ISONIAZID = H oral

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    Last updated: June 2021

     

    Prescription under medical supervision

     

    Therapeutic action

    • First line antituberculosis antibacterial (bactericidal activity)

    Indications

    • Tuberculosis, in combination with other antituberculosis antibacterials
    • Latent tuberculosis, as monotherapy or in combination with rifampicin or rifapentine

    Forms and strengths

    • 100 mg and 300 mg tablets
    • 50 mg and 100 mg dispersible tablets

    Dosage

    Tuberculosis, latent tuberculosis as monotherapy or in combination with daily rifampicin

    • Child under 30 kg: 10 mg/kg (7 to 15 mg/kg) once daily, on an empty stomach
    • Child 30 kg and over and adult: 5 mg/kg (4 to 6 mg/kg) once daily, on an empty stomach

    Do not exceed 300 mg daily.

     

    Latent tuberculosis in combination with weekly rifapentine

    • Child under 30 kg and over 2 years: 20 to 30 mg/kg once weekly, on an empty stomach
    • Child 30 kg and over and adult: 900 mg once weekly, on an empty stomach

     

    Latent tuberculosis in combination with daily rifapentine

    • Child 13 years and over and adult: 300 mg once daily, on an empty stomach

    Duration

    • Tuberculosis and latent tuberculosis as monotherapy: according to protocol
    • Latent tuberculosis in combination with daily rifampicin or weekly rifapentine: 3 months
    • Latent tuberculosis in combination with daily rifapentine: 1 month

    Contra-indications, adverse effects, precautions

    • Do not administer to patients with severe hepatic impairment.
    • May cause:
      • peripheral neuropathy, especially in malnourished, alcoholic, diabetic, HIV-infected patients; pregnant and breast-feeding women and patients with renal impairment;
      • hepatotoxicity, especially in alcoholic patients or patients with chronic hepatic disease or receiving rifampicin, or over 35 years;
      • hypersensitivity reactions, psychotic reactions, seizures and depression.
    • Monitor liver function in patients with known hepatic disease.
    • If signs of hepatotoxicity (e.g. jaundice) develop, isoniazid should be discontinued until symptoms resolve.
    • Administer with caution and closely monitor patients taking phenytoin, carbamazepine, benzodiazepines (risk of toxicity), warfarin (risk of bleeding).
    • Administer pyridoxine (vitamin B6) in patients at risk of peripheral neuropathy (child: 5 to 10 mg once daily; adult: 10 mg once daily).
    • Pregnancy: no contra-indication. Administer pyridoxine to the mother (10 mg once daily).
    • Breast-feeding: no contra-indication;. Administer pyridoxine to the mother (10 mg once daily) and the infant (5 mg once daily).

    Remarks

    • For patients sensitive to first-line antituberculosis treatment, isoniazid is given as part of a fixed dose combination.
    • Also comes in fixed dose combination containing 300 mg of rifapentine/300 mg of isoniazid for the treatment of latent tuberculosis in children over 14 years and adults.

    Storage

     
    – 
     
    – Below 25 °C 
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