Metamizole (Dipyrone) and the Liver: A Review of the Literature

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.

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.

Use of metamizole and other non-opioid analgesics in Switzerland between 2014 and 2019: an observational study using a large health insurance claims database

OBJECTIVE

To investigate claims patterns for metamizole and other non-opioid analgesics in Switzerland. To characterise users of these non-opioid analgesics regarding sex, age, comedications and canton of residence.

METHODS

We conducted a retrospective descriptive study using administrative claims data of outpatient prescribed non-opioid analgesics of the Swiss health insurance company Helsana between January 2014 and December 2019. First, we evaluated the number of claims and defined daily doses  per year of metamizole, ibuprofen, diclofenac and paracetamol in adults aged 18 years or over. Second, we characterised new users of these non-opioid analgesics in terms of sex, age, claimed comedications and canton of residence.

RESULTS

From 2014 to 2019, among the investigated non-opioid analgesics, metamizole showed the highest increase in claims (+9545 claims, +50%) and defined daily doses (+86,869 defined daily doses, +84%) per 100,000 adults. Metamizole users had the highest median age (62 years [IQR: 44-77]) compared to ibuprofen (47 years [IQR: 33-62]), diclofenac (57 years [IQR: 43-71]) and paracetamol (58 years [IQR: 39-75]) users. Metamizole users also more frequently claimed proton pump inhibitors, anticoagulants, platelet aggregation inhibitors and antihypertensive drugs than users of other non-opioid analgesics. While metamizole was most frequently claimed in German-speaking regions of Switzerland, ibuprofen and paracetamol were most frequently claimed in the French-speaking regions and diclofenac in German- and Italian-speaking regions.

CONCLUSION

In Switzerland, metamizole was increasingly claimed between 2014 and 2019. Metamizole was most frequently claimed by older adults and patients with comedications suggestive of underlying conditions, which can be worsened or caused by use of nonsteroidal anti-inflammatory drugs. The lack of studies regarding the effectiveness and safety of metamizole in this population warrants further investigation.

A protocol for directly accessing geminal C-4 diarylated pyrazol-5(4H)-ones via tandem C-H aryne insertion and their inceptive neurobiological evaluation

Geminal C-4 diarylation of substituted pyrazol-5(4H)-ones with in situ generated arynes as the aryl source has been achieved in a one-flask operation. All the newly accessed C4-gem-diarylated pyrazolone entities were found to be non-cytotoxic with varying AChE enzyme inhibitory activities and BBB permeability attributes that augur well for further advancement towards CNS therapeutics for untreatable disorders.

Pharmacotherapeutic monitoring of dipyrone in northeastern Brazilian donkeys (Equus asinus)

This study aimed to monitor the effects of dipyrone following multiple administrations in northeastern donkeys. Ten castrated male donkeys, aged 6.4 ± 3 years and weighing 130.6 ± 9.8 kg, were administered dipyrone (25 mg/kg IV) every 12 h, resulting in six administrations (D1 to D6) per animal. Blood samples were collected over a 72 h monitoring period. A validated UHPLC-MS/MS method was employed to determine the plasma concentrations of the 4- methylaminoantipyrine (4-MAA) and 4-aminoantipyrine (4-AA). The calculated pharmacokinetic variables of 4-MAA after D1 and D6 were, respectively: Cmax (μg/mL) = 163.60 ± 179.72 and 178.79 ± 196.94; T1/2beta (h) = 2.65 ± 0.65 and 3.37 ± 1.03; and AUC0-t (μg/mL × h) = 240.38 ± 130.87 and 373.52 ± 78.85. The same variables for 4-AA were: Cmax, (μg/mL) = 0.44 ± 0.27 and 0.90 ± 0.31, T1/2beta (h) = 14.77 ± 13.13 and 35.97 and AUC0-t (μg/mL × h) = 3.20 ± 0.43 and 27.73 ± 11.99. Concentrations of 4-MAA exceeded the minimum concentration required for 50% inhibition of cyclooxygenases 1 and 2. However, an accumulation of 4-AA, was observed. Further clinical studies are necessary to ascertain the implications of these findings on the pharmacodynamic response to dipyrone in northeastern donkeys.

