Safety of metamizole: a systematic review of the literature

Chronic pain, a narrative review for the internist in 2024

Chronic pain is a complex and pervasive condition that profoundly affects individuals physically, emotionally, and socially. This narrative review aims to provide internists and healthcare professionals with a comprehensive overview of chronic pain, its various types, pathophysiology, epidemiology, clinical presentation, evaluation tools, and the burden it imposes on patients. We discuss the importance of recognizing chronic pain as a legitimate condition and the need for a compassionate, individualized approach to management. The review highlights the role of both pharmacological and non-pharmacological interventions in treating chronic pain, emphasizing the value of reducing pain, improving function, enhancing quality of life, and minimizing medication dependence. Additionally, we touch upon the promising future of pain treatment, including advancements in technology and personalized medicine. While not a comprehensive systematic review, this article serves as a valuable resource for healthcare providers seeking to understand, manage, and treat chronic pain effectively in their daily practice.

Prediction Models for Adverse Drug Reactions During Tuberculosis Treatment in Brazil

BACKGROUND

Tuberculosis (TB) treatment-related adverse drug reactions (TB-ADRs) can negatively affect adherence and treatment success rates.

METHODS

We developed prediction models for TB-ADRs, considering participants with drug-susceptible pulmonary TB who initiated standard TB therapy. TB-ADRs were determined by the physician attending the participant, assessing causality to TB drugs, the affected organ system, and grade. Potential baseline predictors of TB-ADR included concomitant medication (CM) use, human immunodeficiency virus (HIV) status, glycated hemoglobin (HbA1c), age, body mass index (BMI), sex, substance use, and TB drug metabolism variables (NAT2 acetylator profiles). The models were developed through bootstrapped backward selection. Cox regression was used to evaluate TB-ADR risk.

RESULTS

There were 156 TB-ADRs among 102 of the 945 (11%) participants included. Most TB-ADRs were hepatic (n = 82 [53%]), of moderate severity (grade 2; n = 121 [78%]), and occurred in NAT2 slow acetylators (n = 62 [61%]). The main prediction model included CM use, HbA1c, alcohol use, HIV seropositivity, BMI, and age, with robust performance (c-statistic = 0.79 [95% confidence interval {CI}, .74-.83) and fit (optimism-corrected slope and intercept of -0.09 and 0.94, respectively). An alternative model replacing BMI with NAT2 had similar performance. HIV seropositivity (hazard ratio [HR], 2.68 [95% CI, 1.75-4.09]) and CM use (HR, 5.26 [95% CI, 2.63-10.52]) increased TB-ADR risk.

CONCLUSIONS

The models, with clinical variables and with NAT2, were highly predictive of TB-ADRs.

Changing patterns in the epidemiology of drug allergy

Drug allergy (DA) remains a complex and unaddressed problem worldwide that often deprives patients of optimal medication choices and places them at risk for life-threatening reactions. Underdiagnosis and overdiagnosis are common and due to the lack of standardized definitions and biomarkers. The true burden of DA is unknown, and recent efforts in data gathering through electronic medical records are starting to provide emerging patterns around the world. Ten percent of the general population engaged in health care claim to have a DA, and the most common label is penicillin allergy. Up to 20% of emergency room visits for anaphylaxis are due to DA and 15%-20% of hospitalized patients report DA. It is estimated that DA will increase based on the availability and use of new and targeted antibiotics, vaccines, chemotherapies, biologicals, and small molecules, which are aimed at improving patient's options and quality of life. Global and regional variations in the prevalence of diseases such as human immunodeficiency virus and mycobacterial diseases, and the drugs used to treat these infections have an impact on DA. The aim of this review is to provide an update on the global impact of DA by presenting emerging data on drug epidemiology in adult and pediatric populations.

The Adequacy of Anesthesia Guidance for Vitreoretinal Surgeries with Preemptive Paracetamol/Metamizole

Despite the possibility of postoperative pain occurrence, in some patients, vitreoretinal surgeries (VRSs) require performance of general anesthesia (GA). The administration of intraoperative intravenous rescue opioid analgesics (IROA) during GA constitutes a risk of perioperative adverse events. The Adequacy of Anesthesia (AoA) concept consists of an entropy electroencephalogram to guide the depth of GA and surgical pleth index (SPI) to optimize the titration of IROA. Preemptive analgesia (PA) using cyclooxygenase-3 (COX-3) inhibitors is added to GA to minimize the demand for IROA and reduce postoperative pain. The current analysis evaluated the advantage of PA using COX-3 inhibitors added to GA with AoA-guided administration of IROA on the rate of postoperative pain and hemodynamic stability in patients undergoing VRS. A total of 165 patients undergoing VRS were randomly allocated to receive either GA with AoA-guided IROA administration with intravenous paracetamol/metamizole or with preemptive paracetamol or metamizole. Preemptive paracetamol resulted in a reduction in the IROA requirement; both preemptive metamizole/paracetamol resulted in a reduced rate of postoperative pain as compared to metamizole alone. We recommend using intraoperative AOA-guided IROA administration during VRS to ensure hemodynamic stability alongside PA using both paracetamol/metamizole to reduce postoperative pain.

Analysis of Pain Management after Anatomic VATS Resection in Austrian Thoracic Surgery Units

BACKGROUND

Postoperative pain influences rehabilitation, postoperative complications and quality of life. Despite its impact, there are no uniform treatment guidelines. Different centers seem to use various strategies. This study aims to analyze pain management regimens used after anatomic VATS resections in Austrian thoracic surgery units, with a special interest in opioid usage and strategies to avoid opioids.

METHODS

A questionnaire was designed to assess the use of regional anesthesia, postoperative pain medication and characteristics of individual pain management regimens. The questionnaire was sent to all thoracic surgery units in Austria, with nine out of twelve departments returning them.

RESULTS

All departments use regional anesthesia during the procedure. Four out of nine centers use epidural analgesia or an intercostal catheter for postoperative regional anesthesia in at least 50% of patients. Two departments follow an opioid restrictive regimen, five depend on the visual analogue scale (VAS) and two administer opioids on a fixed schedule. Three out of nine departments use NSAIDs on a fixed schedule. The most used medication is metamizole (eight out of nine centers; six on a fixed schedule, two depending on VAS) followed by piritramide (six out of nine centers; none as a fixed prescription).

CONCLUSIONS

This study reflects the heterogeneity in postoperative pain treatment after VATS anatomic lung resections. All departments use some form of regional anesthesia in the perioperative period; prolonged regional anesthesia is not utilized uniformly to reduce opioid consumption, as suggested in enhanced recovery after surgery programs. More evidence is needed to optimize and standardize postoperative pain treatment.

Epidemiology of anaphylaxis: is the trend still going up?

PURPOSE OF REVIEW

To understand the current global scale of anaphylaxis and identify possible strategies to increase the accuracy of epidemiological data.

RECENT FINDINGS

Anaphylaxis mortality and morbidity statistics may gain new perspectives with the global implementation of the ICD-11. Improving the quality of epidemiological data related to anaphylaxis should clarify some areas of uncertainty about risk factors, leading to better targeting of strategies to protect those patients at risk, and support decision-making to facilitate health care planning and implementation of public health measures to prevent anaphylaxis.

SUMMARY

The true rate of anaphylaxis is unknown due to a number of factors, such as misdiagnosis, miscoding and undernotification. Moreover, there is lack of information about anaphylaxis epidemiology in many countries. Difficulties on collecting accurate and comparable data should be acknowledged and anaphylaxis data can vary widely. Currently, most robust data are derived from hospitalization datasets and national mortality databases. Anaphylaxis accounts for up to 0.26% of overall hospital admissions. It is suggested that the number of hospital admissions for anaphylaxis is increasing in many countries, both with respect to all-causes of anaphylaxis and by trigger, but the mortality rate remains low. However, there are still great challenges in capturing quality anaphylaxis mortality and morbidity statistics. Better understanding of anaphylaxis trends should clarify some areas of uncertainty about risk factors and prospect effective prevention strategies. As the knowledge derived from populations is key information for more realistic decision-making, the construction of the new section addressed to anaphylaxis in the ICD-11 will allow the collection of more accurate epidemiological data to support high quality management of patients, and to better facilitate health care planning to implement public health measures, reduce the morbidity and mortality attributable to anaphylaxis.

