Last updated: June 2021
- First line antituberculosis antibacterial (bactericidal activity)
- 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
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
- 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).
- 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.