Overview of pharmacologic agents for acid suppression in critically ill patients

Proton Pump Inhibitors Worsen Colorectal Cancer Outcomes in Patients Treated with Bevacizumab

BACKGROUND

Approximately one-third of patients with advanced colorectal cancer (CRC) and treated with bevacizumab are prescribed proton pump inhibitors (PPIs) or H2 receptor antagonists (H2RAs). However, there is limited data on the effects of PPIs and H2RAs in these patients. To investigate the oncological outcomes of PPI and H2RA use in CRC patients treated with bevacizumab, we performed a retrospective cohort study using the Taiwan National Health Insurance Research Database and Taiwan Cancer Registry Database from 2005 to 2020.

METHODS

In CRC patients treated with bevacizumab, the PPI users and H2RA users were matched with patients without acid-reducing agents (ARAs) by 1:4 propensity score matching. PPI users and H2RA users were matched with propensity scoring in a 1:1 ratio. We divided patients into 4 cumulative PPI dosage levels to assess the dose-response relationship. The primary endpoints were 5-year overall survival and cancer-specific survival.

RESULTS

Compared with ARA non-users, both H2RA users and PPI users were associated with reduced overall survival. PPI users were associated with more significant negative effects on overall survival. Compared with H2RA users, PPI users were associated with lower 5-year overall survival (aHR: 1.19, 95% CI: 1.09-1.31) and cancer-specific survival (aHR: 1.20, 95% CI: 1.09-1.31). A similar dose-response relationship was observed for PPI users in terms of 5-year overall survival and cancer-specific overall survival.

CONCLUSIONS

Compared to H2AR use, PPI use was associated with dose-dependent poorer oncological outcomes in metastatic CRC patients treated with bevacizumab.

Population Pharmacokinetics of Posaconazole in Immune-Compromised Children and Assessment of Target Attainment in Invasive Fungal Disease

BACKGROUND AND OBJECTIVE

Posaconazole (PSZ) is a triazole antifungal for the management of invasive fungal disease (IFD) in adults and children. Although PSZ is available as an intravenous (IV) solution, oral suspension (OS) and delayed-release tablets (DRTs), OS is the preferred formulation for pediatric use because of potential safety concerns associated with an excipient in the IV formulation and difficulty in swallowing intact tablets by children. However, poor biopharmaceutical characteristics of the OS formulation leads to an unpredictable dose-exposure profile of PSZ in children, potentially risking therapeutic failure. The goal of this study was to characterize the population pharmacokinetics (PK) of PSZ in immunocompromised children and assess therapeutic target attainment.

METHODS

Serum concentrations of PSZ were collected retrospectively from records of hospitalized patients. A population PK analysis was performed in a nonlinear mixed-effects modeling framework with NONMEM (v7.4). The PK parameters were scaled to body weight, then potential covariate effects were assessed. The final PK model was used to evaluate recommended dosing schemes through simulation of target attainment (as a percentage of the population having steady-state trough concentrations above the recommended target) using Simulx (v2021R1).

RESULTS

Repeated measurement data of 202 serum concentrations of total PSZ were acquired from 47 immunocompromised patients between 1 and 21 years of age receiving PSZ either intravenously or orally, or both. A one-compartment PK model with first-order absorption and linear elimination best fit the data. The estimated absolute bioavailability (95% confidence interval) for suspension (Fs) was 16% (8-27%), which was significantly lower than the reported tablet bioavailability (Ft) [67%]. Fs was reduced by 62% and 75% upon concomitant administration with pantoprazole (PAN) and omeprazole (OME), respectively. Famotidine resulted in a reduction of Fs by only 22%. Both fixed dosing and weight-based adaptive dosing provided adequate target attainment when PAN or OME were not coadministered with the suspension.

CONCLUSIONS

The results of this study revealed that both fixed and weight-based adaptive dosing schemes can be appropriate for target attainment across all PSZ formulations, including suspension. Additionally, covariate analysis suggests that concomitant proton pump inhibitors should be contraindicated during PSZ suspension dosing.