Simultaneous application of lidocaine and ketamine during ambulatory infusion therapy: a retrospective analysis

Background: Infusions with lidocaine or ketamine have been separately established in the treatment of chronic pain. This study aims to retrospectively evaluate the effect of combined infusions of lidocaine and ketamine. Materials & methods: Patient records were screened for receipt of combined ambulatory infusions of lidocaine and ketamine from 2012 through 2021. A scoring system was designed to assess pain response retrospectively. Results: A total of 319 patients were included. Median pain reduction in days was 10.00 (interquartile range: 13.25). Side effects were limited to the acute phase of infusions. A total of 41.4% of patients who received concomitant pain medication reported a dose reduction. Conclusion: Our data support combined infusions as a safe therapy option, with good short-, medium- and long-term reductions in pain and great heterogeneity in treatment response. Clinical trial registration: ClinicalTrials.gov (NCT05103319).

Metamizole-induced agranulocytosis (MIA): a mini review

Metamizole is an analgesic, antipyretic, and spasmolytic drug in Germany only approved for the treatment of severe pain or high fever that does not respond to other measures. In recent years, an increased use has been described among both adults and children, often against the approved indication. The most important side effect of metamizole is the development of agranulocytosis (neutrophil count < 500/µL). Incidence of metamizole-induced agranulocytosis (MIA) ranges depending on the study from 0.96 cases per million per year to 1:1602 per patient and metamizole prescription. The risk of agranulocytosis in children remains unclear, but is probably lower than in adults. Female gender and older age are associated with higher incidence, reflecting prescription distribution. MIA is dose-independent and risk seems to increase with duration of intake. In patients with past exposure, re-exposure may lead to rapid onset. MIA is believed to be induced either through immunologic or toxic mechanisms. MIA presents with fever, sore throat, fatigue, and mucosal inflammation, up to ulceration. Even in the case of suspected MIA, treatment with metamizole should be immediately paused and an examination of the blood cell count is required. In case of local or systemic infections, empirical therapy with broad-spectrum antibiotics should be administered. G-CSF therapy should be limited to patients with poor prognostic factors. The patient should be monitored closely until the neutrophil count returns to normal. Re-exposure to metamizole must be avoided.

Parenteral Ready-to-Use Fixed-Dose Combinations Including NSAIDs with Paracetamol or Metamizole for Multimodal Analgesia-Approved Products and Challenges

The combination of non-steroidal anti-inflammatory drugs (NSAIDs) with non-opioid analgesics is common in clinical practice for the treatment of acute painful conditions like post-operative and post-traumatic pain. Despite the satisfactory results achieved by oral analgesics, parenteral analgesia remains a key tool in the treatment of painful conditions when the enteral routes of administration are inconvenient. Parenteral ready-to-use fixed-dose combinations of non-opioid analgesics combinations, including NSAIDs and paracetamol or metamizole, could play a central role in the treatment of painful conditions by combining the advantages of multimodal and parenteral analgesia in a single formulation. Surprisingly, only in 2020, a parenteral ready-to-use fixed-dose combination of ibuprofen/paracetamol was launched to the market. This review aims to investigate the current availability of combinations of NSAIDs with paracetamol or metamizole in both European and American markets, and how the combination of such drugs could play a central role in a multimodal analgesia strategy. Also, we explored how the parenteral formulations of NSAIDs, paracetamol, and metamizole could serve as starting elements for the development of new parenteral ready-to-use fixed-dose combinations. We concluded that, despite the well-recognized utility of combining NSAIDs with paracetamol or metamizole, several randomized clinical trial studies demonstrate no clear advantages concerning their efficacy and safety. Future clinical trials specifically designed to assess the efficacy and safety of pre-formulated fixed-dose combinations are required to generate solid evidence about their clinical advantages.

Potential drug-drug interactions and their associated factors in hospitalized COVID-19 patients with comorbidities

Background

Hospitalized COVID-19 patients with comorbidities receive more complex drug therapy. This increases the probability of potential drug-drug interactions (pDDIs). Studies on pDDIs in hospitalized patients with COVID-19 in countries with limited resources like Indonesia during the later period of the disease are still limited. This study aims to identify the pattern of pDDIs in hospitalized COVID-19 patients with comorbidities and their associated factors, especially in the second wave of the disease in Indonesia.

Methods

This study was a longitudinal-retrospective study observing hospitalized COVID-19 patients with comorbidities using medical record data in June-August 2021 at a public hospital in a region in Indonesia. pDDIs were identified using the Lexicomp^® database. Data were descriptively analyzed. Factors associated with important pDDIs were analyzed in multivariate logistic regression model.

Results

A total of 258 patients with a mean age of 56.99 ± 11.94 years met the inclusion criteria. Diabetes mellitus was the most common comorbidity experienced by 58.14% of the patients. More than 70% of the patients had one comorbidity and the average number of administered drugs was 9.55 ± 2.71 items per patient. Type D pDDIs, which required modification of therapeutic regimens, amounted to 21.55% of the total interactions. Only the number of drugs was significantly and independently associated with type D pDDIs (adjusted odds ratio 1.47 [1.23-1.75], p < 0.01).

Conclusion

The drugs involved in the pDDIs of hospitalized COVID-19 patients with comorbidities may differ depending on the disease periods, hospital settings, or countries. This study was small, single center, and of short duration. However, it may give a glimpse of important pDDIs during the delta variant of COVID-19 in a similar limited-resource setting. Further studies are needed to confirm the clinical significance of these pDDIs.

The Pain Management of Trauma Patients in the Emergency Department

The vast majority of injured patients suffer from pain. Systematic assessment of pain on admission to the emergency department (ED) is a cornerstone of translating the best treatment strategies for patient care into practice. Pain must be measured with severity scales that are validated in clinical practice, including for specific populations (such as children and older adults). Although primary care ED of trauma patients focuses on resuscitation, diagnosis and treatment, pain assessment and management remains a critical element as professionals are not prepared to provide effective and early therapy. To date, most EDs have pain assessment and management protocols that take into account the patient's hemodynamic status and clinical condition and give preference to non-pharmacological approaches where possible. When selecting medications, the focus is on those that are least disruptive to hemodynamic status. Pain relief may still be necessary in hemodynamically unstable patients, but caution should be exercised, especially when using opioids, as absorption may be impaired or shock may be exacerbated. The analgesic dose of ketamine is certainly an attractive option. Fentanyl is clearly superior to other opioids in initial resuscitation and treatment as it has minimal effects on hemodynamic status and does not cause central nervous system depression. Inhaled analgesia techniques and ultrasound-guided nerve blocks are also increasingly effective solutions. A multimodal pain approach, which involves the use of two or more drugs with different mechanisms of action, plays an important role in the relief of trauma pain. All EDs must have policies and promote the adoption of procedures that use multimodal strategies for effective pain management in all injured patients.

Case Report: Simultaneously Induced Neutropenia and Hemolysis After a Single Metamizole Dose

BACKGROUND AND OBJECTIVE

Metamizole is a non-opioid ampyrone sulfonate compound with potent analgesic, antipyretic, and spasmolytic effects. Agranulocytosis is a rare life-threatening complication of metamizole.

CASE

Here, we present the case of a 62-year-old patient who developed agranulocytosis as well as hemolysis after a single administration of metamizole.

CONCLUSION

This case illustrates the inherent allergic potential of metamizole and its effects on different hematopoietic cell types.

