Adult: As metamizole Na: 1 g up to 4 times daily or 2.5 g bid given via IV inj over 5 minutes or via IM inj. Adjust dose based on severity and patient response. Max: 5 g daily. Child: As methimazole Na: ≥3 months Dosage varies based on body weight. Refer to individual product literature for detailed guidelines.
Oral Fever, Severe pain
Adult: As metamizole Na: 0.5-1 g up to 3-4 times daily. Max: 4 g daily. Max treatment duration: 3-5 days. Child: As methimazole Na drops: ≥3 months Dosage varies based on body weight. Recommended dose: 8-16 mg/kg as single dose, may repeat if necessary, up to 3 or 4 times daily. Refer to individual product literature for detailed guidelines.
Renal Impairment
IV/IM Severe pain; Fever: Severe: Contraindicated.
Hepatic Impairment
IV/IM Severe pain; Fever: Severe: Contraindicated.
Administration
Should be taken with food.
Contraindications
Hypersensitivity (including rhinitis, asthma, urticaria) to metamizole, other pyrazolone derivatives, other NSAID(s), other analgesics. Bone marrow suppression or haematopoietic disorders (e.g. aplastic anaemia, agranulocytosis, leucopenia), deficiency, porphyria; hypotension, unstable CV condition (IV/IM). Severe hepatic and renal impairment (IV/IM). Children <3 months of age or <5 kg body weight. Pregnancy and lactation.
Special Precautions
Patient with hypotonia, hypovolaemia, dehydration, unstable CV condition, gastric and duodenal ulcer, bronchial asthma, alcohol intolerance. Mild to moderate hepatic and renal impairment. Children.
Adverse Reactions
Significant: Hypotensive reactions. Blood and lymphatic system disorders: Rarely, leucopenia. Cardiac disorders: Chest pain, arrhythmias. Gastrointestinal disorders: Nausea, vomiting, dyspepsia, abdominal pain. General disorders and administration site conditions: Mucosal inflammation, fever, chills. Metabolism and nutrition disorders: Porphyria. Nervous system disorders: Dizziness, vertigo. Renal and urinary disorders: Red-colored urine; rarely, anuria, oliguria, proteinuria, acute kidney failure, interstitial nephritis. Respiratory, thoracic and mediastinal disorders: Sore throat, dyspnoea, bronchospasm. Skin and subcutaneous tissue disorders: Erythema, pruritus, rash, burning sensation, local oedema, urticaria. Potentially Fatal: Rarely, hypersensitivity reactions (e.g. anaphylactic shock), Stevens-Johnson syndrome, Lyell’s syndrome, haemolytic anaemia, aplastic anaemia, agranulocytosis, thrombocytopenia, pancytopenia.
Patient Counseling Information
This drug may impair concentration, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor CBC including differential; for signs and symptoms of hypersensitivity, hypotensive reactions and skin related adverse reactions.
Overdosage
Symptoms: Nausea, vomiting, headache, weakness, fever, abdominal pain, renal impairment, acute kidney failure, interstitial nephritis; rarely, somnolence, vertigo, spasms, coma, convulsions, hypotension, shock, tachycardia. Management: May decrease absorption by performing gastric lavage or by giving activated carbon. May eliminate MAA from the body through haemodialysis, haemoperfusion, haemofiltration or plasma filtration. Give symptomatic and supportive treatment.
Drug Interactions
Risk of thrombocytopenia with anticoagulants. Risk of severe hypothermia with other phenothiazines, chlorpromazine. Increased effect/toxicity with TCA(s), oral contraceptives, MAOI(s), allopurinol. Decreased effect with barbiturates, glutethimide, phenylbutazone. Increases haematotoxicity effects of methotrexate. Increases effects of oral antidiabetic agents, sulfonamides, phenytoin. Decreases levels of bupropion, ciclosporin.
Food Interaction
Increased effect with alcohol. Avoid alcohol.
Action
Description: Metamizole, an NSAID, has analgesic, antipyretic and anti-inflammatory properties. It reduces prostaglandin synthesis by inhibiting cyclooxygenase (COX)-1 and 2. It also stimulates the secretion of β-endorphins by the pituitary hypothalamus, reduces the level of endogenous pyrogens and affects the thermoregulation centre in the hypothalamus.
Synonym: dipyrone, sulpyrine. Pharmacokinetics: Absorption: Hydrolysed in the gastrointestinal tract to the active metabolite 4-methyl-amino-antipyrine (MAA). Bioavailability: Approx 90% (MAA). Time to peak plasma concentration: 1-2 hours (oral). Distribution: Crosses the placenta and enters breastmilk. Plasma protein binding: 58% (MAA), 48% [4-amino-antipyrine (AA)], 14% [4-acetylamino-antipyrine (AAA)] and 18% [formyl-amino-antipyrine (FAA)]. Metabolism: Metabolised in the liver into 4-formyl-amino-antipyrine (FAA) and other metabolites. Excretion: Mainly via urine (approx 90% as metabolites); faeces (approx 10%). Plasma elimination half-life: Approx 14 minutes (IV).
Chemical Structure
Metamizole Source: National Center for Biotechnology Information. PubChem Database. Metamizole, CID=3111, https://pubchem.ncbi.nlm.nih.gov/compound/Metamizole (accessed on Jan. 22, 2020)
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