Isoniazid

Antituberculosis Preps · Isonicotinic acid derivative

Indications

Treatment of tuberculosis in conjunction with other anti-tuberculosis drugs.

Dosage

The suggested dosage according to weight: Adults: 5-10 mg/kg body weight. Infants & Children: 10-20 mg/kg body weight. The suggested dosage according to age: Below 6 mth, 25 mg twice a day; upto 1 yr, 50 mg twice a day; 1-3 yr, 50 mg thrice a day; 3-12 yr, 100 mg twice a day; above 12 yr, 100 mg thrice a day.

Adverse Effects

Peripheral neuropathy. Nausea, vomiting, epigastric distress. Elevated SGOT, SGPT, SGOPT. Agranulocytosis. Fever, skin eruptions, pyridoxine deficiency, dry mouth, optic neuritis, convulsions, psychosis, hypersensitivity reactions, blood disorders, hepatitis, SLE like syndrome, hyperglycaemia, gynaecomastia.

Risk Factor (Pregnancy/Lactation)

Pregnancy: Risk cannot be ruled out. Lactation: Caution advised or effect undetermined. Contraindications: Patients with previous isoniazid associated hepatic injury or other severe adverse reactions with isoniazid. Precautions: Patients with active chronic liver disease or severe renal dysfunction. Isoniazid crosses the placental barrier and passes into maternal breast milk, observe neonates, breast fed infants of isoniazid treated mothers for any evidence of adverse effects. History of psychosis, alcoholism, porphyria, diabetes, HIV infection.

Interactions

Corticosteroid, benzodiazepines, rifampicin, anticonvulsants, diazepam, theophylline, stavudine, cycloserine.

Advice to Patient

Take 1 hour before or 2 hours after meals. To prevent abdominal discomfort, take with meals. Contact prescriber if there is fever, decreased appetite, numbness or tingling in hands or feet, loss of sensation, unusual weakness, nausea, fatigue or vomiting, changes in urinary pattern, dark coloured urine, change in colour of stool, yellowing of skin or eyes, changes in vision. Avoid alcohol intake, foods containing tyramine (such as broad beans, aged cheese, dry sausage, liver pate, preserved meats or sausages, fish, soybean, protein supplements, red wine), histamine-containing foods (such as tuna, skipjack, and other tropical fish) and increased intake of magnesium, folate, niacin. Frequent eye examinations and medical check-ups are required to monitor progress of condition and effectiveness of drug.

Pharmacokinetics

Absorption: Oral, IM: Rapid and complete; food reduces rate and extent of absorption. Metabolism: Hepatic. Half-life: May be prolonged in patients with impaired hepatic function or severe renal impairment. Fast acetylators: 30-100 mins. Slow acetylators: 2-5 hrs. Time to peak, serum: 1-2 hrs. Excretion: Urine (75%-95%). Small amounts excreted in faeces and saliva.

Brands with this active ingredient

Compiled by Healify Pharmacy from published drug references. How we compile it →

Always consult a pharmacist or doctor.