Best Practices in Treatment of Laryngopharyngeal Reflux Disease: A Multidisciplinary Modified Delphi Study

BACKGROUND

Laryngopharyngeal reflux (LPR) is a common otolaryngologic diagnosis. Treatment of presumed LPR remains challenging, and limited frameworks exist to guide treatment.

METHODS

Using RAND/University of California, Los Angeles (UCLA) Appropriateness Methods, a modified Delphi approach identified consensus statements to guide LPR treatment. Experts independently and blindly scored proposed statements on importance, scientific acceptability, usability, and feasibility in a four-round iterative process. Accepted measures reached scores with ≥ 80% agreement in the 7-9 range (on a 9-point Likert scale) across all four categories.

RESULTS

Fifteen experts rated 36 proposed initial statements. In round one, 10 (27.8%) statements were rated as valid. In round two, 8 statements were modified based on panel suggestions, and experts subsequently rated 5 of these statements as valid. Round three's discussion refined statements not yet accepted, and in round four, additional voting identified 2 additional statements as valid. In total, 17 (47.2%) best practice statements reached consensus, touching on topics as varied as role of empiric treatment, medication use, lifestyle modifications, and indications for laryngoscopy.

CONCLUSION

Using a well-tested methodology, best practice statements in the treatment of LPR were identified. The statements serve to guide physicians on LPR treatment considerations.

Cimetidine-Based Cationic Amphiphiles for In Vitro Gene Delivery Targetable to Colon Cancer

Cimetidine, a histamine-2 (H2) receptor antagonist, has been found to have anticancer properties against a number of cancer-type cells. In this report, we have demonstrated that cimetidine can acts as a hydrophilic domain in cationic lipids and targetable to the gastric system by carrying reporter genes and therapeutic genes through in vitro transfection. Two lipids, namely, Toc-Cim and Chol-Cim consisting cimetidine as the main head group and hydrophobic moieties as alpha-tocopherol or cholesterol, respectively, were designed and synthesized. 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) is a well-known co-lipid employed to produce liposomes as uniform vesicles. The liposomes and lipoplexes were structurally and functionally evaluated for global surface charges and hydrodynamic diameters, and results found that both liposome and lipoplex size and surface charges are optimal to screen the transfection potentials. DNA-binding studies were analyzed as complete binding at all formulated N/P ratios. The liposomes and lipoplexes of both the lipids Toc-Cim and Chol-Cim show minimal cytotoxicity even though at higher concentrations. The results of the transfection experiments revealed that tocopherol-based cationic lipids (Toc-Cim) show finer transfection efficacy with optimized N/P ratios (2:1 and 4:1) in the colon cancer cell line. Toc-Cim lipoplexes show higher cellular uptake compare to Chol-Cim in the colon cancer cell line at 2:1 and 4:1 N/P ratios. Toc-Cim and Chol-Cim lipids showed highly compatible serum, examined up to 50% of the serum concentration. To evaluate the apoptotic cell death in CT-26 cells, exposed to Toc-Cim:p53 and Chol-Cim:p53 lipoplexes at 2:1 N/P ratios, superior results showed with Toc-Cim:p53. An effect of TP53 protein expression in CT-26 cell lines assayed by western blot, transfected with Toc-Cim:p53 and Chol-Cim:p53 lipoplexes, demonstrated the superior efficacy of Toc-Cim. All of the findings suggest that Toc-Cim lipid is relatively secure and is an effective transfection agent to colon cancer gene delivery.

Are Proton Pump Inhibitors More Effective Than Histamine-2-Receptor Antagonists for Stress Ulcer Prophylaxis in Critically Ill Patients? A Systematic Review and Meta-Analysis of Cohort Studies

BACKGROUND

Histamine-2-receptor antagonists (H₂RAs) have been largely replaced by proton pump inhibitors (PPIs) for stress ulcer prophylaxis (SUP) despite the inconclusive evidence concerning comparative effectiveness.

OBJECTIVE

To compare the effectiveness of PPIs and H₂RAs on SUP in real-world setting.