Adjuvants for balanced anesthesia in ambulatory surgery

Balanced anesthesia relies on the simultaneous administration of different drugs to attain an anesthetic state. The classic triad of anesthesia is a combination of a hypnotic, an analgesic, and a neuromuscular blocker. It is predominantly the analgesic pillar of this triad that became more and more supported by adjuvant therapy. The aim of this approach is to evolve into an opioid-sparing technique to cope with undesirable side effects of the opioids and is fueled by the opioid epidemic. The optimal strategy for balanced general anesthesia in ambulatory surgery must aim for a transition to a multimodal analgesic regimen dealing with acute postoperative pain and ideally reduce the most common adverse effects patients are faced with at home; sore throat, delayed awakening, memory disturbances, headache, nausea and vomiting, and negative behavioral changes. Over the years, this continuum of "multimodal general anesthesia" adopted many drugs with different modes of action. This review focuses on the most recent evidence on the different adjuvants that entered clinical practice and gives an overview of the different mechanisms of action, the potential as opioid-sparing or hypnotic-sparing drugs, and the applicability specifically in ambulatory surgery.

Case report: Generalized bullous fixed drug eruption mimicking epidermal necrolysis

Generalized bullous fixed drug eruption (GBFDE) is the most severe form of fixed drug eruption and can be misdiagnosed as epidermal necrolysis (EN). We report the case of a 42-year-old male patient presenting with more than 50% skin detachment without defined areas of exanthema or erythema and a history of one prior event of EN caused by acetaminophen (paracetamol), allopurinol, or amoxicillin 1.5 years ago. The initial diagnosis was GBFDE or EN. The histology of a skin biopsy was unable to distinguish between the two diseases. The course of the disease, the later clinical presentation, and the medical and medication history, however, were in favor of a diagnosis of GBFDE with two potentially culprit drugs: metamizole and ibuprofen. Moxifloxacin, enoxaparin sodium, hydromorphone, and insulin human were administered concomitantly, which makes them suspicious as well. Unfortunately, the patient received an additional dose of metamizole, one of the possible causative drugs, and he developed another bullous reaction within 1 month. This led to the diagnosis of GBFDE due to metamizole. This report highlights the challenges of distinguishing two rare diseases and elucidates the importance of distinct clinical presentation and detailed medication history.

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.

5-Alkoxy-1-aryl-3-polyfluoroalkylpyrazoles with Antinociceptive Activity: Partial Agonists of TRPV1 Ion Channels

Chemoselective O-alkylation of 1-aryl-3-polyfluoroalkylpyrazol-5-oles under basic conditions resulted in a series of 5-alkoxypyrazoles (26 derivatives). They showed an acceptable ADME profile (in silico) and can be considered as drug-like. In experiments in vivo (CD-1 mice), it was found that the obtained compounds do not have toxic properties at a dose of more than 150 mg/kg (for most compounds at a dose of >300 mg/kg, and for lead compounds - >600 mg/kg). 22 Compounds from this series demonstrated from moderate to high analgesic effects (28-104 % at 1 h and 37-109 % at 2 h after administration) in vivo in the hot plate test (SD rats, 15 mg/kg, intraperitoneal (ip)). The lead compound was 4-([1-phenyl-3-(trifluoromethyl)pyrazol-5-yl]oxy)butan-1-ol, which not only increased the latent period in the hot plate test by 103 % at both measurement points but also showed a pronounced analgesic effect under conditions of capsaicin-induced nociception (CD-1 mice, 15 mg/kg, ip). According to molecular modeling, all synthesized compounds can interact with the TRPV1 ion channel. This biological target was confirmed in in vitro experiments on Chinese hamster ovary cells expressing rTRPV1. 5-Alkoxypyrazoles were partial agonists of the TRPV1 ion channel in various degree, and the most active was the same pyrazole as in in vivo tests.

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.

Endometriosis and Opioid Receptors: Are Opioids a Possible/Promising Treatment for Endometriosis?

