Generic
Isoniazid + Rifampicin
12 brands available in the market
At a glance
Isoniazid + Rifampicin combination is used for the continuation phase treatment of tuberculosis (TB).
Description
Isoniazid + Rifampicin is a combination of two antitubercular drugs that stop the growth of mycobacteria. Rifampicin inactivates a bacterial enzyme (RNA-polymerase) required by TB bacteria to make essential proteins and reproduce. Isoniazid prevents these bacteria from forming their own protective covering. Together, they kill the bacteria and eradicate the infection.
Indications
- Tuberculosis (TB) - continuation phase treatment
Pharmacological class
Antimycobacterial (Combination)
Pharmacology
Rifampicin and isoniazid are active bactericidal anti-TB drugs which are particularly active against the rapidly growing extracellular organisms and also have bactericidal activity intracellularly. Rifampicin inhibits DNA-dependent RNA polymerase activity in susceptible cells. Isoniazid acts against actively growing tubercle bacilli.
Mechanism of action
Isoniazid prevents bacterial protective covering formation; Rifampicin inactivates RNA-polymerase.
Dosage
Adult Dose (Oral):
- Body weight <50 kg: 3 tablet of 150/100 once daily OR 1 tablet of 450/300 once daily
- Body weight >50 kg: 2 tablet of 300/150 once daily
- Hepatic impairment: Max: 8 mg/kg daily
Child Dose: Dose determined by physician based on weight
Administration
Take on empty stomach; swallow whole; do not chew, crush or break; take at the same time every day; avoid tyramine-rich foods (cheese, smoked fish, meats, some beers); maintain at least 2 hours gap with antacids.
Missed dose
If you miss a dose, take it as soon as possible; if it is almost time for your next dose, skip the missed dose and go back to regular schedule; do not double the dose.
Drug interactions
Drug Interactions:
- Rifampicin reduces effectiveness of hormonal contraceptives
- Reduced absorption with antacids
- Interactions with anticoagulants, anticonvulsants, corticosteroids, digoxin, oral hypoglycemic agents
- Isoniazid may inhibit metabolism of anticonvulsants, benzodiazepines, theophylline, warfarin
Food interactions
Food Interactions: Consuming alcohol while taking this medicine may cause flushing, increased heart beat, nausea, thirst, chest pain and low blood pressure (Disulfiram reaction); avoid tyramine-rich foods.
Contraindications
Contraindications:
- Known or suspected hypersensitivity to rifamycins and/or INH
- History of drug-induced hepatitis
- Acute liver diseases
- Peripheral neuritis
Side effects
Common Side Effects:
- Dark colored urine (normal and harmless)
- Rash
- Vomiting
- Jaundice
- Fever
- Increased liver enzymes
- Nausea
- Peripheral neuropathy (tingling and numbness of feet and hand)
Others: Tiredness, drowsiness, headache, dizziness, ataxia, mental confusion, muscular weakness, visual disturbances, leukopenia, thrombocytopenia
Use in pregnancy
Use in Pregnancy: May be unsafe; animal studies have shown harmful effects; doctor will weigh benefits and risks.
Pregnancy Category: C — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Safe during breastfeeding; does not pass into breastmilk in significant amount and is not harmful to baby.
Precautions & warnings
Precautions:
- Isoniazid + Rifampicin may affect your ability to drive (seizures, mental problems, optic neuritis)
- Regular monitoring of liver function tests advised
- Avoid alcohol (may cause disulfiram reaction)
- Inform doctor if signs of jaundice (yellowing of eyes or skin, dark urine, stomach pain)
- Caution in kidney and liver disease
- Hormonal contraceptives may be less effective (use additional contraceptive methods)
Pediatric use
Pediatric dose determined by physician based on weight.
Geriatric use
No specific data for elderly; however caution advised.
Renal / hepatic impairment
Renal Impairment: Caution in kidney disease; dose adjustment may be needed.
Hepatic Impairment: Caution in liver disease; dose adjustment may be needed; not recommended in severe liver disease; regular monitoring of liver function tests advised.
Overdose effects
Overdose: Nausea, vomiting, abdominal pain, dizziness, confusion, liver toxicity; seek emergency medical attention; gastric lavage and activated charcoal; symptomatic treatment.
Therapeutic class
Anti-tubercular antibiotics
Storage conditions
Keep below 30°C temperature, away from light & moisture; keep out of reach of children.
Chemical structure
Isoniazid + Rifampicin