Metamizol Sodic Sanosan (Metamizole Sodium Monohydrate)

Metamizole is an analgesic and antipyretic that acts on the central pain and fever pathways.

• Pain: Provides relief of moderate to severe somatic and visceral pain, including postoperative and cancer‑related pain.
• Fever: Lowers elevated body temperature quickly, useful in acute febrile states.
• Post‑operative pain: Helps control pain after surgical procedures, facilitating recovery.
• Cancer‑related pain: May be used as part of multimodal analgesia for tumor‑associated discomfort.
• Acute colicky pain: Alleviates visceral colicky pain such as biliary or renal colic.

• Metamizole exerts its effect primarily by inhibiting cyclooxygenase enzymes, leading to reduced synthesis of prostaglandins that mediate pain and fever. The exact mechanism is not fully understood, but the drug also appears to modulate central nervous system pathways involved in nociception and thermoregulation, contributing to its analgesic and antipyretic actions. Additionally, Metamizole may influence peripheral inflammatory mediators and interact with opioid receptors, enhancing its overall analgesic profile.

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

Common Side Effects

• Nausea: mild gastrointestinal upset.
• Vomiting: occasional emesis.
• Dizziness: transient light‑headedness.
• Skin rash: mild erythematous reactions.
• Hypotension: temporary drop in blood pressure.

Serious or Rare Side Effects

• Agranulocytosis: severe reduction of white blood cells, potentially life‑threatening.
• Anaphylaxis: acute allergic reaction with respiratory compromise.
• Stevens‑Johnson syndrome: severe skin and mucous membrane disorder.
• Hepatotoxicity: liver enzyme elevation or injury.
• Hemolytic anemia: destruction of red blood cells.

When prescribing Metamizole, clinicians should consider several safety measures to minimize risk.

• Assess blood counts: monitor complete blood count regularly to detect agranulocytosis early.
• Evaluate allergy history: avoid use in patients with known hypersensitivity to pyrazolones.
• Use caution in renal impairment: adjust therapy as renal function declines.
• Avoid concomitant myelosuppressive drugs: increased risk of bone‑marrow suppression.
• Limit duration: use the lowest effective dose for the shortest necessary period.
• Store at ambient temperature: keep below 25 °C in the original container, protected from moisture.

Metamizole can interact with other medicines, altering efficacy or safety.

Major Interactions (Avoid)

• Anticoagulants (e.g., warfarin): increased bleeding risk due to platelet function inhibition.
• Methotrexate: enhanced toxicity through reduced renal clearance.

Moderate Interactions (Monitor Closely)

• Cyclosporine: possible increase in nephrotoxicity.
• Lithium: may raise serum lithium levels.
• SSRIs or SNRIs: heightened risk of serotonin syndrome.
• ACE inhibitors: potential for additive hypotensive effect.