Efficacy and safety in ketamine-guided prehospital analgesia for abdominal pain

Abdominal pain is a common reason for presentation in the emergency department and for calling emergency medical services. The complexity of abdominal pain also influences the analgesia strategy. However, there are almost no data on the use of ketamine for abdominal pain. This study aims to analyze the safety and efficacy of using ketamine as an analgesic for abdominal pain. In a retrospective analysis of prehospital patient data within the framework of quality assurance, all cases with ketamine administered by paramedics as analgesia for abdominal pain were analyzed in terms of pain reduction and patient safety and also compared with other analgesic drugs including fentanyl, morphine, and metamizole. From 01/01/2018 to 11/24/2021, 129 datasets were analyzed. The mean patient age was 50 ± 19 years (19-90 years), with 47.3% (n = 61) women. The application of fentanyl was documented as a monotherapy in 10.9% (n = 14), morphine in 2.3% (n = 3), metamizole in 34.1% (n = 44), and ketamine in 52.7% (n = 68) of cases. The pain relief of fentanyl, metamizole, and ketamine differed significantly from each other (p < 0.001), with fentanyl and ketamine being comparable. Looking at the quality assurance definition of successful analgesia (pain on handover NRS < 5 or pain reduction ≥ 2 points), successful analgesia was shown in 92.9% (n = 13) of cases for fentanyl, in 65.9% (n = 44) for metamizole, and 92.6% (n = 68) for ketamine (p < 0.001). Adverse events were not observed in patients treated with ketamine. Analgesia is an important goal in the treatment of patients with abdominal pain. With ketamine, analgesia comparable to fentanyl can be achieved. Ketamine appears to be a safe and effective option for the treatment of patients with abdominal pain in emergency medicine.Trial registration number DRKS00027343, date of registration: 09.12.2021, retrospectively registered.

Liver Transplantation and the Use of Metamizole to Treat Drug-induced Liver Injury

Metamizole, or dipyrone, is a frequently prescribed analgetic drug that can cause drug-induced liver injury (DILI). Still, there are only a few metamizole-associated DILI cases (n = 61, including our study) described in the literature. So far liver transplantation has been reported in 6 patients with metamizole-induced acute liver failure. In 2020, a German group described a bigger cohort (n = 23) of metamizole-related DILI. Shortly thereafter, this issue gained wider attention as the German Federal Institute for Drugs and Medical Devices published a Direct Healthcare Professional Communication, emphasizing DILI as a potential adverse event caused by metamizole. We herein report 2 patients that were admitted to our liver transplant center due to acute liver failure (ALF) in April and May 2021. Both patients reported intake of metamizole as pain medication over a few weeks. After ruling out alternative reasons for ALF and fulfilling the King's College criteria both patients received emergency liver transplantations in our center. Pathology assessment of both explants were consistent with metamizole-associated DILI. As illustrated by our 2 cases of metamizole-induced liver failure with subsequent liver transplantation, this rare but presumably often overlooked adverse drug effect of metamizole should be considered as differential diagnosis in cases of cryptogenic liver failure.

Simultaneous LC-ESI-MS/MS Quantification of Levosimendan and Its Metabolites for Therapeutic Drug Monitoring of Cardiac Surgery Patients

Levosimendan is used in severe chronic cardiac insufficiency, also within the peri-operative setting. Real-life pharmacokinetic data in surgical patients is lacking, making therapeutic drug monitoring (TDM) of levosimendan, its pharmacologically active metabolite OR-1896, and its intermediate OR-1855 important. A simultaneous highly sensitive quantification of levosimendan and its metabolites in small-volume samples has not yet been described. Here, levosimendan (LLOQ 0.450 nM), OR-1896, and OR-1855 (LLOQ both 1.0 nM) were successfully quantified by LC-ESI-MS/MS after liquid-liquid extraction in 300 µL of blood. A short C8 column under reversed-phase conditions enabled simultaneous and fast quantification of levosimendan in the negative and the metabolites in the positive ionization mode in a single run within 2 min. Interestingly and unexpectedly, constitutional isomers of levosimendan metabolites with identical mass transitions and similar retention times were observed in surgical patients’ samples, which we identified as the metamizole metabolites 4-aminoantipyrine and 4-acetamidoantipyrine. A longer C8 column and a modified mobile phase enabled selective quantification of all analytes in a single run within 7 min. We developed, validated, and applied highly sensitive LC-ESI-MS/MS methods for simultaneous quantification of levosimendan and its metabolites, enabling efficient TDM of cardiac surgery patients even with additional metamizole administration.

Analgesic benefit of metamizole and ibuprofen vs. either medication alone: a randomized clinical trial

BACKGROUND

Postoperative pain relief remains a key problem after surgery. Multimodal pain therapy has proven beneficial in alleviating pain to a certain extent. However, when combining non-opioids, the focus has been on NSAIDs and paracetamol, but effects of combined use are only moderate. Metamizole could be a potent adjunct, due to its preclusion in several countries, data on its combined use are sparse, despite its common use in many countries. The aim of this study was to examine whether the combination of metamizole and ibuprofen is superior in relieving postoperative pain to either drug alone.

METHODS

For this randomized, placebo-controlled, cross-over study, 35 patients undergoing bilateral lower third molar extraction were randomized. Each patient received three applications of 1000mg metamizole + 400mg ibuprofen for surgery on one side and either 1000mg metamizole + placebo or 400mg ibuprofen + placebo on the other side. Pain ratings, rescue-medication (tramadol), and sleep were assessed for 18 hours.

RESULTS

The combined treatment of metamizole and ibuprofen showed lower mean pain scores over 12 hours than ibuprofen (2.4±1.3 vs 3.8±1.6; P=0.005)). Further, combined treatment showed lower mean pain scores over 6 hours than ibuprofen (2.0±1.2 vs. 3.1±1.6; P=0.022) or metamizole alone (2.0±1.2 vs. 3.3±1.7; P=0.015). Consumption of rescue medication was lowest in the combination-group (25% vs. 46%-metamizole; 50%-ibuprofen). The trial was stopped prematurely as the COVID-pandemic halted elective surgeries.

CONCLUSIONS

Combined use enables superior pain control compared to ibuprofen after molar extraction and tends to be superior to metamizole alone. The premature study-termination may overestimate this effect.

The antipyretic effectiveness of dipyrone in the intensive care unit: A retrospective cohort study

Introduction

Dipyrone (metamizol) is regularly used in critical care for pain and fever treatment, especially in Germany and Spain. However, indication for antipyretic therapy in critically ill patients is currently unclear and data for both the risk and benefit of dipyrone treatment in the intensive care environment are scarce. We hypothesized that antipyretic efficiency of dipyrone would not exceed antipyretic efficiency of acetaminophen. We therefore aimed to compare temperature courses in critically ill patients receiving either intravenous dipyrone, acetaminophen or no antipyretic medication.

Material and methods

We included 937 intensive care unit (ICU) patients with body temperature recordings of at least 37.5°C. We investigated temperature decrease associated with dipyrone or acetaminophen and additionally compared it to an untreated control group.

Results

Within the eight-hour study interval, maximum body temperature decrease in patients without antipyretic medication was -0.6°C (IQR: -1.0 to -0.4°C; n = 315). Maximal decrease in body temperature was higher both with dipyrone (-0.8°C (IQR: -1.2 to -0.4°C); p = 0.016; n = 341) and acetaminophen (-0.9°C (IQR: -1.6 to -0.6°C); p<0.001; n = 71), but did not differ between dipyrone and acetaminophen (p = 0.066). As compared to untreated patients, dipyrone only led to a marginal additional decrease in body temperature of only -0.1°C. Maximum of antipyretic effectiveness was reached four hours after administration.

Conclusion

Antipyretic effectiveness of dipyrone in ICU patients may be overestimated. Given the lack of prospective data, clinical evidence for antipyretic dipyrone therapy in the ICU is insufficient and warrants further critical evaluation.

Intravenous ibuprofen versus diclofenac plus orphenadrine in orthognathic surgery: a prospective, randomized, double-blind, controlled clinical study

Objectives

The aim of this prospective, randomized, double-blind, controlled clinical study was to evaluate the analgesic effect of ibuprofen versus diclofenac plus orphenadrine on postoperative pain in orthognathic surgery.

Material and methods

Patients who underwent orthognathic surgery were randomized into two groups to receive intravenously either 600 mg of ibuprofen (I-group) or 75 mg diclofenac plus 30 mg orphenadrine (D-group), both of which were given twice daily. Additionally, both groups were given metamizole 500 mg. Rescue pain medication consisted of acetaminophen 1000 mg and piritramide 7.5 mg as needed. To assess the pain intensity, the primary end point was the numeric rating scale (NRS) recorded over the course of the hospital stay three times daily for 3 days.