METHODS

PubMed, Embase, and the Cochrane Library were searched from inception to September 19, 2021. We included cohort studies comparing PPIs with H₂RAs in critically ill adult patients and explicitly reporting the outcome of gastrointestinal (GI) bleeding or mortality. Newcastle-Ottawa Scale was used to assess potential risk of bias. We conducted a random-effects meta-analysis and only the studies with adjusted effect estimates were pooled. The Grading of Recommendations Assessment, Development, and Evaluation system was used to assess the overall quality of the evidence.

RESULTS

Thirteen cohort studies (N = 145 149) were eligible and 11 of them available for full texts were of low to moderate risk of bias. Meta-analysis of adjusted effect estimates indicated that PPIs were associated with a significantly higher risk of GI bleeding, compared with H₂RAs (8 studies, odds ratio [OR] = 1.98, 95% confidence interval [CI] = 1.30-3.01, low certainty). Post hoc pooling analysis also suggested that PPIs were associated with a slightly higher risk of mortality in comparison with H₂RAs (7 studies, OR = 1.27, 95% CI = 1.13-1.42, low certainty).

CONCLUSION AND RELEVANCE

The systematic review of cohort studies showed that PPIs were associated with higher risks of GI bleeding and mortality, although the certainty of evidence was low. Overall, we suggest not excluding H₂RAs for SUP, while further studies are essential for elucidating the risk stratification, optimal regimen, and specific duration.

Interactions between epidermal growth factor receptor tyrosine kinase inhibitors and proton-pump inhibitors/histamine type-2 receptor antagonists in non-small cell lung cancer: a systematic review and meta-analysis

Background

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are increasingly used for advanced non-small cell lung cancer (NSCLC) as first-line therapy. The bioavailability and efficacy of oral EGFR-TKIs could be affected by acid suppression (AS) therapy such as PPIs and H2RAs which are reported to be over-prescribed. Hence, there is a need to investigate the effect of AS on the overall survival (OS), progression-free survival (PFS) and adverse effect profile in patients treated with EGFR TKIs.

Methods

An electronic database search of Medline and Embase was performed following PRISMA guidelines on 17 January 2021. Studies analyzing interactions between EGFR TKIs and PPIs/H2RAs in NSCLC patients were included. Abstracts, non-English or non-Japanese studies or studies using non-EGFR TKIs were excluded. Hazard ratios (HRs) were pooled using generic inverse variance random effects model. Effect sizes for dichotomous variables were pooled using Mantel-Haenszel random effects model. Significance was considered at P≤0.05. Heterogeneity was assessed with Cochran Q-test and I2 test. Publication bias was assessed with funnel plots. The assessment of quality and risk of bias of randomized and non-randomized studies were undertaken with RoB 2 and the ROBINS-I tool respectively.

Results

Out of 1,173 potentially relevant articles, 14 articles were included in the final analysis. The pooled prevalence of AS in patients taking EGFR TKI was 30.71% in 4,010 individuals. Patients who were treated only with EGFR TKI had significantly better OS (HR =1.46, 95% CI: 1.27–1.72; P<0.00001) and PFS (HR =1.63, 95% CI: 1.35–1.98; P<0.00001). The OS for EGFR mutation positive patients only was as similarly significant as the OS in all patients taking EGFR TKI, while the PFS in mutation positive patients was significantly worsened with AS. PPIs resulted in a significantly worsened OS and PFS but H2RAs did not produce significantly different OS and PFS between AS and non-AS users. There were no significant differences in the incidence of rash (OR =0.81, 95% CI: 0.50–1.32; P=0.40), diarrhoea (OR =1.03, 95% CI: 0.63–1.67; P=0.91) or other adverse effects.

Conclusions

Co-administration of AS medications with first-generation EGFR-TKIs in NSCLC worsens survival outcomes. Physicians should only prescribe AS medications when absolutely clinically indicated.

Cimetidine promotes STUB1-mediated degradation of tumoral FOXP3 by activating PI3K-Akt pathway in gastric cancer

Background

Previous studies have confirmed the antitumor effects of cimetidine, while the therapeutic targets and the mechanisms are not yet fully understood. We previously reported the protumoral role of endogenous FOXP3 in gastric cancer (GC), but whether cimetidine plays an antitumor role by targeting FOXP3 is still unknown.

