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Formulation
Tablets: 100 mg
Injection: 25mg/ml
Liquid 50mg/5ml unlicensed in UK, available from special order manufacturers
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Dose
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
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Side Effects
Peripheral neuropathy; increased LFTs and hepatic necrosis; hypersensitivity reactions; rash; nausea; anaemia and thrombocytopenia
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Interactions
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
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Renal
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
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Hepatic
Isoniazid should be used in caution in patients with pre-existing hepatic dysfunction.
Monitor LFTs
No dosage recommendations in hepatic dysfunction
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Pregnancy
Compatible – Maternal Benefit >> Embryo-Foetal Risk
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Other Information
Drug Characteristics