What is rifampicin 150mg isoniazid 75mg tablets used for?
In the pharmaceutical industry, the combination of Rifampicin (150 mg) and Isoniazid (75 mg) is a core Fixed-Dose Combination (FDC) used in the treatment of Tuberculosis (TB). As a pharmacist and manufacturer, I view this as a “Synergistic Sterilizing System”—it combines the two most powerful first-line antitubercular drugs to ensure both rapid bacterial kill and the prevention of drug resistance.
At your WHO-GMP facility in Mumbai, this 2-FDC is a high-volume “Essential Medicine” SKU. It is primarily used during the Continuation Phase of TB treatment (after the initial intensive phase) to ensure the complete eradication of remaining bacilli.
Therapeutic Profile: Clinical Applications
This specific ratio (150/75) is designed for adult maintenance therapy and pediatric weight-based dosing.
| Indication | Clinical Context | Technical Rationale |
| Pulmonary TB | Continuation Phase | Taken daily or intermittently for 4–7 months after the 2-month intensive phase. |
| Latent TB (LTBI) | Preventative Therapy | Used to prevent active disease in high-risk individuals (e.g., HIV+ or household contacts). |
| Extra-Pulmonary TB | Extended Treatment | Used for TB of the lymph nodes, bones, or kidneys as part of a long-term regimen. |
| Pediatric TB | Weight-Based Dosing | The 150/75 ratio allows for flexible dosing in children based on WHO weight bands. |
Mechanism: Dual-Target Bacterial Inhibition
This FDC attacks Mycobacterium tuberculosis at two critical structural levels:
Rifampicin (RNA Blockade): It inhibits the bacterial DNA-dependent RNA polymerase. By stopping the bacteria from transcribing DNA into RNA, it effectively halts all protein synthesis, killing both active and semi-dormant bacteria.
Isoniazid (Cell Wall Blockade): It is a prodrug that inhibits the synthesis of mycolic acids, which are essential components of the mycobacterial cell wall. This leads to the death of rapidly dividing bacteria.
The FDC Advantage: Technically, using these two together in a single tablet prevents “monotherapy,” which is the leading cause of Multi-Drug Resistant TB (MDR-TB).
The Pharmacist’s “Technical Warning”
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The “Empty Stomach” Mandate: As a pharmacist, I must emphasize that this tablet must be taken 1 hour before or 2 hours after meals. Food significantly reduces the absorption (bioavailability) of Rifampicin.
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The “Orange Signal”: Patients must be warned that Rifampicin will turn urine, sweat, tears, and saliva an orange-red color. This is harmless but can stain contact lenses.
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Hepatotoxicity Risk: Both drugs are processed by the liver. Patients must avoid alcohol and report any signs of jaundice (yellowing of eyes) or persistent nausea immediately.
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Peripheral Neuropathy: Isoniazid can cause “pins and needles” sensations. I highly recommend co-prescribing Pyridoxine (Vitamin $B_6$) to protect the nerves.
The Manufacturer’s Perspective: Technical & Export
From a production and B2B standpoint at your facility in Mumbai:
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The “Compliance Anchor” USP: On your digital platforms, highlight the bioequivalence of your FDC. Proving that your 2-in-1 tablet delivers the same plasma levels as individual drugs is vital for international NGO tenders (like The Global Fund).
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Stability for Export: Rifampicin is highly sensitive to moisture and light. Utilizing Alu-Alu blister packaging is the strict industry standard for ensuring a 36-month shelf life in Zone IVb tropical regions.
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Dossier Support: We provide full WHO-standard CTD/eCTD Dossiers for the 150/75 mg strength, including stability data specifically for tropical climates, to support your firm’s registration in global TB programs.