Methods

A series of assays were used to examine the role of cimetidine on the malignant behaviors and the expression of endogenous FOXP3 in GC cells. The role of cimetidine on ligase E3-STUB1and the role of STUB1 on FOXP3 level were examined, with the signaling pathway involved in these processes also being explored.

Results

Cimetidine inhibited the malignant behaviors of GC cells, and led to the ubiquitination/degradation of FOXP3. Moreover, cimetidine promoted STUB1 expression, STUB1 knockdown rescued the decline of FOXP3 in cimetidine-treated GC cells, and reduced the turnover effect of cimetidine on GC cells, but had minimal effect in untreated cells. Immunoprecipitation (IP) assay confirmed the formation of the STUB1-FOXP3 complex in cimetidine-treated GC cells. Furthermore, Cimetidine promoted STUB1 expression by activating PI3K/Akt pathway, and the inhibition of PI3K/Akt pathway rescued the decline of FOXP3 by suppressing the upregulation of STUB1.

Conclusions

Cimetidine suppressed GC development by promoting STUB1-mediated ubiquitination/degradation of endogenous FOXP3 through the activation of the PI3K/Akt pathway.

Pharmacologic Prophylaxis of Stress Ulcer in Non-ICU Patients: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

PURPOSE

Acid-suppressive medications are widely used in non-intensive care unit (non-ICU) patients for stress ulcer (SU) prophylaxis. However, SU prophylaxis in this population is still controversial. The purpose of this study was to systematically evaluate the efficacy and tolerability of these agents for SU prophylaxis in non-ICU patients.

METHODS

Electronic databases including Cochrane, ClinicalTrials.gov, Ovid-Medline, Embase, Chinese CNKI, and Wanfang Data were systematically searched on July 10, 2019, for randomized controlled trials (RCTs) that evaluated acid-suppressive medications in non-ICU patients. Network meta-analysis and pairwise meta-analysis were performed to calculate odds ratios (ORs) and 95% CIs. A random-effects model was used for generating pooled estimates. The primary outcome was occurrence of SU bleeding, and the adverse drug events (ADEs) were described as the secondary outcome.

FINDINGS

A total of 17 RCTs involving 1985 patients were eligible. Meta-analysis results indicated that the occurrence of SU bleeding was significantly decreased with all acid-suppressive medications compared with placebos (gastric mucosa protectants, OR = 0.29 [95% CI, 0.14-0.61]; H2-receptor antagonists, OR = 0.3 [95% CI, 0.18-0.50]; proton pump inhibitors [PPIs]: OR = 0.08 [95% CI, 0.04-0.16]). The occurrence of SU bleeding was significantly decreased with PPIs compared with gastric mucosa protectants (OR = 0.29; 95% CI, 0.12-0.72) and H2-receptor antagonists (OR = 0.28; 95% CI, 0.16-0.48). There was no significant difference between any 2 classes of PPIs on SU bleeding or any 2 acid-suppressive medications on ADEs.

IMPLICATIONS

PPIs could significantly decrease SU bleeding risk without increasing ADEs than other acid-suppressive medications for SU prophylaxis in non-ICU patients. However, RCTs of high quality were required to confirm the findings of this investigation.

Acid-Suppressive Therapy and Risk of Infections: Pros and Cons

This narrative review summarises the benefits, risks and appropriate use of acid-suppressing drugs (ASDs), proton pump inhibitors and histamine-2 receptor antagonists, advocating a rationale balanced and individualised approach aimed to minimise any serious adverse consequences. It focuses on current controversies on the potential of ASDs to contribute to infections-bacterial, parasitic, fungal, protozoan and viral, particularly in the elderly, comprehensively and critically discusses the growing body of observational literature linking ASD use to a variety of enteric, respiratory, skin and systemic infectious diseases and complications (Clostridium difficile diarrhoea, pneumonia, spontaneous bacterial peritonitis, septicaemia and other). The proposed pathogenic mechanisms of ASD-associated infections (related and unrelated to the inhibition of gastric acid secretion, alterations of the gut microbiome and immunity), and drug-drug interactions are also described. Both probiotics use and correcting vitamin D status may have a significant protective effect decreasing the incidence of ASD-associated infections, especially in the elderly. Despite the limitations of the existing data, the importance of individualised therapy and caution in long-term ASD use considering the balance of benefits and potential harms, factors that may predispose to and actions that may prevent/attenuate adverse effects is evident. A six-step practical algorithm for ASD therapy based on the best available evidence is presented.

