied during continuous infusion over 24 h and bolus injections of furosemide twice daily in a randomized cross-over study. Bolus administration of furosemide increased diuresis and natriuresis significantly in the first 4 h after administration compared with continuous administration, but this was later reversed, resulting in similar 24 h total output. The neurohormones measured at baseline were all markedly elevated. Neither regimens of furosemide caused any further significant changes in neurohumoral response except that pro-ANF decreased more during the first 8 h after bolus administration compared to continuous infusion. This study has demonstrated that bolus administration of furosemide in conventional doses is equally effective as continuous intravenous infusion in patients with severe heart failure. This may be due to maximal neurohormonal activation in severe heart failure (NYHA III-IV) which could not be further activated by bolus administration.

Molecular and clinical implications of loop diuretic ototoxicity

Recent advances in molecular biology have been applied to inner ear research. Loop diuretic ototoxicity has been suggested, but not proven, to share a common mechanism with diuretic effects on renal tubules. The discovery of the molecular nature of the Na-K-2Cl cotransporter in the cochlea provided a better understanding of loop diuretic ototoxicity. In this review, we describe clinical reports of loop diuretic ototoxicity and other information obtained by physiological, biochemical and morphological investigations related to the mechanism sensitive to loop diuretics. Based on recent evidence for the molecular nature of the Na-K-2Cl cotransporter expressed in the mammalian cochlea, the underlying mechanisms of ototoxicity induced by loop diuretics are described.

Grand Rounds--City Hospital, Nottingham. A complicated case of community acquired pneumonia

Images

Continuous infusion of furosemide in the treatment of patients with congestive heart failure and diuretic resistance

OBJECTIVES

To assess the value of treatment with continuous intravenous infusion of furosemide (F) in patients with refractory congestive heart failure.

DESIGN

Open uncontrolled dose-response study.

SUBJECTS

Patients with congestive heart failure (those with New York Heart Association (NYHA) classes III and IV with an assessed amount of oedema of more than 5 kg and diuretic resistance were included [n = 10]). Diuretic resistance was defined as: failure to lose weight and/or inappropriate urinary sodium excretion (50 mmol 24 h-1) despite bed rest for a period of 2-3 days, salt and water restriction, orally and intravenously administered furosemide in a dose of 250 mg day-1, digoxin, and when possible an ACE inhibitor. Included patients were treated with continuous F infusion at a delivery rate of 20 mg-1 over 24 h. The infusion rate was gradually heightened up to a maximum dose of 160 mg h-1.

MAIN OUTCOME MEASURES

Daily physical examination, history of side-effects, determination of serum electrolytes and 24-h electrolyte excretion during treatment with furosemide.

RESULTS

Weight loss (mean +/- SD; 12.5 +/- 5 kg) and relief of symptoms was achieved in all patients. Mean (+/- SD) 24-h sodium output rose from 19 +/- 16 mmol 24 h-1 (n = 10) on oral therapy with 250 mg F to 137 +/- 85 mmol 24 h-1 (n = 8) during 80 mg h-1 and to 268 +/- 124 mmol 24 h-1 (n = 3) on the maximal dose of 160 mg h-1.

CONCLUSION

Continuous infusion of F under careful monitoring of the patient is a safe, controllable and efficient treatment in patients with severe congestive heart failure and diuretic resistance.

Dose-response relationships for furosemide ototoxicity in rat

Furosemide is an ototoxic loop diuretic which is highly bound to serum albumin. Previous studies have shown that rats deficient in albumin are more susceptible to furosemide ototoxicity than are rats with normal serum albumin concentrations. The present study was designed to compare the dose-response relationships for furosemide ototoxicity in rats with normal serum albumin concentration to rats without albumin in their serum. Young adult rats 50-80 days of age from each group were anesthetized with Rompun, and the endocochlear potential (EP) and compound action potential (CAP) thresholds were measured before and after furosemide injection. Afer a stable EP and CAP threshold were measured, each animal was injected with a single dose of furosemide through a cannula in the jugular vein. Rats with normal serum albumin had very little change in the EP or CAP threshold until the dose of furosemide was 40 mg/kg or greater. The dose-response curves for EP reduction and CAP threshold elevation then rose steeply to reach a maximum at 50 mg/kg. Albumin-deficient rats were much more sensitive to the effects of furosemide. The dose-response curves for both EP and CAP were shifted to the left. The doses resulting in half-maximal effects in the albumin-deficient rats were about half that found in the normal rats. These findings support the hypothesis that the access of furosemide to its site of ototoxic action in the cochlea depends on the quantity of unbound furosemide in the serum.

Pharmacokinetics of furosemide in endolymph

To investigate the pharmacokinetics of organic anions in the endolymph of the guinea pig, 100 mg/kg furosemide, an organic anion, was intravenously given to measure the concentration in the cochlear endolymph by high-performance liquid chromatography with fluorescence detection. In the endolymph, the concentration of the furosemide increased slowly for 1 hr to 1.6 micrograms/ml and gradually declined thereafter. Pretreatment with 200 mg/kg probenecid, an anion transport inhibitor, had no effect on the furosemide elimination in the endolymph except on the concentration at 2 hr. This was contrary to the drastic change observed in the perilymph of the scala tympani by the same pretreatment. Analogous to the effect in the endolymph, probenecid showed no change in the concentration of the serum, while a pronounced gradient of furosemide concentration existed between them. The present results suggest that the furosemide passively transfers from blood to the endolymph at a relatively low penetrability.

Comparative acute ototoxicity of loop diuretic compounds

A microelectrode was used to measure endocochlear potentials (EP) in adult chinchillas and to study the effects of a series of loop diuretics. EP was measured before, during and for several hours after the intravenous injection of the following loop diuretics: furosemide, piretanide, bumetanide, ethacrynic acid, indacrinone stereoisomers and ozolinone. The first four loop diuretics caused a substantial dose-related reduction of EP. The (-) isomer of indacrinone was found to cause a dose-related reduction of EP to a moderate degree. The (+) isomer of indacrinone and ozolinone caused very little change of EP, even in very high doses. Findings are consistent with data on the mechanism of action of these agents in the kidney.