In the pharmaceutical industry, the combination of Isoniazid (INH) and Pyridoxine Hydrochloride (Vitamin B6) is the gold standard for both the treatment and prophylaxis of Tuberculosis (TB). As a pharmacist and manufacturer, I view this as a “preventative combination”: Isoniazid kills the bacteria, while Pyridoxine prevents the most common neurological side effect of the treatment.
Primary Clinical Uses
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Active Tuberculosis: Used as a core component of the “RIPE” regimen (Rifampicin, Isoniazid, Pyrazinamide, and Ethambutol) for the treatment of Mycobacterium tuberculosis.
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Latent TB Infection (LTBI): Often used as monotherapy for 6–9 months to prevent a dormant infection from becoming active.
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TB Prophylaxis: Prescribed for individuals in close contact with TB patients or immunocompromised patients (such as those with HIV) who are at high risk of infection.
The Dual Mechanism: Action vs. Protection
1. Isoniazid (The Bactericidal Agent)
Isoniazid is a prodrug that is activated by the mycobacterial enzyme KatG.
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Mechanism: It inhibits the synthesis of mycolic acids, which are essential components of the waxy mycobacterial cell wall.
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Result: Without a cell wall, the bacteria lose structural integrity and die.
2. Pyridoxine Hydrochloride (The Neuroprotective Agent)
Isoniazid interferes with the metabolism of Vitamin B6 in the human body.
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The Problem: INH forms a complex with Vitamin B6 and inhibits the enzyme pyridoxine kinase, leading to a deficiency.
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The Result: Without Pyridoxine, patients often develop peripheral neuropathy (tingling, numbness, or “pins and needles” in the hands and feet).
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The Solution: Including Pyridoxine in the tablet prevents this nerve damage, ensuring better patient compliance during long-term TB therapy.
The Manufacturer’s Perspective: Formulation & Export
From a production standpoint in a WHO-GMP facility, this combination is a high-demand “Essential Medicine”:
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Fixed-Dose Combination (FDC) Stability: Isoniazid is sensitive to moisture and can react with certain excipients (reducing sugars like lactose) through the Maillard reaction, which can cause the tablets to discolor. We utilize specialized, non-reactive diluents to ensure stability.
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Dose Ratios: While INH is typically 100 mg or 300 mg, the Pyridoxine dose is usually 10 mg to 50 mg. We utilize validated blending processes to ensure micro-dose uniformity of the Vitamin B6 across the entire batch.
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Packaging for Global Trade: TB is endemic in high-humidity regions. We utilize Alu-Alu or high-barrier PVC/PVDC blister packaging to ensure a 36-month shelf life for export to Zone IVb regions (Africa, SE Asia, and CIS countries).
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B2B & Public Health Tenders: This product is a staple for the Global Drug Facility (GDF) and national TB programs. Our Mumbai facility provides the necessary CTD/eCTD Dossiers to support international supply.