Inhibition of lysosomal enzyme activities by proton pump inhibitors

BACKGROUND

Proton pump inhibitors (PPIs) are pro-drugs requiring an acidic pH for activation. The specificity of PPI toward the proton pump is mainly due to the extremely low pH at the parietal cell canalicular membrane where the pump is located. Reactivity of PPIs was also observed in moderately acidic environments like the renal collecting duct. But no PPI effect on lysosomal enzymes has been observed possibly because the previous studies were performed with liver tissue, where PPIs are metabolized.

METHODS

The reactivity of PPIs (omeprazole, lansoprazole and pantoprazole) with a cysteine-containing peptide was analyzed by mass spectrometry, and the impact of PPIs on lysosomal enzymes was evaluated in cultured cells and mice. The effect of PPIs on the immune system was examined with a mouse tumor immunotherapy model.

RESULTS

Incubation of a cysteine-containing peptide with PPIs at pH5 led to the conversion of most of the peptide into PPI-peptide adducts. Dose dependent inhibition of lysosomal enzyme activities by PPIs was observed in cultured cells and mouse spleen. Further, PPI counteracted the tumor immunotherapy in a mouse model.

CONCLUSIONS

Our data support the hypothesis that many of the PPI adverse effects are caused by systematically compromised immunity, a result of PPI inhibition of the lysosomal enzymes. This novel mechanism complements the existing mechanisms in explaining the increased incidence of tumorigenesis and infectious diseases among PPI users and underlie the ongoing concern about the overuse of PPIs in adult and pediatric populations.

Decreased acid suppression therapy overuse after education and medication reconciliation

BACKGROUND

Acid suppression therapy (AST) is commonly overprescribed in hospitalised patients. This indiscriminate use increases cost and drug-related side effects. Minimal data is available on interventions aimed at reducing the burden of overprescription. The aim of our study was to evaluate the impact of education and medication reconciliation forms use on admission as well as discharge, on AST overuse in hospitalised patients.

METHODS

A retrospective chart review of randomly selected patients admitted to the general medicine service at University of Florida Health Science Center/Jacksonville was performed prior to and after the introduction of interventions (education/medication reconciliation) aimed at reducing AST overuse. The percentage of patients started on inappropriate AST, the admitting diagnosis, indications for starting AST and discharge on these medications was compared in the pre and postintervention groups.

RESULTS

Acid suppression therapy use declined from 70% (279/400) in the preintervention period to 37% (100/270) postintervention (p < 0.001). There was a reduction in inappropriate prescriptions from 51% (204/400) pre to 22% (60/270) postintervention (p < 0.02). Stress ulcer prophylaxis in low-risk patients or the concomitant use of ulcerogenic drugs continued to motivate inappropriate AST therapy in most patients. Postintervention, only 20% (12/60) of patients were discharged on unneeded AST compared with 69% (140/204) in the preintervention group (p < 0.001).

CONCLUSION

Interventions consisting of education and use of medication reconciliation forms decreased inappropriate prescription of AST on admission and discharge. This can significantly decrease cost to the healthcare system and the risk of drug interactions.

The efficacy and safety of proton pump inhibitors vs histamine-2 receptor antagonists for stress ulcer bleeding prophylaxis among critical care patients: a meta-analysis

OBJECTIVE

To examine the efficacy and safety of proton pump inhibitors in comparison with histamine-2 receptor antagonists for stress-related upper gastrointestinal bleeding prophylaxis among critical care patients.

DATA SOURCES

PubMed, EMBASE, Cochrane Library, and ClinicalTrials.gov.

