Isoniazid (isonicotinylhydrazine) is an antibacterial prodrug which is metabolized in vivo to isonicotinic acyl-NADH complex which blocks the synthesis of mycolic acid, required for mycobacterial cell walls.
Side-effects associated with toxicity with this drug are associated with excessive cytochrome P450 induction and include acute renal injury, seizures, myocarditis and metabolic acidosis. The LD50 of this drug in dogs is 150 mg/kg.
Recommended dose rate is 10 - 20 mg/kg given orally once daily every 24 hrs (max < 100mg total/day).
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