Generic
Isoniazid + Rifampicin
10 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
Therapeutic class
Anti-tubercular antibiotics
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.
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
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)
Contraindications
Contraindications:
- Known or suspected hypersensitivity to rifamycins and/or INH
- History of drug-induced hepatitis
- Acute liver diseases
- Peripheral neuritis
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.
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.
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.
Storage conditions
Keep below 30°C temperature, away from light & moisture; keep out of reach of children.
Chemical structure
Isoniazid + Rifampicin