1. Clinical Overview
Tigecycline is a broad-spectrum glycylcycline antibiotic, structurally derived from minocycline. It is a bacteriostatic agent with activity against a wide range of Gram-positive, Gram-negative, anaerobic, and atypical bacteria, including many multidrug-resistant (MDR) pathogens. It is a critical reserve antibiotic in the Indian context, used primarily for complicated intra-abdominal infections (cIAI) and complicated skin and skin structure infections (cSSSI) when other alternatives are unsuitable due to resistance or allergy.
| Onset | Duration | Bioavailability |
|---|---|---|
| Peak plasma concentrations are achieved within 0.5 to 4 hours post-infusion. | The dosing interval is every 12 hours, supported by a long post-antibiotic effect (PAE). | Not applicable (Intravenous administration only). |
2. Mechanism of Action
Tigecycline inhibits protein synthesis in bacteria by binding reversibly to the 30S ribosomal subunit. This blocks the entry of amino-acyl tRNA molecules into the A site of the ribosome, preventing the incorporation of amino acid residues into elongating peptide chains.
3. Indications & Uses
- Complicated Intra-abdominal Infections (cIAI) caused by susceptible organisms like E. coli, B. fragilis, Enterococcus faecalis.
- Complicated Skin and Skin Structure Infections (cSSSI) caused by susceptible organisms like S. aureus (MRSA & MSSA), Streptococcus pyogenes, E. coli, B. fragilis.
4. Dosage & Administration
Adult Dosage: Initial dose: 100 mg IV single dose, followed by 50 mg IV every 12 hours. Duration: 5 to 14 days based on infection severity and clinical response.
Administration: Reconstitute 50 mg vial with 5.3 mL of 0.9% Sodium Chloride or 5% Dextrose to get 10 mg/mL. Further dilute in 100 mL of compatible IV fluid (NS or D5W). Infuse over 30 to 60 minutes. Flush line before/after with same diluent. Incompatible with amphotericin B, chlorpromazine, methylprednisolone, voriconazole.
5. Side Effects
Common side effects may include:
- Nausea (26-35%)
- Vomiting (16-20%)
- Diarrhea (12-14%)
- Injection site reactions
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Warfarin | Tigecycline may prolong PT/INR; increased monitoring required. | Moderate |
| Oral Contraceptives | Potential reduction in contraceptive efficacy; advise alternative non-hormonal methods. | Moderate |
| Proton Pump Inhibitors (e.g., Omeprazole) | Concurrent use may reduce tigecycline absorption if given orally (not relevant for IV). | Minor |
| Live Bacterial Vaccines (e.g., Typhoid, BCG) | Antibiotics may diminish therapeutic effect of live vaccines. | Moderate |
7. Patient Counselling
- Complete the full prescribed course even if you feel better.
- Report severe diarrhea, even if it occurs weeks after finishing the antibiotic.
- Inform all doctors about this medication if you need surgery or dental work.
- Use effective non-hormonal contraception during treatment if applicable.
8. Toxicology & Storage
Overdose: Expected to be an extension of side effects: severe nausea, vomiting, pancreatitis. No specific antidote.
Storage: Store unopened vials at or below 25°C. Protect from light. Reconstituted solution in vial is stable for up to 6 hours at room temperature or up to 48 hours refrigerated (2-8°C). The fully diluted solution in IV bag is stable for up to 24 hours at room temperature or up to 48 hours refrigerated. Do not freeze.