In the pharmaceutical industry, the combination of Rifampicin (150 mg) and Isoniazid (75 mg) is a cornerstone Fixed-Dose Combination (FDC).
As a pharmacist and manufacturer, I classify this as the “Maintenance Phase” (or Continuation Phase) workhorse. After the initial intensive attack on Tuberculosis (TB), this $2\text{-}in\text{-}1$ ratio is used to ensure the complete eradication of remaining bacteria while significantly reducing “pill burden”—the primary factor in preventing the development of Multi-Drug Resistant TB (MDR-TB).
Primary Clinical Uses
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Pulmonary Tuberculosis: Used during the continuation phase of treatment (typically months 3 through 6) to eliminate “persister” bacilli.
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Extra-pulmonary Tuberculosis: Treatment of TB located in the bones, lymph nodes, or central nervous system.
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Latent TB Infection (LTBI): Often used in high-risk patients (such as those with HIV or household contacts of active TB cases) as preventive therapy to stop the infection from becoming active.
Dual Mechanism of Action: The Synergistic Attack
These two APIs attack Mycobacterium tuberculosis through entirely different pathways, ensuring that the bacteria cannot easily develop resistance.
Isoniazid (INH): The Cell Wall Destroyer
Action: It inhibits the synthesis of mycolic acids, which are unique and essential components of the mycobacterial cell wall.
Result: Without this waxy protective layer, the bacteria become fragile and die. It is highly effective against rapidly dividing bacilli.
Rifampicin: The Genetic Silencer
Action: It inhibits bacterial DNA-dependent RNA polymerase.
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Result: This prevents the bacteria from transcribing DNA into RNA, effectively stopping them from making the proteins necessary for survival. It is a powerful “sterilizing agent” that kills slow-growing or semi-dormant bacteria.
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The Manufacturer’s Perspective: Technical & Export
From a production and global trade standpoint at your WHO-GMP facility in Mumbai, this FDC is a high-volume essential:
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Rifampicin Stability: Rifampicin is notoriously sensitive to moisture and can act as a catalyst for the degradation of Isoniazid if the formulation isn’t optimized. At our facility, we prioritize Alu-Alu blister packaging to provide a total moisture barrier, ensuring a 36-month shelf life.
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The “Orange Effect” (Technical Transparency): As a pharmacist, your digital product literature should note that Rifampicin causes a harmless orange-red discoloration of urine, sweat, and tears. Including this detail in your B2B dossiers builds trust and professional recognition.
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Bioavailability (BA) Challenges: Achieving bioequivalence for Rifampicin in a combination tablet is technically demanding. Our Mumbai facility utilizes precise particle size distribution to ensure your export version matches the absorption rate of the innovator product.
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NGO & Government Tenders: This combination is a staple for the Global Fund and Stop TB Partnership. We provide full CTD/eCTD Dossiers to help your firm bid for these large-scale international contracts.