1. Clinical Overview
A fixed-dose combination (FDC) of a second-generation fluoroquinolone antibiotic (Norfloxacin) and a nitroimidazole antimicrobial (Tinidazole). This combination provides broad-spectrum coverage against both aerobic and anaerobic bacteria, as well as protozoa, making it highly effective in treating mixed gastrointestinal and genitourinary infections common in the Indian context. It is widely prescribed for infectious diarrhea, giardiasis, and amebiasis.
| Onset | Duration | Bioavailability |
|---|---|---|
| Norfloxacin: 1-2 hours. Tinidazole: 1-2 hours. | Norfloxacin: Approximately 12 hours (twice-daily dosing). Tinidazole: Approximately 24 hours (once-daily dosing). | Norfloxacin: 30-40%. Tinidazole: >90%. |
2. Mechanism of Action
Norfloxacin inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, enzymes essential for DNA replication, transcription, and repair, leading to rapid bactericidal activity. Tinidazole enters microbial cells, undergoes nitro-reduction to form cytotoxic intermediates that damage DNA and inhibit nucleic acid synthesis, leading to cell death in anaerobic bacteria and protozoa.
3. Indications & Uses
- Acute infectious diarrhea (bacterial & protozoal mixed etiology)
- Giardiasis (Lambliasis)
- Intestinal amebiasis (Amebic dysentery)
- Traveler's diarrhea (in specific high-risk scenarios)
4. Dosage & Administration
Adult Dosage: One tablet (Norfloxacin 400mg + Tinidazole 600mg) twice daily for 5-7 days. For giardiasis/amebiasis: Often prescribed as once or twice daily for 3-5 days, as per severity.
Administration: Take tablet with a full glass of water, preferably 1 hour before or 2 hours after meals for optimal absorption. Do not crush or chew. Maintain adequate hydration. Avoid concomitant administration with antacids, sucralfate, or iron/zinc supplements (separate by 2-4 hours).
5. Side Effects
Common side effects may include:
- Nausea
- Metallic/bitter taste in mouth (Tinidazole)
- Headache
- Dizziness
- Abdominal discomfort
- Diarrhea (including C. difficile associated diarrhea)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Antacids (Al, Mg, Ca), Sucralfate, Iron/Zinc Salts | Markedly reduce absorption of Norfloxacin due to chelation | Major |
| Warfarin | Tinidazole may inhibit metabolism, increasing INR and bleeding risk | Major |
| Theophylline | Norfloxacin may inhibit metabolism, increasing theophylline levels and toxicity | Major |
| Cyclosporine | Norfloxacin may increase cyclosporine levels, risk of nephrotoxicity | Moderate |
| NSAIDs (e.g., Ibuprofen) | May increase risk of CNS stimulation and seizures with Norfloxacin | Moderate |
| Oral Hypoglycemics (e.g., Glyburide) | Tinidazole may potentiate effect, risk of hypoglycemia | Moderate |
| Phenobarbital, Phenytoin | May increase metabolism of Tinidazole, reducing its efficacy | Moderate |
| Alcohol | Disulfiram-like reaction with Tinidazole (flushing, nausea, vomiting, tachycardia) | Major |
7. Patient Counselling
- DO complete the full course even if you feel better.
- DO take the tablet with plenty of water, on an empty stomach if possible.
- DO separate this medicine from antacids, dairy, or multivitamins by 2-4 hours.
- DO report any tendon pain, swelling, or difficulty walking immediately.
- DO NOT consume ANY alcohol during treatment and for 3 days after the last dose.
- DO NOT share this medicine with others who have similar symptoms.
8. Toxicology & Storage
Overdose: Nausea, vomiting, dizziness, ataxia, seizures, CNS depression. Crystalluria with Norfloxacin in alkaline urine.
Storage: Store below 30°C in a cool, dry place, protected from light and moisture. Keep out of reach of children. Do not use after the expiry date printed on the pack.