STUDY SELECTION

Randomized, controlled trials that directly compare proton pump inhibitors with histamine-2 receptor antagonists in prevention of stress-related upper gastrointestinal bleeding in intensive care unit patients published before May 30, 2008.

DATA EXTRACTION

Two reviewers independently applied selection criteria, performed quality assessment, and extracted data. The primary outcome was the incidence of stress-related upper gastrointestinal bleeding, and the secondary outcome measures were the incidence of pneumonia and intensive care unit mortality.

DATA SYNTHESIS

The random effect model was used to estimate the pooled risk difference between two treatment arms irrespective of drug, dosage, and route of administration.

RESULTS

We identified seven randomized, controlled trials with a total of 936 patients for planned comparison. The overall pooled risk difference (95% confidence interval; p value; I statistics) of stress-related upper gastrointestinal bleeding comparing proton pump inhibitors vs. histamine-2 receptor antagonists was -0.04 (95% confidence interval, -0.09-0.01; p = .08; I = 66%). In the sensitivity analysis, removing the Levy study significantly reduced the heterogeneity (from I = 66% to I = 26%) and shifted the overall risk difference closer to the null (pooled risk difference, -0.02; 95% confidence interval, -0.05-0.01; p = .19). There was no difference between proton pump inhibitors and histamine-2 receptor antagonists therapy in the risk of pneumonia and intensive care unit mortality, with pooled risk differences of 0.00 (95% confidence interval, -0.04-0.05; p = .86; I = 0%) and 0.02 (95% confidence interval, -0.04-0.08; p = .50; I = 0%), respectively.

CONCLUSIONS

This meta-analysis did not find strong evidence that proton pump inhibitors were different from histamine-2 receptor antagonists in terms of stress-related upper gastrointestinal bleeding prophylaxis, pneumonia, and mortality among patients admitted to intensive care units. Because of limited trial data, future well-designed and powerful randomized, clinical trials are warranted.

Safety of probiotics in patients receiving nutritional support: a systematic review of case reports, randomized controlled trials, and nonrandomized trials

BACKGROUND

Probiotics are increasingly used in patients receiving nutritional support; however, some case reports and trials have questioned their safety in such patients.

OBJECTIVE

The objective was to investigate the safety of probiotics in patients receiving nutritional support through a systematic review of case reports, randomized controlled trials (RCTs), and nonrandomized trials.

DESIGN

The systematic review followed Cochrane and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) recommendations. Six electronic databases were searched, a hand search of conference proceedings and reference lists was performed, and experts were contacted. Case reports, RCTs, and nonrandomized trials of probiotic use in patients also receiving enteral or parenteral nutrition were included in the review. Two reviewers independently screened the relevant articles and extracted the data.

RESULTS

In total, 1966 articles were identified, of which 72 fulfilled the inclusion criteria. There were 20 case reports of adverse events in 32 patients, all of which were infections due to Lactobacillus rhamnosus GG or Saccharomyces boulardii; the risk factors included central venous catheters and disorders associated with increased bacterial translocation. There were 52 articles reporting 53 trials in which 4131 patients received probiotics. Most trials showed either no effect or a positive effect on outcomes related to safety (eg, mortality and infections). Only 3 trials showed increased complications, which were largely noninfectious in nature and in specific patient groups (eg, transplant and pancreatitis). In 2 of these trials, the probiotic was administered through a postpyloric tube.

CONCLUSION

Many probiotics have been used safely in patients receiving nutritional support, although some probiotic products (strains or combinations) have been shown to increase the risk of complications in specific patient groups.

When should stress ulcer prophylaxis be used in the ICU?

PURPOSE OF REVIEW

To discuss the risk factors and underlying illnesses that play a role in the pathophysiology of stress ulcer, and to evaluate the evidence pertaining to stress ulcer-related bleeding prophylaxis in critically ill patients.