Endometriosis (EM), defined as the presence of endometrial-like tissue with surrounding smooth muscle cells outside the uterus, is a disregarded gynecological disease reported to affect 6-10% of women of reproductive age, with 30-50% of them suffering from chronic pelvic pain and infertility. Since the exact pathogenic mechanisms of EM are still unclear, no curative therapy is available. As pain is an important factor in EM, optimal analgesia should be sought, which to date has been treated primarily with non-steroidal anti-inflammatory drugs (NSAIDs), metamizole or, in extreme cases, opioids. Here, we review the pain therapy options, the mechanisms of pain development in EM, the endogenous opioid system and pain, as well as the opioid receptors and EM-associated pain. We also explore the drug abuse and addiction to opioids and the possible use of NOP receptors in terms of analgesia and improved tolerability as a target for EM-associated pain treatment. Emerging evidence has shown a promising functional profile of bifunctional NOP/MOP partial agonists as safe and nonaddictive analgesics. However, until now, the role of NOP receptors in EM has not been investigated. This review offers a thought which still needs further investigation but may provide potential options for relieving EM-associated pain.

Analysis of umbilical cord tissue as an indicator of in utero exposure to toxic adulterating substances

In utero drug exposure is a significant public health threat to the well-being and normal development of the neonate. Recently, testing of umbilical cord tissue (UCT) has been employed to measure illicit drug exposure, as drugs used by the mother during the third trimester may be retained in the UCT. Focus has also been given to potential adverse health effects among drug users, resulting from exposure to pharmacologically active adulterants and cutting agents in the street drug supply. The in utero effects of these substances have not been well studied in humans, nor has their presence been demonstrated as a means for assessing adverse health effects in the neonate. Here, we describe the application of a novel test method to analyze UCT for the presence of more than 20 common adulterating/cutting substances via LC/Q-TOF. In total, 300 de-identified UCT samples were analyzed-all had previously tested positive for cocaine or opiates. Generally, the positivity rates of individual compounds were similar between the Cocaine and Opiates Subgroups, apart from levamisole, xylazine, dipyrone (metabolites), and promethazine. Many of the adulterants used in the street drug supply do have legitimate medicinal/therapeutic uses, including several of the compounds most frequently detected in this study. Caffeine and lidocaine were the most frequently identified compounds both individually (>70% each) and in combination with each other. Alternatively, levamisole, an adulterant with no legitimate therapeutic use, was present in 12% of cases. Importantly, this data demonstrates that the detection of traditional drugs of abuse may serve as indicators of potential in utero exposure to toxic adulterating substances during gestation. While there is cause for concern with respect to any unintentional drug exposure, illicit drug use during pregnancy, including uncontrolled dosing, poly-adulterant consumption, and the interactions of these drug mixtures, produces a significant public health threat to the neonate which warrants further study.

Pain Management and Analgesics Used in Small Mammals during Post-Operative Period with an Emphasis on Metamizole (Dipyrone) as an Alternative Medication

Metamizole (dipyrone) is a widely used non-opioid analgesic in both human and animal medicine. Metamizole's safety has been the topic of numerous opposing debates, given the fact that in certain countries metamizole is frequently used as an over-the-counter (OTC) medicine, while in others it is banned due to the risk of agranulocytosis. Further, small mammals such as rabbits, ferrets, rodents, and hedgehogs have become some of the most common pets present in veterinary practice, and each of these species has specific analgesic needs due to their anatomy and physiology. The key to providing appropriate medical care is in finding a substance that has minimal negative effects. In small mammals, analgesia is an important factor and, it happens frequently that, pain in these patients is not well managed. Post-operative pain management is an important topic in the welfare of animals. The objectives of this review, thus, were to provide a concise overview of analgesics that are used in the treatment of postoperative pain in small mammals (e.g., rabbits and rodents) and to highlight the importance of this product, metamizole, in veterinary medicine, as well as the potential of this substance as an alternative analgesic for the treatment of postoperative pain in small mammals.