Results

One hundred nine patients were enrolled (age range, 18 to 61 years) between May 2019 and November 2020. Forty-eight bilateral sagittal split osteotomies (BSSO) and 51 bimaxillary osteotomies (BIMAX) were performed. Surgical subgroup analysis found a significant higher mean NRS (2.73 vs.1.23) in the BIMAX D-group vs. I-group (p = 0.015) on the third postoperative day. Additionally, as the patient’s body mass index (BMI) increased, the mean NRS (r = 0.517, p = 0.001) also increased. No differences were found between age, gender, length of hospital stay, weight, operating times, number of patients with complete pain relief, acetaminophen or piritramide intake, and NRS values. No adverse events were observed.

Conclusion

The results of this study demonstrate that ibuprofen administration and lower BMI were associated with less pain for patients who underwent bimaxillary osteotomy on the third postoperative day. Therefore, surgeons may prefer ibuprofen for more effective pain relief after orthognathic surgery.

Clinical relevance

Ibuprofen differs from diclofenac plus orphenadrine in class and is a powerful analgetic after orthognathic surgery.

Excess Mortality in Aspirin and Dipyrone (Metamizole) Co-Medicated in Patients With Cardiovascular Disease: A Nationwide Study

Background

Pain is a major issue in our aging society. Dipyrone (metamizole) is one of the most frequently used analgesics. Additionally, it has been shown to impair pharmacodynamic response to aspirin as measured by platelet function tests. However, it is not known how this laboratory effect translates to clinical outcome.

Methods and Results

We conducted a nationwide analysis of a health insurance database in Germany comprising 9.2 million patients. All patients with a cardiovascular event in 2014 and subsequent secondary prevention with aspirin were followed up for 36 months. Inverse probability of treatment weighting analysis was conducted to investigate the rate of mortality, myocardial infarction, and stroke/transient ischemic attack between patients on aspirin‐dipyrone co‐medication compared with aspirin‐alone medication. Permanent aspirin‐alone medication was given to 26,200 patients, and 5946 patients received aspirin–dipyrone co‐medication. In the inverse probability of treatment weighted sample, excess mortality in aspirin–dipyrone co‐medicated patients was observed (15.6% in aspirin‐only group versus 24.4% in the co‐medicated group, hazard ratio [HR], 1.66 [95% CI, 1.56–1.76], P<0.0001). Myocardial infarction and stroke/transient ischemic attack were increased as well (myocardial infarction: 1370 [5.2%] versus 355 [5.9%] in aspirin‐only and co‐medicated groups, respectively; HR, 1.18 [95% CI, 1.05–1.32]; P=0.0066, relative risk [RR], 1.14; number needed to harm, 140. Stroke/transient ischemic attack, 1901 [7.3%] versus 506 [8.5%] in aspirin‐only and co‐medicated groups, respectively; HR, 1.22 [95% CI, 1.11–1.35]; P<0.0001, RR, 1.17, number needed to harm, 82).

Conclusions

In this observational, nationwide analysis, aspirin and dipyrone co‐medication was associated with excess mortality. This was in part driven by ischemic events (myocardial infarction and stroke), which occurred more frequently in co‐medicated patients as well. Hence, dipyrone should be used with caution in aspirin‐treated patients for secondary prevention.

Uterotrophic and in vitro screening for (anti)estrogenic activity of dipyrone

Dipyrone is a commonly used analgesic in many countries and there is limited data on its possible endocrine disrupting effects. We performed a screening for in vivo and in vitro anti(estrogenic) activity of dipyrone. For the in vivo uterotrophic assay, immature female rats (22-days-old) were treated daily by oral gavage for three days with different doses of dipyrone alone (50, 100, 200 mg/kg/day) and associated with three ethynylestradiol (EE) doses (1, 3 and 10 μg/kg/day), which were based on a dose-response curve experiment. The uterine weight was used as a biomarker for estrogenicity. In a parallel in vitro approach, we used a yeast-based transcriptional activation reporter gene assay (Yeast Estrogen Screening - YES) for assessment of estrogenic agonistic and antagonistic effects of dipyrone and its main metabolites 4-methylaminoantipyrine (MAA) and 4-aminoantipyrine (AA). In the uterotrophic assay, animals that received EE at 1, 3 and 10 μg/kg/day showed an increase in relative uterine weight compared with vehicle-only rats (canola oil). Dipyrone did not increase uterine weight at any dose tested (50, 100 and 200 mg/kg/day) in relation to vehicle control, indicating absence of estrogenic activity. Furthermore, co-administration of dipyrone (50 and 200 mg/kg/day) and EE (1, 3 or 10 μg/kg/day) was unable to block EE estrogenic action in comparison to the groups treated with EE alone, indicating absence of antiestrogenic activity. In the YES assay dipyrone and its metabolites did not demonstrate estrogen agonistic or antagonistic properties in the yeast cells. These results suggest that dipyrone and its metabolites do not produce (anti)estrogenic effects in vivo or in vitro.

Comparative Effects of Metamizole (Dipyrone) and Naproxen on Renal Function and Prostacyclin Synthesis in Salt-Depleted Healthy Subjects - A Randomized Controlled Parallel Group Study

Aim: The objective was to investigate the effect of metamizole on renal function in healthy, salt-depleted volunteers. In addition, the pharmacokinetics of the four major metamizole metabolites were assessed and correlated with the pharmacodynamic effect using urinary excretion of the prostacyclin metabolite 6-keto-prostaglandin F1α. Methods: Fifteen healthy male volunteers were studied in an open-label randomized controlled parallel group study. Eight subjects received oral metamizole 1,000 mg three times daily and seven subjects naproxen 500 mg twice daily for 7 days. All subjects were on a low sodium diet (50 mmol sodium/day) starting 1 week prior to dosing until the end of the study. Glomerular filtration rate was measured using inulin clearance. Urinary excretion of sodium, potassium, creatinine, 6-keto-prostaglandin F1α, and pharmacokinetic parameters of naproxen and metamizole metabolites were assessed after the first and after repeated dosing. Results: In moderately sodium-depleted healthy subjects, single or multiple dose metamizole or naproxen did not significantly affect inulin and creatinine clearance or sodium excretion. Both drugs reduced renal 6-keto-prostaglandin F1α excretion after single and repeated dosing. The effect started 2 h after intake, persisted for the entire dosing period and correlated with the concentration-profile of naproxen and the active metamizole metabolite 4-methylaminoantipyrine (4-MAA). PKPD modelling indicated less potent COX-inhibition by 4-MAA (EC₅₀ 0.69 ± 0.27 µM) compared with naproxen (EC₅₀ 0.034 ± 0.033 µM). Conclusions: Short term treatment with metamizole or naproxen has no significant effect on renal function in moderately sodium depleted healthy subjects. At clinically relevant doses, 4-MAA and naproxen both inhibit COX-mediated renal prostacyclin synthesis.

Assessment of the cytoprotective effect of the homeopathic compound Canova® on African green monkey kidney (VERO) cell line exposed to the drug dipyrone sodium

Dipyrone or metamizole is one of the most frequently used analgesic worldwide. Despite its widespread use, this drug may exert genotoxic and cytotoxic effects on lymphocytes. Therefore, studies with therapeutic agents that may provide protection against these effects are important. The homeopathic compound Canova® (CA) appears to be a beneficial candidate for preventing DNA damage and cellular lethality, since this compound acts as an immunomodulator associated with cytoprotective actions. Hence, the aim of the present investigation was to determine the potential cytoprotective effects of CA using cell line VERO as a model. VERO cells were incubated with sodium dipyrone and subsequently subject to the comet, apoptosis and immunocytochemistry assays. Data demonstrated that sodium dipyrone induced an increase in DNA damage index (DI) employing the comet assay. However, when VERO cells were co-treated with CA at the three concentrations studied, a significant reduction in DI was observed, indicating an antigenotoxic effect attributed to CA. Further dipyrone induced an elevation in %apoptosis at 24 and 48 hr. However, when dipyrone was co-incubated with CA, a significant reduction in %apoptosis was noted at the three concentrations of CA employed. Results from immunocytochemical analysis showed a rise in the expression of caspase 8 and cytochrome C when cells were exposed to dipyrone. In contrast, co-treatment of dipyrone and CA significantly reduced the effect of dipyrone. Therefore, evidence indicated that CA acted as an anticytotoxic and antigenotoxic agent counteracting damage induced by dipyrone.

