Metamizol Aristo (Metamizole Sodium Monohydrate)

• Metamizole sodium acts as an analgesic and antipyretic within the pyrazolone class, addressing several acute pain and fever pathways.
• Acute pain: provides rapid relief of moderate to severe pain when other analgesics are inadequate.
• Fever: reduces elevated body temperature in febrile conditions.
• Colic and spasm‑related pain: relaxes smooth muscle and eases discomfort associated with gastrointestinal or biliary colic.

• Metamizole sodium inhibits cyclo‑oxygenase enzymes, reducing prostaglandin synthesis, which lowers inflammation and pain signaling. It also exerts central analgesic activity through modulation of spinal and supraspinal pathways, although the precise central mechanisms remain incompletely defined. The combined peripheral COX inhibition and central effects contribute to its antipyretic and spasmolytic properties.

Metamizole sodium may cause a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Nausea: mild gastrointestinal upset.
• Dizziness: transient light‑headedness.
• Skin rash: mild erythema or itching.
• Headache: occasional tension‑type pain.

Serious or Rare Side Effects

• Agranulocytosis: severe reduction in white blood cells, potentially life‑threatening.
• Aplastic anemia: bone‑marrow failure requiring immediate medical attention.
• Severe cutaneous adverse reactions: Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Anaphylaxis: acute allergic reaction with respiratory or circulatory compromise.

• When prescribing Metamizol sodium, clinicians should consider several safety measures to minimize risk.
• Renal impairment: assess kidney function and adjust use in severe disease.
• Hepatic dysfunction: monitor liver enzymes during prolonged therapy.
• Hematologic monitoring: perform regular complete blood counts to detect early agranulocytosis.
• Allergy history: avoid in patients with known hypersensitivity to pyrazolones.
• Pregnancy and lactation: use only if potential benefit justifies potential risk to fetus or infant.
• Store at below 25°C: keep in original packaging, protect from moisture and direct sunlight.

Metamizol sodium can interact with other medicines, influencing efficacy or safety.

Major Interactions (Avoid)

• Cytotoxic chemotherapy agents: additive bone‑marrow suppression increasing risk of agranulocytosis.
• Warfarin: potentiates anticoagulant effect, raising bleeding risk.
• Sulfonamide antibiotics: combined risk of severe blood dyscrasias.

Moderate Interactions (Monitor Closely)

• ACE inhibitors: may enhance hypotensive effects.
• Diuretics: possible electrolyte disturbances.
• Other NSAIDs or analgesics: increased gastrointestinal irritation and renal stress.