Natrijev Metamizolat Kalceks (Metamizole Sodium Monohydrate)

Metamizole sodium is used for the management of pain and fever across several clinical situations.

• Pain: Provides rapid analgesia for acute moderate to severe pain, often when other agents are insufficient.
• Fever: Effectively lowers elevated body temperature in patients requiring antipyretic therapy.
• Post‑operative pain: Controls surgical pain during the immediate postoperative period, facilitating early mobilization.

• Metamizole sodium inhibits cyclooxygenase enzymes, decreasing prostaglandin synthesis, and simultaneously modulates endogenous opioid pathways. This dual action reduces peripheral and central sensitisation, producing analgesic and antipyretic effects without significant opioid receptor activation. It also interferes with the release of inflammatory mediators such as bradykinin and histamine, contributing to its fever‑lowering properties.

Metamizole sodium may be associated with a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Injection site pain: Local discomfort at the site of administration.
• Nausea: Mild to moderate feeling of queasiness.
• Dizziness: Transient sensation of light‑headedness.
• Sweating: Increased perspiration without exertion.
• Hypotension: Temporary drop in blood pressure.

Serious or Rare Side Effects

• Agranulocytosis: Severe reduction in white blood cells, potentially life‑threatening.
• Severe allergic reactions: Including anaphylaxis and Stevens‑Johnson syndrome.
• Renal failure: Impaired kidney function in susceptible individuals.

When using Metamizole sodium, several precautions should be observed to minimise risk.

• Blood count monitoring: Perform baseline and periodic complete blood counts to detect agranulocytosis early.
• Allergy assessment: Evaluate for known hypersensitivity to pyrazolones before administration.
• Renal/hepatic function: Use with caution in patients with impaired kidney or liver function.
• Concomitant myelosuppressive therapy: Avoid combining with other drugs that suppress bone marrow.
• Store at 2-8°C: Keep refrigerated, protect from light, do not freeze or shake.

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

Major Interactions (Avoid)

• Myelosuppressive agents: Concurrent use may markedly increase risk of severe blood dyscrasias.
• Other pyrazolones or drugs causing agranulocytosis: Combined exposure heightens risk of life‑threatening neutropenia.
• Anticoagulants: May potentiate bleeding tendency due to platelet function inhibition.

Moderate Interactions (Monitor Closely)

• Diuretics: May enhance hypotensive effects; monitor blood pressure.
• CYP450 substrates: Metamizole may induce certain enzymes, potentially altering plasma levels of co‑administered drugs.