Inherent Dangers of Using Non-US Food and Drug Administration-Approved Substances of Abuse

Use of US Food and Drug Administration-approved substances of abuse has innate risks due to pharmacologic and pharmacokinetic properties of the medications, but the risk when using nonapproved drug products is much greater. Unbeknownst to the user, the dose of active ingredients in substances of abuse can vary substantially between different products because of manufacturing practices or improper storage. Even naturally occurring substances of abuse can have extensive dosage variability because of effects of the growing season and conditions, or differences in harvesting, storage, or manufacture of the finished products. Many illicit substances are adulterated, to make up for intentional underdosing or to enhance the effect of the intended active ingredient. These adulterants can be dangerous and produce direct cardiovascular, neurologic, hematologic, or dermatologic reactions or obscure adverse effects. Finally, an illicit substance can be contaminated or substituted for another one during its manufacture, leading to differences in adverse events, adverse event severity, or the drug interaction profile. Substances can be contaminated with microbes that induce infections or heavy metals that can damage organs or cause cancer. This milieu of undisclosed substances can also induce drug interactions. For reasons that are discussed, individuals who use substances of abuse are at increased risk of morbidity or mortality if they develop coronavirus disease 2019. Health professionals who treat patients with acute, urgent events associated with substances of abuse, or those treating the chronic manifestations of addiction, need to appreciate the complex and variable composition of substances of abuse and their potential health effects.

Self-medication with analgesics reported by patients with ulcerative colitis: An anonymous survey

INTRODUCTION

Analgesics are widely used, but evidence regarding whether their use increases the risk of inflammatory bowel disease (IBD) flares or complications is unclear. Therefore, self-medication with analgesics in IBD is usually not recommended. The aim of this study was to explore the prevalence of self-medication with analgesics in a cohort of ulcerative colitis (UC) patients and to identify reasons and factors associated with self-medication.

METHODS

This cross-sectional study included consecutive unselected adult patients with UC. Participants were asked to complete an anonymous web-based survey with multiple-choice questions and closed responses. No clinical data were collected.

RESULTS

A total of 546 patients (61.2% women, mean age 39.9 years) completed the survey. The prevalence of self-medication with analgesics was 49.8% (272/546). Paracetamol (45.2%) and metamizole (21.2%) were the most frequently used drugs; frequencies of self-medication were <5% for other analgesics (nonsteroidal anti-inflammatory drugs, opioids). The most frequent reasons for self-medication were the need for quick symptom relief and that it had been agreed with/prescribed by the treating physician. Multivariable analysis identified female sex (odds ratio [OR]=1.9), sick leave (OR=2.2), treatment with intravenous drugs (OR=2.9), and emergency room visit (OR=2.3) as variables associated with self-medication, whilst follow-up by a nurse was associated with less self-medication (OR=0.6).

CONCLUSION

The frequency of self-medication with analgesics in UC patients is high and appears to be associated with variables suggesting worse disease control. Closer follow-up, including a specialized nurse, could decrease self-medication. Strategies to improve disease control, including close monitoring of symptoms such as pain, are needed.

[Perioperative analgesia with nonopioid analgesics : Joint interdisciplinary consensus-based recommendations of the German Pain Society, the German Society of Anaesthesiology and Intensive Care Medicine and the German Society of Surgery]

BACKGROUND

Nonopioid analgesics are frequently used for perioperative analgesia; however, insufficient research is available on several practical issues. Often hospitals have no strategy for how to proceed, e.g., for informing patients or for the timing of perioperative administration of nonopioid analgesics.

METHODS

An expert panel representing the German national societies of pain, anaesthesiology and intensive care medicine and surgery developed recommendations for the perioperative use of nonopioid analgesics within a formal, structured consensus process.

RESULTS

The panel agreed that nonopioid analgesics shall be part of a multimodal analgesia concept and that patients have to be informed preoperatively about possible complications and alternative treatment options. Patients' history of pain and analgesic intake shall be evaluated. Patients at risk of severe postoperative pain and possible chronification of postsurgical pain shall be identified. Depending on the duration of surgery, nonopioid analgesics can already be administered preoperatively or intraoperatively so that plasma concentrations are sufficient after emergence from anesthesia. Nonopioid analgesics or combinations of analgesics shall be administered for a limited time only. An interdisciplinary written standard of care, comprising the nonopioid analgesic of choice, possible alternatives, adequate dosing and timing of administration as well as surgery-specific policies, have to be agreed upon by all departments involved. At discharge, the patient's physician shall be informed of analgesics given and those necessary after discharge. Patients shall be informed of possible side effects and symptoms and timely discontinuation of analgesic drugs.

CONCLUSION

The use of nonopioid analgesics as part of a perioperative multimodal concept should be approved and established as an interdisciplinary and interprofessional concept for the adequate treatment of postoperative pain.

[Perioperative analgesia with nonopioid analgesics : Joint interdisciplinary consensus-based recommendations of the German Pain Society, the German Society of Anaesthesiology and Intensive Care Medicine and the German Society of Surgery]

BACKGROUND

Nonopioid analgesics are frequently used for perioperative analgesia; however, insufficient research is available on several practical issues. Often hospitals have no strategy for how to proceed, e.g., for informing patients or for the timing of perioperative administration of nonopioid analgesics.

METHODS

An expert panel representing the German national societies of pain, anaesthesiology and intensive care medicine and surgery developed recommendations for the perioperative use of nonopioid analgesics within a formal, structured consensus process.

RESULTS

The panel agreed that nonopioid analgesics shall be part of a multimodal analgesia concept and that patients have to be informed preoperatively about possible complications and alternative treatment options. Patients' history of pain and analgesic intake shall be evaluated. Patients at risk of severe postoperative pain and possible chronification of postsurgical pain shall be identified. Depending on the duration of surgery, nonopioid analgesics can already be administered preoperatively or intraoperatively so that plasma concentrations are sufficient after emergence from anesthesia. Nonopioid analgesics or combinations of analgesics shall be administered for a limited time only. An interdisciplinary written standard of care, comprising the nonopioid analgesic of choice, possible alternatives, adequate dosing and timing of administration as well as surgery-specific policies, have to be agreed upon by all departments involved. At discharge, the patient's physician shall be informed of analgesics given and those necessary after discharge. Patients shall be informed of possible side effects and symptoms and timely discontinuation of analgesic drugs.

CONCLUSION

The use of nonopioid analgesics as part of a perioperative multimodal concept should be approved and established as an interdisciplinary and interprofessional concept for the adequate treatment of postoperative pain.

Is otologic surgery contributing to the opioid epidemic?

Background

The opioid epidemic is a significant public health crisis challenging the lives of North Americans. Interestingly, this problem does not exist to the same extent in Europe. Surgeons play a significant role in prescribing opioids, especially in the context of post-operative pain management. The aim of this study was to compare the post-surgical prescribing patterns of otologists comparing Canada and Austria.

Methods

An online questionnaire was sent to 33 Canadian and 32 Austrian surgeons, who perform otologic surgery on a regular basis. Surgeons were asked to answer some questions about their background as well as typical prescribing patterns for postoperative pain medication for different ear surgeries (cochlear implant, stapedotomy, tympanoplasty). In addition, surgeons were asked about the typical use of local anesthetics for pain control at the end of a procedure. Otologists gave an estimate how confident they were that their therapy and prescriptions provide sufficient pain control to their patients.

Results

Analysis of the returned questionnaires showed that opioids are more commonly prescribed in Canada than in Austria. Nonsteroidal anti-inflammatory drugs are used for postoperative pain more regularly after ear surgery in Austria, as opposed to Canada. Some of the prescribed drugs by European otologists are not available in North America. The use of local anesthetics at the end of surgery is not common in Austria. Surgeons´ confidence that the prescribed pain medication was sufficient to control postoperative symptoms was higher in the group not prescribing opioids than in the group that did routinely prescribe opioids.

Conclusion

Prescribing patterns differ substantially between the two evaluated countries. This data suggests an opportunity to reduce opioid prescriptions after otologic surgeries. Studies to evaluate pain after these operations as well as efficacy of analgesics following ear surgery are an important next step.

