Curazid Forte

Isoniazid, pyridoxine HCl.

Each 5 mL contains isoniazid 200 mg and pyridoxine HCl (vitamin B6) 10 mg.

Microbiology: Isoniazid is highly active against Mycobacterium tuberculosis which it inhibits in vitro at concentrations of 0.02-0.2 mcg/mL. Isoniazid may have activity against some strains of the mycobacteria including M. kansasii.
Although it is rapidly bactericidal against actively dividing M. tuberculosis, it is considered to be only bacteriostatic against semi-dormant organisms and has less sterilizing activity than rifampicin or pyrazinamide. Pharmacokinetics: Peak concentrations of about 3-8 mcg/mL appear in blood 1-2 hrs after a fasting dose of 300 mg orally. The rate and extent of absorption of isoniazid is reduced by food. Isoniazid s not considered to be bound appreciably to plasma proteins and diffuses into all body tissues and fluids, including breast milk.
The plasma t_½ for isoniazid ranges from about 1-6 hrs, those who are fast acetylators having shorter t_½. The primary metabolic route is the acetylation of isoniazid to acetylisoniazid by N-acetyltransferase found in the liver and small intestines. Acetylisoniazid is then hydrolyzed to isonicotinic acid and monoacetylhydrazine; isonicotinic acid is conjugated with glycine to isonicotinyl glycine (isonicotinuric acid) and monoacetylhydrazine is further acetylated to diacetylhydrazine. Some unmetabolized isoniazid is conjugated to hydrazones. The metabolites of isoniazid have no tuberculostatic activity and apart from possibly monoacetylhydrazine, they are also less toxic.
In patients with normal renal function, over 75% of a dose appears in the urine in 24 hrs mainly as metabolites. Small amounts of drug are also excreted in the feces. Isoniazid is removed by dialysis.

Primary treatment of pulmonary and extrapulmonary tuberculosis. It is administered with other antituberculous drugs usually including rifampicin and pyrazinamide. Prophylaxis of tuberculosis in high risk subjects. Isoniazid is given in the initial and continuation phase of short-course tuberculosis regimens.

Adults: Usual Dose: 300 mg daily orally on an empty stomach.
Children: 5 mg/kg body weight daily. Maximum Dose: 300 mg daily.
Intermittent Therapy: 10 mg/kg body weight 3 times weekly or 15 mg/kg body weight twice weekly. Maximum Dose: 900 mg.
Doses may need to be reduced in patients with hepatic impairment or moderate to severe renal impairment.
Tuberculosis Prophylaxis: Daily dose of 300 mg are given for at least 6 months and sometimes for up to 1 year.

Isoniazid should be administered with caution to patients with convulsive disorders, a history of psychosis or hepatic or renal dysfunction. Patients who are at risk of neuropathy or pyridoxine deficiency, including those who are diabetic, alcoholic, malnourished, uremic, pregnant or HIV-infected should receive pyridoxine usually in a dose of 10 mg daily, although some have suggested using up to 50 mg daily. If symptoms of hepatitis eg, malaise, fatigue, anorexia and nausea develop, isoniazid should be discontinued pending evaluation.
Liver function should be checked before treatment with isoniazid and special care should be taken in alcoholic patients or those with preexisting liver disease.

Isoniazid is generally well-tolerated at currently recommended doses. However, patients who are slow acetylators of isoniazid appear to have a higher incidence of some adverse effects. Also, patients whose nutrition is poor are at risk of peripheral neuritis which is one of the most common adverse effect of isoniazid. Other neurological adverse effects include psychotic reactions and convulsions. Pyridoxine may be given to prevent or treat these adverse effects. Optic neuritis has also been reported.
Hematological effects reported following use of isoniazid include various anemias, agranulocytosis, thrombocytopenia and eosinophilia.
Other adverse effects include nausea, vomiting, pellagra, purpura, hyperglycemia, lupus-like syndrome, urinary retention and gynecomastia.
Treatment of Adverse Effects: Pyridoxine HCl 10 mg daily has been recommended to prophylaxis of peripheral neuritis associated with isoniazid although some have suggested using up to 50 mg daily.

Store at temperatures not exceeding 30°C.

Anti-TB Agents

J04AC51 - isoniazid, combinations ; Belongs to the class of hydrazides. Used in the systemic treatment of tuberculosis.

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