Isoniazid

Indication

Isoniazid is a primary drug for tuberculosis (TB). In active TB, it is used together with other drugs. For prophylaxis, it is used alone in children. It is used in treatment of susce­ptible tuberculosis infections, extrapulmonary lesions, meningitis, genito-urinary diseases and vulgaris.

Dosage and Administration

Adult: Usually 200 - 300 mg single dose daily for 6 months (Supplemented by pyridoxine)

Children: 10 - 15 mg/kg/day for 6 months (Maximum 300 mg) or as directed by the physician.

Composition

Each tablet contains:

Isoniazid B.P ... 100 mg.

Description

Isoniazid is a monoamine-oxidase inhibitor. Chemically, it is pyridine-4-carbohydrazide. Its molecular formula is C6H7Np and its molecular weight is 137.1.

Clinical Pharmacology

Isoniazid is a monoamine-oxidase inhibitor (MAOI) and is effective as a primary antituberculous chemotherapeutic agent. The mechanism of action is unknown but it may include the inhibition of mycolic acid synthesis resulting in distribution of the bacterial cell wall.

Pharmacokinetics

Absorption is rapid and complete, and the rate can be slowed with food. The absolute oral bioavailability is about 90%. Peak serum concentration is about 1 - 2 hours. It is distributed into all body tissues and fluids including CSF, crosses the placenta and enters the breast milk. Plasma protein bin...read more

Contraindication

Contraindicated in patients with hypersensitivity to isoniazid or any component of the formulation.

Contraindicated in patients with acute liver disease, previous history of hepatic damage during isoniazid therapy.

Precaution

lsoniazid should not be given to patients who have experienced severe adverse reactions to it including drug-induced liver disease. Care should be taken in giving isoniazid to patients suffering from conclusive disorders, diabetes mellitus, chronic alcoholism or impaired liver or kidney function or ...read more

Adverse Effects

Hypersensitivity: fever, skin rashes, hepatitis, vasculitis, systemic lupus erythematosus, neuritis.

Central nervous system: insomnia, restlessness, convulsion, dizziness, mental disturbances, seizures.

Gastrointestinal: Loss of appetite, nausea, vomiting, abdominal pain.

Drug Interaction

There may be an increased risk of liver damage in patients receiving rifampicin and isoniazid but liver enzymes are generally raised only transiently. Isoniazid enhances the effect of phenytoin, carbamazepines, oral anticoagulants and may also inhibit the metabolism ofprimidone, there may be increas...read more

Storage

Store below 30°C in cool, dry place. Protect from light and moisture. Keep out of reach and sight of children.

Presentations

10 x 10's Blisters.