RECENT FINDINGS

The use of stress ulcer prophylaxis is common in critical care medicine and is a major challenge to physicians in the ICU. The mechanism of stress ulcer is believed to be multifactorial, yet remains incompletely understood. The most widely used drugs for stress ulcer prophylaxis are intravenous histamine2-receptor antagonists. They raise gastric pH, but are associated with the development of tolerance, possible drug interactions, and neurologic manifestations. Sucralfate, which can be administered by the nasogastric route, can protect the gastric mucosa without raising pH, but may decrease absorption of concomitantly administered oral medications. Proton pump inhibitors are the most potent acid-inhibiting pharmacologic agents available. Proton pump inhibitors are at least as effective as histamine2-receptor antagonists, as a limited number of clinical trials have demonstrated. However, these trials were small, lacked an active comparator, varied in the number of risk factors, and used a different definition of clinically important bleeding than previously established.

SUMMARY

Routine prophylaxis against stress ulcers in the ICU is not well justified by current evidence. Patients at risk of stress ulcer-related bleeding are most likely to benefit from prophylaxis. Thus, healthcare professionals should continue to evaluate risk and assess the need for stress ulcer-related prophylaxis.

Proton pump inhibitors: actions and reactions

Proton pump inhibitors are the second most commonly prescribed drug class in the United States. The increased utilization of PPIs parallels the rising incidence of reflux disease. Owing to their clinical efficacy and relative lack of tachyphylaxis, PPIs have largely displaced H-2 receptor antagonists in the treatment of acid peptic disorders. The elevation of intragastric pH and subsequent alterations of gastric physiology induced by PPIs may yield undesired effects within the upper GI tract. The ubiquity of the various types of H(+), K(+)-ATPase could also contribute to non-gastric effects. PPIs may influence physiology in other ways, such as inducing transepithelial leak.

Four-day continuous gastric pH monitoring following anti-acid secretory drug administration: cross-over test to assess the early effects

BACKGROUND

There have been few reports that compare the effect of histamine H2-receptor antagonists (H2RAs) and proton pump inhibitors (PPIs) using continuous gastric pH monitoring for a long duration.

AIM

To assess the early effects of both drugs on gastric pH using a wireless pH monitoring system.

METHODS

The test was conducted by a cross-over test: 10 healthy male volunteers were administered famotidine 20 mg twice a day and lansoprazole 30 mg once a day. Monitoring of gastric pH over four consecutive days was performed using a unique method we have developed that is an elaboration of the Bravo system.

RESULTS

The time to reach a pH level of 3 or more with famotidine was significantly shorter than that for lansoprazole. The pH3 holding time ratio of famotidine during the first 4 h of administration was significantly higher than that of lansoprazole. The pH3 holding time ratio on each day from day 1 to day 3 was significantly higher following lansoprazole administration compared with famotidine administration.

CONCLUSIONS

Famotidine was shown to act quickly in elevating gastric pH; however, lansoprazole was superior to famotidine in terms of its ability to elevate gastric pH for a long duration.

New method for long-term monitoring of intragastric pH

AIM: Consecutive monitoring of intragastric pH using the Bravo^® capsule.

METHODS: We put threads through a Bravo^® capsule and then affixed it to the gastric wall by endoscopic hemoclipping in seven subjects. Study data were uploaded to a computer via Datalink every 48 h. In this way, repeated monitoring of intragastric pH was undertaken.

RESULTS: All subjects were able to monitor gastric pH over a 1-wk period, and five for > 2 wk. No complications were encountered during the monitoring. After pH monitoring, we safely retrieved the capsule endoscopically.

CONCLUSION: Clipping a Bravo^® capsule onto the gastric wall enabled long-term intragastric pH monitoring. This is a methodological report of pH monitoring over a period of > 2 wk.

Stability and compatibility of histamine H2-receptor antagonists in parenteral nutrition mixtures

PURPOSE OF REVIEW

To examine the stability and compatibility of histamine H2-receptor antagonists in parenteral nutrition admixtures in order to provide well tolerated and effective therapy.