Graphical abstract

[Perioperative analgesia with nonopioid analgesics : Joint interdisciplinary consensus-based recommendations of the German Pain Society, the German Society of Anaesthesiology and Intensive Care Medicine and the German Society of Surgery]

Hintergrund

Nichtopioidanalgetika werden bei vielen Patienten zur perioperativen Analgesie eingesetzt. Zu einigen praktischen Fragen beim Einsatz von Nichtopioidanalgetika liegen z. T. nur wenig Informationen aus Studien vor, und in Krankenhäusern existieren häufig keine Konzepte zum Vorgehen, z. B. zur Patientenaufklärung und zum Zeitpunkt der perioperativen Gabe.

Methodik

Eine Expertengruppe der beteiligten Fachgesellschaften hat konsensbasierte Empfehlungen zum perioperativen Einsatz von Nichtopioidanalgetika erarbeitet und in einem strukturierten formalen Konsensusprozess verabschiedet.

Ergebnisse

Die Arbeitsgruppe stimmt überein, dass Nichtopioidanalgetika Bestandteil eines perioperativen multimodalen Analgesiekonzepts sein sollen und Patienten präoperativ über Nutzen, Risiken und alternative Behandlungsmöglichkeiten aufgeklärt werden sollen. Die präoperative Patienteninformation und -edukation soll auch eine Schmerz- und Analgetikaanamnese umfassen und Patienten mit Risikofaktoren für starke Schmerzen und eine Schmerzchronifizierung sollen identifiziert werden. Unter Berücksichtigung von Kontraindikationen können Nichtopioidanalgetika abhängig von der Operationsdauer auch schon prä- oder intraoperativ gegeben werden, um nach Beendigung der Anästhesie ausreichende Plasmakonzentrationen zu erzielen. Nichtopioidanalgetika oder Kombinationen von (Nichtopioid‑)Analgetika sollen nur für einen begrenzten Zeitraum gegeben werden. Ein gemeinsam erarbeiteter abteilungsübergreifender Behandlungsstandard mit dem Nichtopioidanalgetikum erster Wahl, weiteren Therapieoptionen sowie adäquaten Dosierungen, ergänzt durch eingriffsspezifische Konzepte, soll schriftlich hinterlegt werden. Bei Entlassung aus dem Krankenhaus soll der nachbehandelnde Arzt zu perioperativ gegebenen und aktuell noch eingenommenen Analgetika schriftliche Informationen erhalten. Patienten sollen zu möglichen Nebenwirkungen der Analgetika und ihrer Symptome, die auch nach Krankenhausentlassung auftreten können, und die befristete Einnahmedauer informiert werden.

Schlussfolgerung

Die Anwendung von Nichtopioidanalgetika soll als Bestandteil eines perioperativen multimodalen Analgesiekonzepts mit klaren Vorgaben zu Indikationen, Kontraindikationen, Dosierungen und Behandlungsdauer in einem abteilungsübergreifenden Behandlungsstandard schriftlich hinterlegt werden.

Zusatzmaterial online

Die Offenlegung von Interessen ist in der Online-Version dieses Artikels (10.1007/s00104-021-01421-w) enthalten.

Preventive Analgesia, Hemodynamic Stability, and Pain in Vitreoretinal Surgery

Background and Objectives: Although vitreoretinal surgery (VRS) is most commonly performed under regional anaesthesia (RA), in patients who might be unable to cooperate during prolonged procedures, general anaesthesia (GA) with intraprocedural use of opioid analgesics (OA) might be worth considering. It seems that the surgical pleth index (SPI) can be used to optimise the intraprocedural titration of OA, which improves haemodynamic stability. Preventive analgesia (PA) is combined with GA to minimise intraprocedural OA administration. Materials and Methods: We evaluated the benefit of PA combined with GA using SPI-guided fentanyl (FNT) administration on the incidences of PIPP (postprocedural intolerable pain perception) and haemodynamic instability in patients undergoing VRS (p < 0.05). We randomly assigned 176 patients undergoing VRS to receive GA with SPI-guided FNT administration alone (GA group) or with preventive topical 2% proparacaine (topical anaesthesia (TA) group), a preprocedural peribulbar block (PBB) using 0.5% bupivacaine with 2% lidocaine (PBB group), or a preprocedural intravenous infusion of 1.0 g of metamizole (M group) or 1.0 g of paracetamol (P group). Results: Preventive PBB reduced the intraprocedural FNT requirement without influencing periprocedural outcomes (p < 0.05). Intraprocedural SPI-guided FNT administration during GA resulted in PIPP in 13.5% of patients undergoing VRS and blunted the periprocedural effects of preventive intravenous and regional analgesia with respect to PIPP and haemodynamic instability. Conclusions: SPI-guided FNT administration during GA eliminated the benefits of preventive analgesia in the PBB, TA, M, and P groups following VRS.

Liver Injury Associated with Metamizole Exposure: Features of an Underestimated Adverse Event

INTRODUCTION AND OBJECTIVE

The potential of metamizole to cause drug-induced liver injury (DILI) has received increasing attention. We investigated the distinguishing features of a case series comprising 32 patients with suspected metamizole-induced DILI.

METHODS

For the current analysis, 32 of 238 patients with DILI included in our prospective study on drugs potentially causing DILI were included. Diagnosis of DILI was based on expert opinion and RUCAM (Roussel Uclaf Causality Assessment Method) score and supported by an in vitro test using monocyte-derived hepatocyte-like cells.

RESULTS

Suspected metamizole-DILI was characterised by a female predominance, hepatocellular pattern of injury, high proportion of antinuclear antibody positivity, and predominance of eosinophilic cell infiltration and necrosis in the histopathological analysis. With 22%, a high proportion of these metamizole-associated liver injury cases developed acute liver failure, which was characterised by a longer latency of metamizole use and more pronounced liver biochemistry abnormalities at onset and peak levels. Furthermore, jaundice was a common finding in the metamizole-associated liver injury cases with 66% presenting with peak bilirubin levels of 3 mg/dL or higher, which was associated with a worse outcome and a higher frequency of acute liver failure.

CONCLUSIONS

Our analysis of a well-characterised DILI cohort further supports the potential of metamizole causing DILI and provides important features for the establishment of a signature pattern of liver injury observed in patients treated with metamizole.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02353455.

[Analgesia for trauma patients in emergency medicine]

Adequate analgesia is one of the most important measures of emergency care in addition to treatment of vital function disorders and, if indicated, should be promptly undertaken; however, a large proportion of emergency patients receive no or only inadequate pain therapy. The numeric rating scale (NRS) is recommended for pain assessment but is not applicable to every group of patients; therefore, vital signs and body language should be included in the assessment. Pain therapy should reduce the NPRS to <5 points. Ketamine and fentanyl, which have an especially rapid onset of action, and also morphine are suitable for analgesia in spontaneously breathing patients. Basic prerequisites for safe and effective analgesia by healthcare professionals are the use of adequate monitoring, the provision of well-defined emergency equipment, and the mastery of emergency procedures. In a structured competence system, paramedics and nursing personnel can perform safe and effective analgesia.

[Updating in prescription of proton pump inhibitors. What to do and what not to do]

INTRODUCTION

Proton pump inhibitors (PPIs) are the most prescribed pharmacological subgroup of the National Health System and their use has been related to possible potentially serious adverse effects.

OBJECTIVE

To review the current indications for treatment with PPIs as well as the data related to their safety, in order to promote their adecuate use.

MATERIAL AND METHODS

A review of the literature focused on the following topics has been carried out: a) molecules and mechanism of action; b) current indications for treatment and adherence to them; c) adverse effects related to its use; d) drug interactions; e) alternatives in deprescription.

RESULTS

The current indications have not changed substantially in recent years and are well established, however, there is a high percentage of inappropriate prescription, mainly in individuals with low or no risk.

CONCLUSIONS

PPIs are safe drugs and generally well tolerated and their benefits are higher than possible adverse effects. Adhering to evidence-based recommendations represents the only rational approach to safe and effective therapy.

Cyclooxygenases 1 and 2 inhibition and analgesic efficacy of dipyrone at different doses or meloxicam in cats after ovariohysterectomy

OBJECTIVE

To evaluate the cyclooxygenases (COX) inhibition, adverse effects and analgesic efficacy of dipyrone or meloxicam in cats undergoing elective ovariohysterectomy.

STUDY DESIGN

Prospective, blinded, randomized, clinical study.

ANIMALS

A total of 30 healthy young cats.

