Safety of Metamizole in Adult Patients – Meta-analysis of 79 Studies
Metamizole is a non-opioid analgesic with antipyretic and spasmolytic effects that has been used for over 100 years. It is approved for the treatment of children and adults in various dosage forms. German authors conducted a systematic literature review and meta-analysis of clinical studies to evaluate its safety compared to placebo and other analgesics in adult patients.
Systematic Literature Review and Meta-analysis
The authors conducted a systematic review in the databases CENTRAL, MEDLINE, EMBASE, CINAHL and several clinical trial registries. They also reviewed the literature lists of previously published reviews. The meta-analysis included randomized controlled trials that compared metamizole administered to adults in any form and for any indication with another analgesic or with placebo. Data were extracted on study design, sample size, analgesic indication, patient characteristics, and therapeutic regimen. The occurrence of adverse events, serious adverse events, and cases of treatment discontinuation were assessed. Separate meta-analyses comparing metamizole with each individual comparator were also conducted. The primary endpoint was the occurrence of any adverse events during the study.
Studies Evaluated
Of 696 potential works, 79 studies involving nearly 4,000 patients treated with metamizole for less than 2 weeks met the inclusion criteria. The average age of patients ranged between 22 and 64 years, with females comprising 45.8% of the population. A total of 3,716 patients used metamizole, 1,077 placebo, 303 acetylsalicylic acid (ASA), 1,983 nonsteroidal anti-inflammatory drugs (NSAIDs), 829 opioids, 362 paracetamol, and 156 other analgesics. The vast majority of studies were conducted in hospitalized patients.
Findings
A lower incidence of adverse events was noted for metamizole compared to opioids (relative risk [RR] 0.79; 95% confidence interval [CI] 0.79–0.96). Adverse event rates for metamizole were comparable with placebo (RR 0.96; 95% CI 0.73–1.25), paracetamol (RR 1.08; 95% CI 0.69–1.68), ASA (RR 0.80; 95% CI 0.44–1.45), and NSAIDs (RR 0.91; 95% CI 0.79–1.05).
Only a few serious adverse events were described, with no difference in incidence between metamizole and other analgesics. No cases of agranulocytosis or deaths related to metamizole administration were found.
Conclusion
Short-term administration of metamizole, primarily in hospitalized adult patients (for example, for the treatment of renal colic or postoperative pain), appears to be a safe choice compared to other analgesics.
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Source: Kötter T., da Costa B. R., Fässler M. et al. Metamizole-associated adverse events: a systematic review and meta-analysis. PLoS One 2015; 10 (4): e0122918, doi: 10.1371/journal.pone.0122918.
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MAT-CZ-2400510 – 1.0 – 05/2024
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