Description
Mechanism of Action
Isoniazid is active against M tuberculosis, M bovis and some strains of M kansasii. One of its main mechanisms appears to be mycolic acid synthesis inhibition resulting in loss of acid-fastness and bacterial cell wall disruption.
Absorption: Absorbed readily from the GIT (oral) and after parenteral admin (IM); peak plasma concentrations after 1-2 hr (oral). Rate and extent may be reduced by the presence of food.
Distribution: Body tissues and fluids, CSF, crosses the placenta and enters breast milk.
Metabolism: Hepatic and enteral; acetylation by N-acetyltransferase to acetylisoniazid followed by hydrolysis to isonicotinic acid and monoacetylhydrazine, then conjugated with glycine to isonicotinyl glycine and monoacetylhydrazine is further acetylated to diacetylhydrazine.
Excretion: Via urine (as metabolites), via faeces (small amounts); 1-6 hr (elimination half-life), removed by dialysis.
MIMS Class
Anti-TB Agents
ATC Classification
J04AC01 – isoniazid; Belongs to the class of hydrazides. Used in the systemic treatment of tuberculosis.;
