ABSTRACT
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.
ABSTRACT
Postoperative pain is one of the main negative symptoms resulting from surgery and the use of new methods to control this symptom is of ever-increasing relevance. Opioid-sparing strategies, such as multimodal analgesia, are trends in this scenario. Pregabalin is a well-established treatment for neuropathic pain; however, it is still controversial in the surgical context for postoperative analgesia. This study investigated the effect of pregabalin on postoperative analgesia in patients undergoing abdominal hysterectomy. It is a prospective, randomised, double-blind, placebo-controlled clinical trial. Female patients undergoing abdominal hysterectomy were randomised to use pregabalin (group P1), 300 mg orally 2 h before surgery, or identical placebo pills (group P0). The main outcome includes the postoperative pain index by visual analogue scale (VAS) and McGill's pain questionnaire. Secondary outcomes include opioid consumption and the presence of adverse effects. A value of p < 0.05 was used to reject type I error. Fifty-five patients were randomised amongst the groups. Patients in group P1 had lower pain rates by VAS scale, both at rest and in active motion, than group P0. In McGill's questionnaire, patients from group P1 also had lower pain rates (12 × 28.5). There was approximately twice as much opioid consumption amongst patients in group P0. Regarding side effects, there was a difference between the two groups only for dizziness, being more incident in group P1. This study suggests that pregabalin is an important adjuvant drug in treating postoperative pain in patients with abdominal hysterectomy.
