✅ Active Ingredient Overview Table:
| 🔬 Active Ingredient (Generic Name): | Isoniazid (INH) |
|---|---|
| 💊 Indication: | Tuberculosis (TB) Treatment, Latent TB Infection Prophylaxis |
| 🇺🇸 US Brand Equivalent: | Isoniazid (Generic), Nydrazid (Brand) |
| 🏭 Manufacturer: | Macleods Pharmaceuticals Pvt Ltd (Founded: 1988) |
| 📦 Packaging: | 10 Tablets per Strip |
| 🧪 Strength: | 300 mg |
| 🚚 Delivery Time: | 6–15 days |
🌿 What is Isoniazid 300 mg (Solonex)?
Solonex 300 mg tablets contain Isoniazid, a first-line antitubercular agent that works by inhibiting mycolic acid synthesis in Mycobacterium tuberculosis. This bactericidal action disrupts the bacterial cell wall, leading to rapid bacterial death. Solonex is indicated for the intensive and continuation phases of TB treatment and for prophylaxis in individuals with latent TB infection.
Often used in fixed-dose combinations for TB regimens, Isoniazid remains crucial for both active disease management and prevention. Its effectiveness, low cost, and well-established safety profile make it indispensable in global TB control efforts.
🧬 Pharmacology & Mechanism of Action
| Attribute | Detail |
|---|---|
| Chemical Formula | C6H7N3O |
| Molecular Weight | 137.14 g/mol |
| Mechanism | Prodrug activated by mycobacterial catalase-peroxidase (KatG) → forms reactive species that inhibit mycolic acid synthesis → disrupts cell wall integrity → bactericidal against replicating M. tuberculosis |
| Absorption | ~100% oral bioavailability |
| Distribution | Widely distributes in body fluids; penetrates cerebrospinal fluid and macrophages |
| Metabolism | Hepatic acetylation (fast and slow acetylator phenotypes) |
| Half-Life | Fast acetylators: ~1–2 hours; Slow acetylators: ~3–5 hours |
💡 Indications & Usage
| Condition | Dosage & Regimen |
|---|---|
| Active TB (Intensive Phase, Adults) | • 5 mg/kg (max 300 mg) once daily for first 2 months as part of 4‑drug regimen (INH, Rifampicin, Pyrazinamide, Ethambutol) |
| Active TB (Continuation Phase, Adults) | • 5 mg/kg (max 300 mg) once daily for 4 months with Rifampicin |
| Latent TB Infection Prophylaxis (Adults) | • 300 mg once daily for 6–9 months; alternatively, 900 mg twice weekly under DOT |
| Pediatric TB Therapy | • 10–15 mg/kg once daily (max 300 mg) as per weight-based dosing in combination regimens |
Administration Tips:
- Take on an empty stomach (30–60 minutes before meals) to enhance absorption.
- Administer with pyridoxine (Vitamin B6) 10–25 mg daily to prevent peripheral neuropathy.
- Monitor baseline liver function tests, complete blood count, and visual acuity if on Ethambutol.
⚠️ Warnings & Side Effects
Common Adverse Effects:
- Hepatotoxicity (elevated transaminases)
- Peripheral neuropathy (increased risk without pyridoxine supplementation)
- Gastrointestinal upset (nausea, vomiting)
- Rash, fever
Serious (Rare):
- Acute liver failure (monitor LFTs monthly)
- Severe hypersensitivity reactions (DRESS syndrome)
- Optic neuritis (visual disturbances; monitor if on Ethambutol)
Precautions:
- Hepatic Impairment: Use caution in patients with pre-existing liver disease; consider dose adjustment or alternative regimen.
- HIV Co-infection: Monitor for drug interactions with antiretrovirals; adjust regimen accordingly.
- Pregnancy & Breastfeeding: Category C; use when benefits outweigh risks; cross placenta and excreted in breast milk.
- G6PD Deficiency: Risk of hemolysis—monitor hematologic parameters.
- Neuropathy Prevention: Always co-administer pyridoxine to reduce neuropathic risk, especially in malnourished, diabetic, or alcoholic patients.
🏥 Storage Instructions
Store Solonex 300 mg tablets at 20–25°C in original blister packaging. Protect from moisture and light. Keep out of reach of children. Discard any expired tablets.
🌐 Availability & Purchasing
- United States: Prescription-only; Isoniazid generics widely available.
- United Kingdom & EU: Prescription required; part of National TB program regimens.
- Australia: Prescription necessary; supplied through TB specialty clinics.
Importing Solonex from India:
Importing Isoniazid 300 mg from India may reduce costs. Ensure valid prescription, adhere to national importation regulations, and verify quality certification (e.g., WHO‑GMP) to avoid customs delays.
🔗 Internal Links to Authoritative Resources
🔗Related Antitubercular Therapies (Indian Brands)
- Pyrazinamide 500 mg – Pyrazinamide by Intas Pharmaceuticals for intensive phase.
🎥 Educational Video on Isoniazid Therapy
👨⚕️ Expert Insight: Dr. Anjali Mehta, Infectious Disease Specialist
“Isoniazid remains a cornerstone of TB therapy for both active disease and latent infection. Its potency and affordability make it indispensable, but vigilant monitoring for hepatotoxicity and neuropathy is essential for patient safety.”