METHODS

The cats were randomly assigned to three postoperative groups: D25 (dipyrone 25 mg kg^-1 every 24 hours), D12.5 (dipyrone 12.5 mg kg^-1 every 12 hours) and M (meloxicam 0.1 mg kg^-1 every 24 hours). In the first 24 hours, the drugs were administered intravenously (IV), and then orally for 6 (dipyrone) or 3 days (meloxicam). Prostanoids thromboxane B₂ and prostaglandin E₂ concentrations served as indicators of COX activity and, with physiological variables and pain and sedation scores, were measured for 24 hours after first analgesic administration. Rescue analgesia (tramadol, 2 mg kg^-1 IV) was provided if Glasgow feline composite measure pain scale (CMPS-Feline) ≥5. Laboratory tests included symmetric dimethylarginine and adverse effects were evaluated regularly up to 7 and 10 days after surgery, respectively. Parametric and nonparametric data were analyzed with two-way anova and Kruskal-Wallis tests, respectively (p < 0.05).

RESULTS

In the first half hour after analgesic administration, COX-1 activity was close to zero and remained significantly lower than before drug administration for 24 hours in all groups. The inhibition of COX-2 activity was significant for 30 minutes in all groups and up to 4 hours in group M. No alterations in laboratory tests or significant adverse effects were observed. Pain scores and need for rescue analgesia did not differ statistically among groups.

CONCLUSIONS

Dipyrone at both doses and meloxicam provided a nonselective inhibition of COX-1 and -2 activities and effective analgesia without causing significant adverse effects or laboratory tests alterations.

CLINICAL RELEVANCE

Dipyrone at both doses provides equally effective analgesia without causing adverse effects in cats undergoing ovariohysterectomy.

[Considerations concerning the perioperative use of metamizole]

BACKGROUND

The non-opioid analgesic metamizole (dipyrone) is approved for the treatment of severe pain and is often used in the perioperative period. As it can cause agranulocytosis, a severe adverse event, its perioperative administration is controversially discussed.

OBJECTIVE

Is there enough evidence for a high risk of metamizol-induced agranulocytosis (MIA)? What are the consequences of its perioperative use with respect to the risk profiles of alternative analgesics?

MATERIAL AND METHODS

Rapid review of the literature on the risk of MIA and adverse effects of non-opioid analgesics.

RESULTS

The incidence of MIA is estimated to be one case per million inhabitants per year. The risk seems low compared to other drugs associated with a risk of agranulocytosis, such as antithyroid drugs and ticlopidine. The risk profile of metamizole concerning hepatotoxicity, nephrotoxicity, bleeding and cardiovascular adverse effects is favorable compared to other non-opioid analgesics. None of the non-opioid analgesics are licensed to be administered intraoperatively.

CONCLUSION

The perioperative use of metamizole is possible after a thorough evaluation of the indications as it provides good analgesia with a generally favorable side effect profile and is administered intravenously. The risk of agranulocytosis is small but needs to be mentioned during patient informed consent in order to optimize early recognition. Intraoperative administration aims at reducing the expected severe postoperative pain. A documentation and justification for the evaluation of the indications are recommended.

[Recommendations for the perioperative use of dipyrone : Expert recommendation of the working group on acute pain of the German Pain Society, the scientific working group on pain medicine of the German Society for Anesthesiology and Intensive Care Medicine and the surgical working group on acute pain of the German Society for Surgery with participation of representatives of the Drug Commission of the German Medical Association]

BACKGROUND

Dipyrone (metamizole) is widely used for perioperative pain management in countries where it is marketed; however, uncertainty exists concerning the safe use of this drug, specifically considering the rare adverse event of an agranulocytosis.

METHODS

As evidence from published studies was lacking, an expert panel developed recommendations for the perioperative use of dipyrone. After a formal, structured consensus process, the recommendations were approved by the involved medical societies.

RESULTS

The panel agreed that blood cell counts shall not be standard for short-term perioperative use in patients unless they are at risk for neutropenia. The medical staff shall be aware of the symptoms and course of action when agranulocytosis is suspected. Patients shall be informed about the risks and benefits of dipyrone and about potential alternatives. The expert group concluded that dipyrone has a relatively positive risk-benefit ratio compared to other nonopioid analgesics. The group strongly recommended educating patients about the symptoms of agranulocytosis if they have received dipyrone over several days and/or treatment is to be continued after discharge, because agranulocytosis can occur several days after discontinuation of metamizole. Further recommendations refer to the information of the physician taking over the patient's care after discharge and the avoidance of re-exposure in patients having previously suffered from dipyrone-induced agranulocytosis.

CONCLUSION

The group's recommendations shall be communicated in order to raise medical staff's and patients' awareness of the appropriate use of dipyrone in the perioperative period.

Spezielle Schmerztherapie bei rheumatischen Erkrankungen

Schmerz als Hauptsymptom vieler chronisch-entzündlicher Erkrankungen stellt für den Patienten, aber auch für den behandelnden Arzt besonders in seiner chronifizierten Form eine große Herausforderung dar. Es gibt leider keine „Wunderpille“ mit der man Schmerzen für jeden gleich zuverlässig beseitigen kann. Es gibt aber viele Ansätze pharmakologischer als auch nicht-pharmakologischer Art und deren Kombination, um für den einzelnen Patienten wirksame Behandlungsstrategien zu finden. Um diese Strategien für jeden Patienten individuell optimal festzulegen, bedarf es zum einen eines fundamentierten Wissens über das Spektrum zur Verfügung stehender Mittel, zum anderen aber auch Erkenntnis darüber, wie diese sinnvoll nach Art der vorliegenden Schmerzformen einzusetzen sind. In dieser Übersicht wird beides behandelt, mit einem Fokus auf die medikamentöse Therapie von Schmerzen bei entzündlich-rheumatischen Erkrankungen. Dabei wird herausgearbeitet, dass es für die in diesem Zusammenhang relevantesten Formen des Schmerzes, akut-entzündlich nozizeptiv, neuropathisch und durch periphere und zentrale Sensibilisierung chronifizierte Schmerzen, jeweils andere wirksame Konzepte gibt.

Use of metamizole as an additional analgesic during umbilical surgery in calves

OBJECTIVE

To investigate the effect of metamizole on physiologic variables in calves undergoing surgical extirpation of the navel during anaesthesia using xylazine, ketamine and isoflurane.

STUDY DESIGN

Double-blind, randomized trial.

ANIMALS

A total of 26 calves.

METHODS

Calves with uncomplicated umbilical hernias and otherwise clinically healthy were randomly allocated to one of two groups: the control group (CG) and metamizole group (MG). All calves were administered meloxicam (0.5 mg kg-1) intravenously (IV) 150 minutes before skin incision (SI). Animals were premedicated with xylazine (0.2 mg kg-1) intramuscularly 50 minutes before SI. Anaesthesia was induced with ketamine (2 mg kg-1) IV 30 minutes before SI and maintained with isoflurane in oxygen. MG calves were given metamizole (40 mg kg-1) IV 60 minutes before SI. CG calves were administered an equivalent volume of saline. Heart rate (HR) and mean arterial blood pressure (MAP) were recorded from 5 minutes before SI until the end of anaesthesia (60 minutes after SI). Blood samples for determination of the plasma cortisol concentration (PCC) were drawn 60 minutes before SI and at 5, 30, 60, 150, and 510 minutes after SI.

RESULTS

In both groups, PCC increased during surgery and decreased after surgery. PCC was consistently lower in MG than in CG and was significantly (p = 0.0026) lower at 150 minutes after SI in the MG. Overall, the mean PCC in MG was 10.9 nmol L-1 lower than that in CG (p = 0.01). In both groups, HR decreased during anaesthesia, whereas MAP increased, albeit with no statistically significant (p > 0.05) differences between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Our study results suggest that a single preoperative dose of metamizole may have a positive impact on intra- and immediate postoperative analgesia by reducing PCC when used as an indicator of nociception.

Pain Response to Open Label Placebo in Induced Acute Pain in Healthy Adult Males

Background

Open label placebos with patient education are effective in reducing chronic pain, and recent studies on their effect on pain have established interest in this field. Nevertheless, data on their effect on acute pain are scarce, and on hyperalgesia and allodynia, absent. This study assessed the effect of open label placebos on acute pain in healthy adult males and the influence of placebo education.