Positive Patient Postoperative Outcomes with Pharmacotherapy: A Narrative Review including Perioperative-Specialty Pharmacist Interviews

The influence of pharmacotherapy regimens on surgical patient outcomes is increasingly appreciated in the era of enhanced recovery protocols and institutional focus on reducing postoperative complications. Specifics related to medication selection, dosing, frequency of administration, and duration of therapy are evolving to optimize pharmacotherapeutic regimens for many enhanced recovery protocolized elements. This review provides a summary of recent pharmacotherapeutic strategies, including those configured within electronic health record (EHR) applications and functionalities, that are associated with the minimization of the frequency and severity of postoperative complications (POCs), shortened hospital length of stay (LOS), reduced readmission rates, and cost or revenue impacts. Further, it will highlight preventive pharmacotherapy regimens that are correlated with improved patient preparation, especially those related to surgical site infection (SSI), venous thromboembolism (VTE), nausea and vomiting (PONV), postoperative ileus (POI), and emergence delirium (PoD) as well as less commonly encountered POCs such as acute kidney injury (AKI) and atrial fibrillation (AF). The importance of interprofessional collaboration in all periprocedural phases, focusing on medication management through shared responsibilities for drug therapy outcomes, will be emphasized. Finally, examples of collaborative care through shared mental models of drug stewardship and non-medical practice agreements to improve operative throughput, reduce operative stress, and increase patient satisfaction are illustrated.

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.

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.

An overview of the use and misuse/abuse of opioid analgesics in different world regions and future perspectives

Opioids are an important therapeutic option for severe resistant chronic pain but, in the absence of proper oversight, their use has risks. The level of prescription opioid misuse/abuse differs among countries, due to differences in healthcare systems and pain management approaches. However, evaluating the true dimension of prescription opioid misuse/abuse is complicated by statistical reporting which often does not differentiate between prescription and illicit opioid use, or between prescription opioid use by patients and nonpatients, highlighting a need for greater uniformity. Parallel efforts to educate patients and the general public about opioid risks, facilitate appropriate analgesic prescribing and identify alternative formulations or options to use instead of or with opioids, may contribute to optimizing prescription opioid use for pain management.

Analytical findings in a non-fatal intoxication with the synthetic cannabinoid 5F-ADB (5F-MDMB-PINACA): a case report

The case report centres on analytical findings from a spice sample (mixed with tobacco (as a cigarette) for consumption), and its corresponding plasma sample, smoked by a 31-year-old man who was attended by emergency services following collapse. The man was fully conscious and cooperative during initial medical treatment. Suddenly, he suffered a complete loss of self-control, whereupon the police was notified. The man encountered the police officers when exiting the apartment, at which point he threatened them with clenched fists and reached for a plant bucket in order to strike out in the direction of the officers. At the trial, he described himself as confused and as being completely overwhelmed, having lost self-control, suffered a panic attack and “just wanted to get out the situation”. Furthermore, he stated that he had no recollection of the incident. He feared death due to palpitations, heart pain, dizziness and repetitive anxiety states. Routine systematic as well as extended toxicological analysis of the plasma sample, taken approximately 2 h after the incident, confirmed the use of cannabis and spice. Plasma concentrations of THC, OH-THC and THC-COOH were 8.0 μg/L, 4.0 μg/L and 147 μg/L, respectively. Furthermore, analysis confirmed uptake of 5F-ADB (5F-MDMB-PINACA) via detection of both 5F-ADB and the 5F-ADB N-(5-OH-pentyl) metabolite. The spice sample additionally contained 5F-MDMB-PICA, which was not detected in the plasma sample. A differentiation between a possible co-use and a recent use of cannabis was not possible. In summary, this case once more underlines the health risks of spice use.

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.

NAT2 polymorphisms as a cause of metamizole-induced agranulocytosis

Metamizole is a widely prescribed NSAID with excellent analgesic and antipyretic properties. Although very effective, it is banned in some countries because of the risk for severe agranulocytosis. We here describe three patients with metamizole-associated agranulocytosis. Patient #1 suffered from agranulocytosis and tonsillitis followed by severe sepsis by Streptococcus pneumoniae and Epstein-Barr virus reactivation. Her dizygotic twin sister (patient #2) also suffered from agranulocytosis after a surgical intervention. Patient #3 initially had a tonsillitis and also developed neutropenia after metamizole intake. For all patients, pharmacogenetic diagnostic for the genes CYP2C9, CYP2C19 and NAT2, which are involved in metamizole metabolism and degradation of toxic metabolites, was initiated. Pharmacogenetic analysis revealed NAT2 slow acetylator phenotype in all three patients. Additionally, patient #2 is an intermediate metabolizer for CYP2C19 and patient #3 is a poor metabolizer for CYP2C9. Impairment of these enzymes causes a reduced degradation of toxic metabolites, for example, 4-methylaminoantipyrine (4-MAA) or 4-aminoantipyrine. The metabolite 4-MAA can complex with hemin, which is an early breakdown product during hemolysis. Hemolysis is often observed during invasive infections or after surgical procedures. It is known that the 4-MAA/hemin complex can induce cytotoxicity in the bone marrow and interrupt granulocyte maturation. In conclusion, metamizole-induced agranulocytosis most likely was a consequence of the underlying genetical predisposition, that is, polymorphisms in the genes NAT2, CYP2C9 and CYP2C19. Hemolysis may have increased the toxicity of metamizole metabolites.

