Safety of metamizole (dipyrone) for the treatment of mild to moderate pain-an overview of systematic reviews

Metamizole, as known as dipyrone or novaminsulfone is widely used, especially in Latin America, for its analgesic and antipyretic function. However, several countries have banned it due to the risk of agranulocytosis, skin necrosis, and other serious adverse effects. To assess the safety of metamizole compared to other commonly used non-opioid analgesics (paracetamol, ibuprofen, and acetylsalicylic acid). An overview of systematic reviews. The searches were performed in the PubMed, Cochrane Library, Embase, Scopus and LILACS databases. Systematic reviews of randomized and nonrandomized clinical trials with adult patients with mild to moderate pain that assessed the adverse effects of metamizole were included. A methodological quality assessment was performed through ROBIS. The protocol of this systematic review was submitted to the International Prospective Register of Systematic Reviews (Prospero, CRD42021295272). Of 387 identified studies, four were included, with a total of 20,643 participants, all submitted to a single dose by oral, intramuscular, or intravenous route. No study reported a serious adverse effect. However, 60 of 778 patients (7.7%) who used metamizole; 120/828 (14.5%) who used acetylsalicylic acid; 56/443 (12.6%) who used paracetamol; and 27/213 (12.7%) who used ibuprofen had mild adverse effects. A complementary statistical analysis showed that metamizole, at any dose, has a 38.8% lower chance of adverse effects compared to paracetamol and 46.8% compared to acetylsalicylic acid. The results shows that metamizole is a safe drug with evidence of a lower incidence of adverse effects compared to paracetamol and acetylsalicylic acid.

Management of analgesia in acute pancreatitis: Results of a national survey

INTRODUCTION

Acute pancreatitis is one of the main reasons for digestive admissions. Adequate pain treatment is crucial in its management. However, there are hardly any descriptions of the analgesic guidelines used in our setting.

METHODS

On-line survey on analgesic management in acute pancreatitis, aimed at attending physicians and residents practising in Spain.

RESULTS

Two hundred and nine physicians from 88 centres responded to the survey. Ninety percent were specialists in gastrointestinal medicine and 69% worked in a tertiary centre. The majority (64.4%) do not routinely use scales to measure pain. When choosing a drug, experience in its use was the most important factor. The most commonly prescribed initial treatments are: combination of paracetamol and metamizole (53.5%), paracetamol alone (19.1%) and metamizole alone (17.4%). As rescue: meperidine (54.8%), tramadol (17.8%), morphine chloride (17.8%) and metamizole (11.5%). Continuous perfusion is used in 8.2% of initial treatments. Physicians with >10 years of service use more metamizole as monotherapy (50%), while residents and attending physicians with <10 years of service prescribe it in combination with paracetamol (85%). If progression is needed, morphine chloride and meperidine are mainly used. The speciality of the respondent, the size of the work centre and the unit/service where the patients were admitted did not influence the analgesia prescribed. Satisfaction with pain management reached 7.8/10 (SD 0.98).

CONCLUSION

In our setting, metamizole and paracetamol are the most commonly used analgesics as initial pain treatment in acute pancreatitis, and meperidine is the most commonly used rescue analgesic.

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.

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.

Anesthesia and breastfeeding

The importance of breastfeeding with its positive impact on the wellbeing of the mother-infant pair is well established. Anesthesiologists should encourage the promotion of lactation by being willing to give reassurance during the preoperative period and preparing a plan that does not interfere with safe breastfeeding. There is concern regarding the transfer of drugs into breast milk, which may lead to inconsistent advice from many health professionals and to early discontinuation. However, evidence shows that most anesthetic drugs are safe in terms of transfer into breast milk, and hence, compatible with breastfeeding, which should be resumed after anesthesia as soon as the mother is alert and feels well enough to hold her infant, without the need to “pump and dump”. This review provides pharmacokinetic information on commonly used anesthesia drugs and their passage into breast milk, to help practitioners discuss risks and benefits with the mother, emphasizing that anesthesia should not interfere with the benefits of breastfeeding. Four practical clinical scenarios are presented: pregnant women concerned about the effect of epidural analgesia on subsequent breastfeeding, spinal anesthesia for c-section and lactation, patients who will receive general anesthesia during cesarean section, and finally women who are breastfeeding and require anesthesia for elective or urgent surgery. Neuraxial anesthesia allows for better pain control and immediate skin-to-skin contact at the time of childbirth. Also, it interferes the least with the woman’s ability to care for her infant. Regional techniques, opioid-sparing techniques and outpatient surgery are preferred. Drugs such as opioids and longer-acting benzodiazepines should be administered cautiously, particularly in repeat doses.