Methods

Thirty-two healthy males were included in this prospective, randomized, assessor-blinded crossover, single-center study assessing pain intensities (via numeric rating scale), area of hyperalgesia (von Frey filament), and allodynia (dry cotton swab) in a pain model utilizing intracutaneous electrical stimulation. The authors compared the effect of intravenous open label placebo on pain compared to no treatment. The authors further examined the effect of placebo on hyperalgesia and allodynia, and the influence of education (short vs. detailed) before placebo application. Saliva cortisol concentrations were also measured.

Results

Pain ratings (median, first to third quartile) were 21% lower during placebo treatment compared to no treatment, 4.0 (3.2 to 4.9) versus 5.1 (4.7 to 5.4), respectively (P = 0.001). The areas of hyperalgesia and allodynia were lower during placebo treatment compared to no treatment (hyperalgesia, 30 cm2 [17 to 47] vs. 55 cm2 [42 to 68], P = 0.003; allodynia, 24 cm2 [11 to 39] vs. 45 cm2 [31 to 62], P = 0.007). This corresponds to reductions of 47%. The extent of placebo education had no effect on pain. Saliva cortisol decreased significantly over time and was under the limit of detectability in the majority of participants in postbaseline measurements in both treatment branches. Baseline cortisol was not associated with the placebo effect or strength applied of current to reach defined pain ratings.

Conclusions

Open label placebos might play a role in multimodal analgesic concepts.

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Development and validation of an LC–MS/MS method for the bioanalysis of the major metamizole metabolites in human plasma

Aim: Metamizole is a frequently used antipyretic and analgesic prodrug, yet its pharmacokinetics has not been thoroughly studied in infants and with coadministered medications. Thus, an LC–MS/MS method was developed to quantify the four major metamizole metabolites in human plasma. Methodology: Pre- and postcolumn infusion was installed to enable robust analyte retention and electrospray ionization following deproteinization of plasma samples. Results: The method was linear (R > 0.996), accurate (93.1–106.0%) and precise (≤12.7%). Mean recovery was more than 91.8% and ion suppression less than 13.1% for all analytes. Pharmacokinetic profiles were reproducible after 4 years at -80°C except for the formylated metabolite (-22.2%). Conclusion: The method fulfilled pertinent criteria of validation guidelines and required only little sample volume. The method therefore qualifies for metamizole analyses in children.

Metamizole and the risk of drug-induced agranulocytosis and neutropenia in statutory health insurance data

The non-opioid analgesic metamizole (dipyrone) is used for the treatment of acute and chronic pain and fever. Agranulocytosis is known as a serious adverse drug reaction of metamizole with potentially fatal outcome. However, its frequency is controversially discussed. The aim of our study was to determine the risk of metamizole-associated agranulocytosis and neutropenia using statutory health insurance data. We analyzed data from a large German health insurance fund in the period from 2010 to 2013. Metamizole-exposed subjects were identified and compared to a propensity score-matched control cohort. A total of 630,285 metamizole-treated subjects and 390,830 matched control subjects were included. In the metamizole cohort, ICD codes for agranulocytosis and neutropenia appeared more often than in non-users. The relative risk for drug-induced agranulocytosis and neutropenia (D70.1) was 3.03 (95% confidence interval, 2.49 to 3.69). The risk for developing drug-induced agranulocytosis and neutropenia after metamizole prescription was 1: 1602 (CI 95%, 1:1926 to 1:1371). Our results confirm the risk estimation of previous studies. However, the outcome of our study may be confounded by an association of metamizole treatment and chemotherapy. Therefore, consequences for treatment have to be drawn with care.

Pain and Inflammation Management in Older Adults: A Brazilian Consensus of Potentially Inappropriate Medication and Their Alternative Therapies

Purpose: The aim of the present study was to develop and validate a Potentially Inappropriate Medications (PIM) list and alternative therapies for treatment of pain and inflammation in older people adapted to the Brazilian context.

Methods: A preliminary PIM list suitable for the Brazilian market was developed on the basis of three published international PIM lists [Beers 2015, Screening Tool of Older People’s Potentially Inappropriate Prescriptions - 2015, European Union (7) PIM list]. We used the modified Delphi technique (two-round) to validate concerns of use and alternative therapies related to PIM for treatment of pain and inflammation in older adults ≥65 years in Brazil. The panel involved nine Brazilian experts in geriatric pharmacotherapy. All items with mean Likert scale score ≥4.0 (agree) and the lower limit of 95% confidence interval ≥4.0 were considered validated in this study.

Results: At the end of the consensus process, 94 (65.3%) items of 144 were validated. In total, consensus was reached for 33/35 (94.3%) concerns about drugs that should be avoided in older patients regardless of diagnosis, for 22/23 (95.7%) concerns about drugs that should be avoided in older patients with specific conditions or diseases, for 11/23 (47.8%) with special considerations of use, and for 28/63 (44.4%) of therapeutic alternatives.

Conclusion: Although these criteria are not designed to replace clinical judgement, PIM and alternative therapies lists can be useful to inform prescribers, pharmacists, and health care planners and may serve as a starting point for safe and effective use of medications in older people.

[Recommendations for the perioperative use of dipyrone : Expert recommendation of the working group on acute pain of the German Pain Society, the scientific working group on pain medicine of the German Society for Anesthesiology and Intensive Care Medicine and the surgical working group on acute pain of the German Society for Surgery with participation of representatives of the Drug Commission of the German Medical Association]

BACKGROUND

Dipyrone (metamizole) is widely used for perioperative pain management in countries where it is marketed; however, uncertainty exists concerning the safe use of this drug, specifically considering the rare adverse event of an agranulocytosis.

METHODS

As evidence from published studies was lacking, an expert panel developed recommendations for the perioperative use of dipyrone. After a formal, structured consensus process, the recommendations were approved by the involved medical societies.

RESULTS

The panel agreed that blood cell counts shall not be standard for short-term perioperative use in patients unless they are at risk for neutropenia. The medical staff shall be aware of the symptoms and course of action when agranulocytosis is suspected. Patients shall be informed about the risks and benefits of dipyrone and about potential alternatives. The expert group concluded that dipyrone has a relatively positive risk-benefit ratio compared to other nonopioid analgesics. The group strongly recommended educating patients about the symptoms of agranulocytosis if they have received dipyrone over several days and/or treatment is to be continued after discharge, because agranulocytosis can occur several days after discontinuation of metamizole. Further recommendations refer to the information of the physician taking over the patient's care after discharge and the avoidance of re-exposure in patients having previously suffered from dipyrone-induced agranulocytosis.

CONCLUSION

The group's recommendations shall be communicated in order to raise medical staff's and patients' awareness of the appropriate use of dipyrone in the perioperative period.

Metamizole-associated neutropenia: Comparison of patients with neutropenia and metamizole-tolerant patients

Reports of metamizole-induced neutropenia have increased in Switzerland and Germany over the last decades, most likely reflecting increased use of metamizole. To date, there are no effective strategies to identify patients at increased risk of metamizole-induced neutropenia. In this observational, multi-center comparative study, characteristics of patients with metamizole-associated neutropenia were compared with patients treated with metamizole without developing adverse hematological reactions. Patients with metamizole-induced neutropenia treated at the University Hospitals Basel and Bern between 2005 and 2017 were included. Tolerant comparison patients with continuous metamizole treatment (≥500 mg/day for at least 28 days) were recruited from GP offices and community pharmacies. Forty-eight patients with metamizole-induced neutropenia, consisting of 23 and 25 cases with inpatient-acquired and outpatient-acquired neutropenia, respectively, were compared to 39 metamizole tolerant comparison patients. Median latency until first diagnosis of neutropenia was 6 days (1-61 days) in inpatient cases and 19 days (2-204 days) in outpatient cases. There was no association between non-myelotoxic and non-immunosuppressive co-medication (p = .6627), history of drug allergy (p = .1304), and preexisting auto-immune diseases (p = .2313) and the development of metamizole-induced neutropenia. Our results suggest that autoimmune diseases, history of drug allergy, and concomitant treatment with non-myelotoxic and non-immunosuppressive drugs are likely not individual risk factors for metamizole-associated neutropenia.