Rimactazid
Generic Name
Rifampicin and Isoniazid
Manufacturer
Novartis
Country
Switzerland (originator)
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Price Details
Current market pricing information
| Variant | Unit Price | Strip Price |
|---|---|---|
| rimactazid 450 mg tablet | ৳ 11.74 | ৳ 117.40 |
Description
Overview of the medicine
Rimactazid 450 mg Tablet is a fixed-dose combination medicine used in the treatment of tuberculosis. It contains Rifampicin and Isoniazid, which are potent anti-tuberculosis agents.
Uses & Indications
Dosage
Adults
Usually 2 tablets (Rifampicin 600 mg + Isoniazid 300 mg) once daily, or as per national TB guidelines based on patient weight.
Elderly
Same as adults, but monitor for hepatic function and potential drug interactions more closely.
Renal_impairment
No dose adjustment generally required for rifampicin. Isoniazid dose may need adjustment in severe renal impairment (CrCl < 10 mL/min). Consult physician.
How to Take
Take on an empty stomach, at least 30 minutes before food or 2 hours after food, with water. Administer once daily. Do not crush or chew.
Mechanism of Action
Rifampicin inhibits bacterial RNA synthesis by binding to DNA-dependent RNA polymerase. Isoniazid inhibits mycolic acid synthesis, an essential component of the mycobacterial cell wall. Together, they have synergistic bactericidal activity against Mycobacterium tuberculosis.
Pharmacokinetics
Onset
Clinical improvement usually observed within weeks of treatment initiation.
Excretion
Rifampicin: Primarily via bile into feces, some renal excretion. Isoniazid: Primarily via urine.
Half life
Rifampicin: 2-5 hours (decreases with repeated doses due to auto-induction). Isoniazid: 1-4 hours (varies with acetylator status).
Absorption
Both rifampicin and isoniazid are well absorbed orally. Food may delay or reduce absorption of rifampicin.
Metabolism
Rifampicin: Hepatic metabolism (deacetylation), enterohepatic recirculation. Isoniazid: Hepatic metabolism (acetylation) primarily by N-acetyltransferase 2 (NAT2).
Side Effects
Contraindications
- Hypersensitivity to rifamycins or isoniazid.
- Acute liver disease, drug-induced hepatitis, or history of severe adverse reactions to these drugs.
Drug Interactions
Alcohol
Increases risk of hepatotoxicity with isoniazid.
Oral Contraceptives
Rifampicin is a potent enzyme inducer, significantly reducing the efficacy of oral contraceptives. Use alternative birth control.
Phenytoin, Carbamazepine
Decreased levels of anticonvulsants.
Anticoagulants (Warfarin)
Rifampicin may decrease warfarin levels, requiring dose adjustment and close INR monitoring.
Ketoconazole, Itraconazole
Reduced antifungal levels due to rifampicin.
Antiretroviral drugs (Protease inhibitors, NNRTIs)
Significant interactions, often requiring dose adjustments or alternative regimens due to enzyme induction by rifampicin.
Storage
Store in a cool, dry place below 30°C. Protect from light and moisture. Keep out of reach of children.
Overdose
Symptoms include nausea, vomiting, abdominal pain, drowsiness, lethargy, orange-red discoloration of skin/fluids (rifampicin), peripheral neuropathy, seizures, metabolic acidosis (isoniazid). Treatment is supportive, including gastric lavage, activated charcoal, and pyridoxine for isoniazid overdose.
Pregnancy & Lactation
Use in pregnancy only if clearly needed and benefits outweigh risks, as both drugs cross the placenta. Isoniazid causes peripheral neuropathy in some neonates, advise pyridoxine supplementation for mother. Both drugs are excreted in breast milk; advise against breastfeeding or use with caution after consulting physician.
Side Effects
Contraindications
- Hypersensitivity to rifamycins or isoniazid.
- Acute liver disease, drug-induced hepatitis, or history of severe adverse reactions to these drugs.
Drug Interactions
Alcohol
Increases risk of hepatotoxicity with isoniazid.
Oral Contraceptives
Rifampicin is a potent enzyme inducer, significantly reducing the efficacy of oral contraceptives. Use alternative birth control.
Phenytoin, Carbamazepine
Decreased levels of anticonvulsants.
Anticoagulants (Warfarin)
Rifampicin may decrease warfarin levels, requiring dose adjustment and close INR monitoring.
Ketoconazole, Itraconazole
Reduced antifungal levels due to rifampicin.
Antiretroviral drugs (Protease inhibitors, NNRTIs)
Significant interactions, often requiring dose adjustments or alternative regimens due to enzyme induction by rifampicin.
Storage
Store in a cool, dry place below 30°C. Protect from light and moisture. Keep out of reach of children.
Overdose
Symptoms include nausea, vomiting, abdominal pain, drowsiness, lethargy, orange-red discoloration of skin/fluids (rifampicin), peripheral neuropathy, seizures, metabolic acidosis (isoniazid). Treatment is supportive, including gastric lavage, activated charcoal, and pyridoxine for isoniazid overdose.
Pregnancy & Lactation
Use in pregnancy only if clearly needed and benefits outweigh risks, as both drugs cross the placenta. Isoniazid causes peripheral neuropathy in some neonates, advise pyridoxine supplementation for mother. Both drugs are excreted in breast milk; advise against breastfeeding or use with caution after consulting physician.
Frequently Asked Questions
Common questions about this medicine
Pack Sizes
Shelf Life
Typically 2-3 years from manufacturing date.
Availability
Hospitals, Pharmacies
Approval Status
Approved
Patent Status
Off-patent
WHO Essential Medicine
YesClinical Trials
Numerous clinical trials have established the efficacy and safety of Rifampicin and Isoniazid combinations for tuberculosis treatment, forming the cornerstone of global TB control programs.
Lab Monitoring
- Liver function tests (ALT, AST, bilirubin) at baseline and monthly.
- Complete blood count (CBC).
- Renal function tests (creatinine).
- For isoniazid, monitor for symptoms of peripheral neuropathy and consider pyridoxine supplementation.
Doctor Notes
- Emphasize strict adherence to the regimen to prevent resistance.
- Monitor liver function closely, especially in patients with pre-existing liver disease or those on other hepatotoxic drugs.
- Counsel patients on potential for red-orange discoloration of bodily fluids.
Patient Guidelines
- Complete the full course of treatment even if you feel better. Do not stop without consulting your doctor.
- Report any yellowing of skin/eyes, dark urine, or unusual tiredness immediately.
- Take with pyridoxine (Vitamin B6) to prevent peripheral neuropathy from isoniazid.
Missed Dose Advice
If a dose is missed, take it as soon as you remember, unless it is almost time for your next dose. Do not take a double dose to make up for a missed one. Continue your regular dosing schedule.
Driving Precautions
May cause dizziness or visual disturbances in some individuals. If affected, avoid driving or operating heavy machinery.
Lifestyle Advice
- Avoid alcohol due to increased risk of liver damage.
- Maintain a balanced diet.
- Adherence to treatment is crucial for successful outcomes and preventing drug resistance.
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