Metamizole, even after 100 years on the market, remains an important component of postoperative pain therapy
Metamizole has been used in the therapy of a wide range of acute and chronic pains for 100 years. Thanks to a number of advantages, it still represents one of the most frequently used analgesics in daily clinical practice.
A century-old 'elder' that's still fit
Metamizole was first introduced to the clinical market in 1922, making this year its notional anniversary - celebrating 100 years in the field of analgesic therapy. During this long period, there has been a rapid development in the field of analgesic therapy, with the emergence of a separate field of algology dealing with pain treatment and the introduction of many new analgesics into clinical practice. Despite significant advancements in understanding and managing pain, metamizole still represents one of the most popular analgesics due to its favorable pharmacological properties. Statistics on the current prescription of analgesics attest to this - for example, in Germany, Spain, Slovakia, and other European Union countries, it is among the most frequently prescribed analgesics. According to the ranking of human medicines consumption published by the Slovak National Center for Health Information, it was the 4th most frequently prescribed drug in Slovakia in 2020.
This non-addictive pyrazolone analgesic also has antipyretic and spasmolytic effects and is indicated for the treatment of severe acute pain, including colicky pain, chronic pain, and fever unresponsive to other treatments. The advantage of this drug is the minimal number of side effects and the possibility of longer-term use. It also combines very well with other analgesics to achieve optimal pain therapy results. It is the drug of choice for visceral pain, thanks in part to its spasmolytic effect. Generally, however, it is used in the treatment of a wide range of pains, such as headaches, musculoskeletal pain, or neuropathic pain.
Clinical evaluations in managing (not only) postoperative pain
Metamizole plays an important role in the therapy of postoperative pain across various areas. To this day, numerous studies have been published evaluating the efficacy and safety of metamizole in the treatment of postoperative pain and comparing its administration with other analgesics.
Torres et al. published a study in which they evaluated the efficacy and safety of metamizole compared to tramadol in patients after hysterectomy. The multicenter randomized double-blind study involved 151 women aged 18-60 years who underwent abdominal hysterectomy. Analgesic treatment was evaluated in the 24-hour period post-surgery. Compared to the opioid analgesic, metamizole achieved comparable efficacy. However, patients on tramadol had a significantly higher incidence of gastrointestinal side effects (42.1% vs. 20.2%; p<0.05) and a greater need for antiemetic ondansetron to control nausea and vomiting.
Oreškovićová et al. evaluated the efficacy of metamizole and paracetamol in combination with opioid analgesics in patients after total hip replacement during the 24 hours post-surgery. This study also demonstrated higher efficacy in relieving postoperative pain in the group using metamizole. An important conclusion of the study is also the mention that the administration of metamizole compared to intravenously administered paracetamol was a less costly method of analgesic therapy.
Stankov et al. evaluated the efficacy of metamizole compared to tramadol and butylscopolamine in the treatment of pain in acute renal colic. A total of 104 patients were randomized to therapy with metamizole at a dose of 2.5 g, tramadol at a dose of 100 mg, or butylscopolamine at a dose of 20 mg. The administration of metamizole was associated with a significant analgesic effect compared to other treatment modalities and a significantly lower number of patients requiring rescue medication. The favorable safety profile of metamizole was also confirmed, with adverse effects developing in only 1 patient.
Conclusion
Despite significant progress in medicine since the introduction of metamizole into clinical practice, this medication still represents one of the most frequently prescribed analgesics. The reason is its favorable pharmacological profile with a minimal number of side effects and comparable analgesic efficacy compared to other types of analgesics, including opioids.
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Sources:
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2. NCZI. Rankings of human medicines consumption in the Slovak Republic until 2020. Národné centrum zdravotníckych informácií, 23. 9. 2021. Available at: www.nczisk.sk/Statisticke_vystupy
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6. Orešković Z., Bićanić G., Hrabač P. et al. Treatment of postoperative pain after total hip arthroplasty: comparison between metamizole and paracetamol as adjunctive to opioid analgesics - prospective, double-blind, randomized study. Arch Orthop Trauma Surg 2014; 134 (5): 631–636, doi: 10.1007/s00402-014-1979-7.
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