Nicozid (Isoniazid)

Isoniazid is an antitubercular drug that targets Mycobacterium tuberculosis infection and related preventive strategies.

• Tuberculosis (active disease): forms part of combination therapy to eradicate Mycobacterium tuberculosis.
• Latent TB infection: used to prevent progression to active disease in individuals with a positive tuberculin test.
• Post‑exposure prophylaxis: administered to recent contacts of confirmed TB cases to reduce infection risk.

• Isoniazid inhibits the synthesis of mycolic acids, essential components of the mycobacterial cell wall, by targeting the enzyme InhA after activation by the bacterial catalase‑peroxidase KatG. This disruption compromises cell wall integrity, leading to bacterial death, particularly in actively replicating Mycobacterium tuberculosis.

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

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Loss of appetite: reduced desire to eat.
• Peripheral neuropathy: tingling or numbness, especially in the extremities.
• Rash or mild skin eruption.
• Fever or flu‑like symptoms.
• Elevated liver enzymes without clinical symptoms.

Serious or Rare Side Effects

• Hepatotoxicity: severe liver injury, jaundice, or hepatitis.
• Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Severe allergic reactions: anaphylaxis, angioedema.
• Blood dyscrasias: agranulocytosis, thrombocytopenia.
• Seizures: particularly in overdose or with pre‑existing CNS disease.
• Peripheral neuropathy requiring medical intervention.

Use of Nicozid requires careful monitoring and patient education.

• Liver function monitoring: obtain baseline and periodic liver enzyme tests.
• Neuropathy prevention: co‑administer pyridoxine (vitamin B6) to reduce peripheral nerve damage.
• Alcohol consumption: advise avoidance or limitation to lower hepatotoxic risk.
• Pregnancy assessment: evaluate risk‑benefit ratio before prescribing.
• Drug interaction review: check for concomitant hepatotoxic or enzyme‑inducing agents.
• Store at ambient temperature: keep in original container, protect from moisture and light.

Isoniazid can interact with several medicines, altering efficacy or safety.

Major Interactions (Avoid)

• Rifampicin: combined use increases risk of liver injury.
• Phenytoin: may reduce isoniazid plasma concentrations.
• Alcohol: synergistic hepatotoxic effect.

Moderate Interactions (Monitor Closely)

• Acetylator status: fast acetylators clear the drug more quickly, affecting effectiveness.
• Carbamazepine: additive hepatotoxic potential, requires liver function monitoring.
• Sulfonamides: may increase hypersensitivity reactions when used together.