Is There an Increased Risk of Hepatotoxicity with Metamizole? A Comparative Cohort Study in Incident Users

INTRODUCTION

The analgesic metamizole, which has been withdrawn from the market in several countries due to the risk of agranulocytosis but is still available on the market in Germany and some other countries, has been associated with liver injury in published case reports; however, epidemiological studies on the risk of liver injury are limited.

OBJECTIVE

The aim of this study was to compare the risk of liver injury up to 270 days after the first start of treatment with metamizole with the corresponding risk in patients starting treatment with paracetamol, using a retrospective cohort incident user design.

METHODS

The first prescription for either metamizole or paracetamol in the Intercontinental Medical Statistics (IMS)^® Disease Analyzer Germany database during the study period (2009-2018) was identified in patients with at least 365 days of observation and no prior diagnosis of liver events, cancer or HIV, or treatment within the last 6 months with hepatotoxic drugs typically administered for chronic conditions. Each patient was followed for specific liver events for 90 days after the prescription. In case of a new prescription within 90 days, a new 90-day observation period started, up to a maximum of 270 days. Cox regression was used to compare the risk of liver injury in the two groups.

RESULTS

Metamizole was associated with a higher risk of liver injury compared with paracetamol (adjusted hazard ratio 1.69, 95% confidence interval 1.46-1.97). Sensitivity analyses were performed to evaluate the robustness of these findings. In all the sensitivity analyses, metamizole was still associated with a higher risk of liver injury, including an analysis where naproxen was used as a comparator instead of paracetamol.

CONCLUSIONS

Results from this study support previous studies suggesting that metamizole is associated with a significant risk of liver injury. Nevertheless, a possible impact of residual confounding cannot be excluded.

Effects of dipyrone and acetylsalicylic acid on contractions of distal cauda epididymis duct, serum testosterone and sperm count in rats

The effects of dipyrone and acetylsalicylic acid (ASA) on male fertility are still not fully understood, mainly considering the epididymis as a putative target for their anti-fertility effects. Therefore, this study aimed to investigate the effects of dipyrone and ASA on the contractions of distal cauda epididymis duct, serum testosterone levels and sperm parameters in rats. Firstly, we checked the in vitro effects of dipyrone and ASA (10-1000 μM) on the contractions of distal cauda epididymis duct by pharmacological experiments. We also evaluated the effects of in vivo treatment with dipyrone and ASA 100 mg/kg (p.o.) for 15 days on epididymal duct contractions, serum testosterone levels and sperm parameters. In vitro dipyrone or ASA decreased the epididymal duct contractions induced by phenylephrine or carbachol. We observed that in vivo treatment with both drugs decreased the daily sperm production, serum testosterone levels and sperm count through epididymis without altering the epididymal duct contractions and sperm transit time through epididymis. In conclusion, in vitro dipyrone and ASA were able to diminish the contractions of epididymal duct, whilst in vivo administration decreased the sperm count throughout epididymis as a consequence of a low sperm production caused by reduced testosterone levels.

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.