Drug-Induced Idiosyncratic Agranulocytosis - Infrequent but Dangerous

Drug-induced agranulocytosis is a life-threatening side effect that usually manifests as a severe form of neutropenia associated with fever or signs of sepsis. It can occur as a problem in the context of therapy with a wide variety of drug classes. Numerous drugs are capable of triggering the rare idiosyncratic form of agranulocytosis, which, unlike agranulocytosis induced by cytotoxic drugs in cancer chemotherapy, is characterised by “bizzare” type B or hypersensitivity reactions, poor predictability and a mainly low incidence. The idiosyncratic reactions are thought to be initiated by chemically reactive drugs or reactive metabolites that react with proteins and may subsequently elicit an immune response, particularly directed against neutrophils and their precursors. Cells or organs that exhibit specific metabolic and biotransformation activity are therefore frequently affected. In this review, we provide an update on the understanding of drug-induced idiosyncratic agranulocytosis. Using important triggering drugs as examples, we will summarise and discuss the chemical, the biotransformation-related, the mechanistic and the therapeutic basis of this clinically relevant and undesirable side effect.

[Adequacy of the safety of metamizole and agranulocytosis]

Objetivo

Analizar si la nota informativa de la Agencia Española de Medicamentos y Productos Sanitarios (AEMPS), de 30 de octubre del 2018, sobre agranulocitosis y metamizol contiene la información precisa y necesaria para proteger a los pacientes de la aparición de esta reacción adversa (RA) y si la documentación oficial de los medicamentos con metamizol para médicos, farmacéuticos y población general está adaptada a las directrices de la AEMPS para disminuir el riesgo.

Emplazamiento y participantes

Nota informativa, búsqueda bibliográfica, información sobre los medicamentos con metamizol comercializados en España en la Agencia Europea del Medicamento, fichas técnicas, prospectos, base de datos de información sanitaria Bot PLUS y Catálogo de Especialidades Farmacéuticas. Notificación de 4 casos de agranulocitosis por metamizol posteriores a la fecha de la nota informativa.

Intervenciones y mediciones principales

Comparación de los puntos clave de la nota informativa y de los documentos oficiales sobre metamizol con la bibliografía. Descripción de 4 casos de agranulocitosis por metamizol y aplicación del algoritmo de causalidad y gravedad.

Resultados

La nota informativa presenta ausencias y dudas respecto a la bibliografía y al uso de metamizol en la práctica asistencial. Los documentos oficiales presentan faltas de actualización, indicaciones no aprobadas y dosis superiores a las recomendadas. La nota informativa no ha frenado la presentación de casos de agranulocitosis por metamizol.

Conclusiones

La nota informativa de la AEMPS es mejorable y es necesario actualizar los documentos oficiales de información sobre el metamizol para profesionales sanitarios y pacientes para disminuir el riesgo de agranulocitosis.

A survey of anaesthesia practices at all hospitals performing caesarean sections in Sierra Leone

BACKGROUND

Providing safe anaesthesia is essential when performing caesarean sections, one of the most commonly performed types of surgery. Anaesthesia-related causes of maternal mortality are generally considered preventable. The primary aim of our study was to assess the type of anaesthesia used for caesarean sections in Sierra Leone. Secondary aims were to identify the type and training of anaesthesia providers, availability of equipment and drugs and use of perioperative routines.

METHODS

All hospitals in Sierra Leone performing caesarean sections were included. In each facility, one randomly selected anaesthesia provider was interviewed face-to-face using a predefined questionnaire.

RESULTS

In 2016, 36 hospitals performed caesarean sections in Sierra Leone. The most commonly used anaesthesia method for caesarean section was spinal anaesthesia (63%), followed by intravenous ketamine without intubation; however, there was a wide variety between hospitals. Of all anaesthesia providers, 33% were not qualified to provide anaesthesia independently, as stipulated by local regulations. Of those, 50% expressed high confidence in their skills to handle obstetric emergencies. There were discrepancies among hospitals in the availability of essential drugs, the use of post-operative recovery and the presence of a functioning blood bank.

