Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2019 Publisher: RPH Pharmaceuticals AB, Lagervägen 7, 136 50 Haninge, Sweden
Isoniazid has no significant antibacterial action against any micro-organisms except the mycobacteria; against mycobacterium tuberculosis it is bacteriostatic in extremely low concentrations.
Isoniazid is used mainly in the treatment of pulmonary tuberculosis but it appears to be effective also in the treatment of extrapulmonary lesions, including meningitis and genito-urinary disease.
Readily and completely absorbed after oral administration.
Readily diffuses into all tissues and fluids including the cerebrospinal fluid. Isoniazid is retained in the skin and in infected tissue; it crosses the placenta and is secreted in the milk of lactating mothers.
Isoniazid does not appear to be bound in the blood.
Plasma elimination half-life, in rapid acetylators about 1.2 hours and in slow acetylators about 3.5 hours.
Acetylation, hydrolysis and glycine conjugation, hydrazone formation, and n-methylation; acetylation is polymorphic and two groups of acetylators have been identified, rapid and slow acetylators. The rate of hydrolysis is more rapid in the rapid acetylators than in the slow ones. The metabolites formed include acetyl isoniazid, isonicotinic acid, isonicotinuric acid, isonicotinoyl-hydrazones of pyruvic and glutaric acids, and n-methylisoniazid.
Over 90% of a dose is excreted in the urine in 24 hours, most being excreted in the first 12 hours, 4-32% is unchanged, but no more than 10% of a dose is excreted in the faeces.
Not applicable since isoniazid tablets have been used in clinical practice for many years and its effects in man are well known.
© All content on this website, including data entry, data processing, decision support tools, "RxReasoner" logo and graphics, is the intellectual property of RxReasoner and is protected by copyright laws. Unauthorized reproduction or distribution of any part of this content without explicit written permission from RxReasoner is strictly prohibited. Any third-party content used on this site is acknowledged and utilized under fair use principles.