Non-covalent binding and selective fluorescent sensing of dipyrone with a carbocyanine dye and cetyltrimethylammonium bromide

The work is aimed at the search of selective fluorescent sensors without using specific artificial receptors, antibodies, enzymes etc. With this end in view, methods based on non-covalent binding of target analytes are sought. We observed dramatic changes in the emission spectrum of a carbocyanine dye in a micellar surfactant solution (cetyltrimethylammonium bromide, CTAB) in the presence of dipyrone (metamizol, analgin): the 480 nm band intensity increases with a simultaneous decrease in intensity in near-IR region (720 nm). MALDI and NMR-¹H data show the intact molecules of dipyrone and the dye. The detection can be performed in the presence of other organic species and inorganic salts. Dipyrone testing is feasible within 5 × 10^-7-5 × 10^-4M with RSDs of 3.5% by using a visualizer instead of a spectrofluorimeter.

Arylamine N-acetyltransferase acetylation polymorphisms: paradigm for pharmacogenomic-guided therapy- a focused review

INTRODUCTION

The N-acetylation polymorphism has been the subject of comprehensive reviews describing the role of arylamine N-acetyltransferase 2 (NAT2) in the metabolism of numerous aromatic amine and hydrazine drugs.

AREAS COVERED

We describe and review data that more clearly defines the effects of NAT2 haplotypes and genotypes on the expression of acetylator phenotype towards selected drugs within human hepatocytes in vitro, within human hepatocyte cultures in situ, and clinical measures such as bioavailability, plasma metabolic ratios of parent to N-acetyl metabolite, elimination rate constants and plasma half-life, and/or clearance determinations in human subjects. We review several drugs (isoniazid, hydralazine, sulfamethazine, amifampridine, procainamide, sulfasalazine, amonafide and metamizole) for which NAT2 phenotype-guided therapy may be important. The value of pharmacogenomics-guided isoniazid therapy for the prevention and treatment of tuberculosis is presented as a paradigm for NAT2 phenotype-dependent dosing strategies.

EXPERT OPINION

Studies in human subjects and cryopreserved human hepatocytes show evidence for rapid, intermediate and slow acetylator phenotypes, with further data suggesting genetic heterogeneity within the slow acetylator phenotype. Incorporation of more robust NAT2 genotype/phenotypes relationships, including genetic heterogeneity within the slow acetylator phenotype, should lead to further advancements in both health outcomes and cost benefit for prevention and treatment of tuberculosis.

Accidental ingestion of methyl ethyl ketone peroxide: N-acetylcysteine treatment and toxicological analysis

INTRODUCTION

Methyl ethyl ketone peroxide (MEKP) is a highly toxic product which promotes tissue damage by uncontrolled free radical production.

CASE REPORT

A man accidentally ingested 110 ml of MEKP (37%) at his workplace after mistaking it with a bottle of water. A loading dose of N-acetylcysteine (NAC) and subsequent maintenance doses were applied at the hospital for three consecutive days. Biochemical and hematological parameters showed significant alterations. Tracheal intubation, gastric lavage and hemodialysis were not performed. Methyl ethyl ketone (MEK) and MEKP were detected in EDTA-blood samples by GC-FID and LC-QTOF/MS respectively. An endoscopy exam identified tissue damage. The patient was admitted to the hospital for 10 days. No sequelae were reported after the MEKP poisoning. Oral administration of NAC was successful as an antidote without another approach.

CONCLUSIONS

Although NAC treatment was successful, supervision after the hospitalization period was required according to the prognosis. Workplace conditions promoted anosmia, explaining the accident. MEKP and MEK were successfully detected in blood samples even with less-than-ideal storage conditions. Knowledge of MEKP dangerousness and good work practices can prevent accidental MEKP poisoning.

Acute intermittent porphyria: analgesia can be dangerous

Acute intermittent porphyria (AIP) is a rare condition, a metabolic disorder of the haem biosynthesis. An acute crisis of AIP can present as a combination of symptoms, such as abdominal pain, autonomic dysfunction, hyponatremia, muscle weakness and neurological symptoms in the absence of others obvious causes. We report the case of a 53-year-old woman, who was previously diagnosed with AIP 5 weeks after therapeutic suspension has developed an acute disease exacerbation. During hospitalisation, further exacerbation has occurred after analgesia with metamizole. Glucose and hemin infusions resulted in slow improvement. Physical rehabilitation was crucial to peripheral polyneuropathy recovery. Taking into account the porphyrinogenic effect described for metamizole, this drug might have triggered the second attack. Clinical history was sufficient to suspect the diagnosis and to start the treatment immediately, preventing important sequelae.