CONCLUSION

Anaesthesia for caesarean sections in Sierra Leone showed a predominance for spinal anaesthesia. The workforce consisted mainly of non-physicians, of which a third was not trained to provide anaesthesia independently. Both the type of anaesthesia and the presence of qualified anaesthetic providers was widely variable between hospitals. Significant gaps were identified in the availability of equipment, essential drugs and perioperative routines.

Paediatric Agranulocytosis Associated with Metamizole Treatment

PURPOSE

Metamizole, which has antipyretic and pain-relieving properties, is generally used to treat fever in children who do not respond to paracetamol treatment. The most remarkable side effect of metamizole is that it causes myelotoxicity independently of dose. In this study, we aimed to present the clinical features of paediatric patients who developed agranulocytosis after the use of metamizole and draw attention to this side effect.

METHODS

The patients who were admitted to Eskişehir Osmangazi University Faculty of Medicine Hospital, Pediatric Infectious Diseases and Pediatric Hematology Service, between January 1, 2015, and December 31, 2018, with a diagnosis of secondary agranulocytosis to metamizole use were examined retrospectively.

RESULTS

In all, 12 patients were included in the study; oral metamizole was used in these patients for fever reduction. The mean absolute neutrophil count was 225/mm³ ± 226 (0-600/mm³) at admission, and the neutrophil value of 11 patients was < 500/mm³. The mean length of hospitalisation of the patients was 9.92 ± 8 (3-28) days. Eight patients received intravenous antibiotic therapy and four patients received at least one of the following treatments: intravenous immunoglobulin, granulocyte colony-stimulating factor and methylprednisolone. Bone marrow aspiration examination showed neutrophil/band maturation delaying in the myeloid series with normocellular bone marrow in three patients. Hypocellularity in the bone marrow and decrease in myeloid precursors were observed in three patients. There were no fatal cases.

CONCLUSION

The development of agranulocytosis after the use of metamizole causes long-term hospitalisation and may require the use of medications in treatment management. Considering the availability of alternative options to treat fever and pain, and given the side-effect profile of metamizole, it should not be the preferred, first-line antipyretic treatment in children.

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.

Approaching acute pain in emergency settings; European Society for Emergency Medicine (EUSEM) guidelines-part 2: management and recommendations

BACKGROUND

In Europe, healthcare systems and education, as well as the clinical care and health outcomes of patients, varies across countries. Likewise, the management of acute events for patients also differs, dependent on the emergency care setting, e.g. pre-hospital or emergency department. There are various barriers to adequate pain management and factors common to both settings including lack of knowledge and training, reluctance to give opioids, and concerns about drug-seeking behaviour or abuse. There is no single current standard of care for the treatment of pain in an emergency, with management based on severity of pain, injury and local protocols. Changing practices, attitudes and behaviour can be difficult, and improvements and interventions should be developed with barriers to pain management and the needs of the individual emergency setting in mind.

METHODS

With these principles at the forefront, The European Society for Emergency Medicine (EUSEM) launched a programme-the European Pain Initiative (EPI)-with the aim of providing information, advice, and guidance on acute pain management in emergency settings.

RESULTS AND CONCLUSIONS

This article provides treatment recommendations from recently developed guidelines, based on a review of the literature, current practice across Europe and the clinical expertise of the EPI advisors. The recommendations have been developed, evaluated, and refined for both adults and children (aged ≥ 1 year, ≤ 15 years), with the assumption of timely pain assessment and reassessment and the possibility to implement analgesia. To provide flexibility for use across Europe, options are provided for selection of appropriate pharmacological treatment.

High-Throughput Sequencing to Investigate Associations Between HLA Genes and Metamizole-Induced Agranulocytosis

Background and Objective: Agranulocytosis is a rare and potentially life-threatening complication of metamizole (dipyrone) intake that is characterized by a loss of circulating neutrophil granulocytes. While the mechanism underlying this adverse drug reaction is not well understood, involvement of the immune system has been suggested. In addition, associations between genetic variants in the Human Leukocyte Antigen (HLA) region and agranulocytosis induced by other drugs have been reported. The aim of the present study was to assess whether genetic variants in classical HLA genes are associated with the susceptibility to metamizole-induced agranulocytosis (MIA) in a European population by targeted resequencing of eight HLA genes.