RECENT FINDINGS

Many stability investigations were carried out before 2005, but no critical appraisal of published data has been undertaken. H2-receptor antagonists are stable in most parenteral nutrition admixtures for 2-48 h, with long-term stability up to 4 weeks claimed for a few combinations. Some earlier data are questionable in the light of more recent analytical technology and pharmaceutical knowledge regarding stability assessment. As stability is dependent upon the source of constituents, we have listed all products tested and their respective manufacturers. A general recommendation is made not to store H2-receptor antagonists in parenteral nutrition for more than 24 h at refrigerated temperature before use.

SUMMARY

Administration of H2-receptor antagonists in parenteral nutrition admixtures has several clinical and economical advantages, but, in order for these benefits to be well tolerated and efficacious, the stability and compatibility of the drugs, as well as the parenteral nutrition components after mixing, have to be ascertained. Factors that influence stability are assessed, the need for more controlled study protocols is evaluated and recommendations are made for safe storage and administration.

Cimetidine use and the risk for prostate cancer: results from the VITAL cohort study

PURPOSE

The histamine-2 (H(2)) blocker cimetidine may alter androgen, zinc, and prolactin levels, which could alter prostate cancer risk. Increased risk for men filling more than 20 cimetidine prescriptions was reported previously. We examined the association between cimetidine use and prostate cancer risk in a cohort in western Washington State.

METHODS

Participants were 33,506 men, 50 to 76 years old, enrolled in the VITamins And Lifestyle cohort (VITAL). H(2)-blocker use during the prior 10 years was self-reported through baseline questionnaire between October 2000 and December 2002. Men were followed up for subsequent prostate cancer by linkage to the Surveillance, Epidemiology and End Results cancer registry. We identified 548 incident invasive prostate cancer cases diagnosed from baseline to December 31, 2003.

RESULTS

Overall, no association between ever use of cimetidine or years of cimetidine use and prostate cancer risk was observed. However, daily cimetidine use for 10 years was associated with increased risk (relative risk, 2.35; 95% confidence interval, 1.05-5.26) compared with nonuse of any H(2) blockers. Use of other H(2) blockers was not associated with prostate cancer.

CONCLUSIONS

Additional studies are needed to determine whether long-term daily cimetidine use is associated with increased prostate cancer risk in other populations, and if so, the reason for this association.

Acid suppressive therapy use on an inpatient internal medicine service

BACKGROUND

Use of acid suppressant medications has increased in both frequency and breadth in recent years. Data have indicated that questionable use of acid suppressants for non-accepted indications is common.

OBJECTIVE

To assess the indications and prevalence of acid suppressants used by inpatients on admission and at discharge.

METHODS

A retrospective chart review of 213 patients admitted to the University of Michigan Hospital non-critical care general medical service was conducted. Relevant medical history, acid suppressant drug used, and indications were collected from both inpatient medical records and discharge medication lists.

RESULTS

Of the 213 patients reviewed, 29% were taking acid suppressants prior to admission, with 33% being proton pump inhibitors (PPIs). Once patients were admitted, acid suppressant use increased to 71% (152 of 213), with 84% PPIs, 11% histamine(2)-receptor antagonists, and 5% combination therapy. Based upon our criteria, only 10% (15 of 152) of those on acid suppressants were found to have an acceptable indication. In patients where any history of gastroesophageal reflux disorder (GERD) was deemed as an acceptable indication (32 other patients), 31% (47 of 152) had an acceptable indication. For the 137 patients with non-accepted indications, 29% had no discernable indication and 38% were prescribed acid suppressants for corticosteroid-associated or stress ulcer prophylaxis. A history of gastrointestinal bleeds or peptic ulcer disease of more than 3 months since initial diagnosis or documented exacerbation of symptoms comprised 8% of the population. The aforementioned group of GERD patients made up 23% of this group. Compared to the 29% of patients taking acid suppressants prior to admission, 54% (115 of 213) of patients were prescribed acid suppressants at discharge. If only recent exacerbations of GERD were deemed as long-term indications, 10% (12 of 115) of these patients were found to have accepted indications. If all GERDs were acceptable long-term indications, 27% (31 of 115) would have met criteria for acceptable outpatient use.

CONCLUSIONS

There is considerable excess usage of acid suppressants in both the inpatient and outpatient settings.