Tablets: 100 mg

Injection: 25mg/ml

Liquid 50mg/5ml unlicensed in UK, available from special order manufacturers

DMAC: 300 mg orally once a day, as part of a combination regimen

Or

15mg/kg (max 900 mg) orally twice or three times a week for D.O.T regimens

Peripheral neuropathy; increased LFTs and hepatic necrosis; hypersensitivity reactions; rash; nausea; anaemia and thrombocytopenia

Antacids reduce absorption; increased CNS toxicity with cycloserine; enhanced phenytoin and carbamazepine effect; additive hepatic toxicity with carbamazepine; metabolism of ketoconazole increased

Additive toxicity with other drugs causing peripheral neuropathy e.g. stavudine, dapsone

GFR (ml/min)

20–50 Dose as in normal renal function

10–20 Dose as in normal renal function

<10 100–200 mg daily suggested

Alternative dosing from Renal Handbook

<10 200-300mg

Patients with GFR < 10 ml/minute and slow acetylator status might require a dose reduction of about 100mg to maintain trough plasma levels at less than 1 mcg/ml

Isoniazid should be used in caution in patients with pre-existing hepatic dysfunction.

Monitor LFTs

No dosage recommendations in hepatic dysfunction

Compatible – Maternal Benefit >> Embryo-Foetal Risk