Design: A case-control cohort of Swiss patients with a history of neutropenia or agranulocytosis associated with metamizole exposure (n = 53), metamizole-tolerant (n = 39) and unexposed controls (n = 161) was recruited for this study. A high-throughput resequencing (HTS) and high-resolution typing method was used to sequence and analyze eight HLA loci in a discovery subset of this cohort (n = 31 cases, n = 38 controls). Identified candidate alleles were investigated in the full Swiss cohort as well as in two independent cohorts from Germany and Spain using HLA imputation from genome-wide SNP array data. In addition, variant calling based on HTS data was performed in the discovery subset for the class I genes HLA-A, -B, and -C using the HLA-specific mapper hla-mapper.

Results: Eight candidate alleles (p < 0.05) were identified in the discovery subset, of which HLA-C^∗04:01 was associated with MIA in the full Swiss cohort (p < 0.01) restricted to agranulocytosis (ANC < 0.5 × 10⁹/L) cases. However, no candidate allele showed a consistent association in the Swiss, German and Spanish cohorts. Analysis of individual sequence variants in class I genes produced consistent results with HLA typing but did not reveal additional small nucleotide variants associated with MIA.

Conclusion: Our results do not support an HLA-restricted T cell-mediated immune mechanism for MIA. However, we established an efficient high-resolution (three-field) eight-locus HTS HLA resequencing method to interrogate the HLA region and demonstrated the feasibility of its application to pharmacogenetic studies.

[Agranulocytosis after use of metamizole - an underestimated risk?]

OBJECTIVE

Metamizole was the second most common drug prescribed in Germany in 2018 despite the known risk of agranulocytosis and the strict indication. According to Stammschulte et al. up to 25 % of all prescriptions are off-label use. Although mandatory according to the prescribing information of metamizole, regular blood cell counts are not performed in up to 50 % of the patients with long-term use of this drug.

MATERIAL AND METHODS

Retrospective analysis of eight cases metamizole-induced agranulocytosis over a period of five years (2016-2020) in the university ENT department in Erlangen. Five patients were men and three women. Mean age of diagnosis was 52,4 years (± 25,6).

RESULTS

Agranulocytosis after use of metamizole is a serious adverse drug reaction that may affect patients of all ages. Frequently, only distinct clinical symptoms such as temperature of unknown origin, dysphagia and tonsillitis in combination with abscesses in the head and neck area result in the detection of a metamizole-induced agranulocytosis. An agranulocytosis provokes partially radical surgery and/ or intensive-care measures and could lead to sepsis with organ failure or even to death.

CONCLUSIONS

These patient cases show that agranulocytosis is a dangerous or even deadly adverse drug reaction after use of metamizole. Although the risk of agranulocytosis appears to increase with duration of use, we would recommend patient education as well as documentation of even a single administration of metamizole. This may facilitate early diagnosis of metamizole-induced agranulocytosis and thus prevent the onset of severe complications with possible lethal outcome.

Regional Differences in Prescribing Patterns of Metamizole in Germany Based on Data from 70 Million Persons

The non-opioid analgesic metamizole (dipyrone) is commonly used in Germany despite its narrow indications and market withdrawal from several countries. In this study we analyzed prescribing patterns of metamizole focusing on regional differences. The source of data was the “Information system for health care data” which includes data from the statutory health insurance funds for about 70 million Germans. We received aggregated data of individuals with at least one metamizole prescription in 2010 as well as the number of prescribed packages by age, sex, state and district along with the number of insured persons in each stratum. We calculated prescription prevalence stratified by age, sex, state and district. Among 68.4 million insured persons (mean age: 43.6 years; 53.0% female) 5.5 million received at least one metamizole prescription (8.1%, overall 12.2 million packages). Prevalence increased with age, and women received metamizole more often than men. In adults (total prevalence: 9.4%), levels varied between 7.0% (Saxony) and 11.1% (Schleswig-Holstein), whereas on a district level use ranged from 4.3% to 14.3%. In 2010, one of 12 individuals received metamizole at least once. Noticeable were the large regional variations which certainly cannot be explained by patient-related factors.