1. Clinical Overview
Roxithromycin is a semi-synthetic macrolide antibiotic derived from erythromycin. It is a broad-spectrum antibiotic with an extended spectrum and improved pharmacokinetic profile compared to older macrolides. It acts by inhibiting bacterial protein synthesis. It is particularly effective against atypical pathogens and is widely used in India for respiratory, skin, and soft tissue infections due to its convenient twice-daily dosing and good tolerability profile.
| Onset | Duration | Bioavailability |
|---|---|---|
| Clinical improvement is usually observed within 48-72 hours of initiating therapy. | Approximately 12 hours, supporting a twice-daily dosing regimen. | Approximately 50-60% after oral administration. |
2. Mechanism of Action
Roxithromycin reversibly binds to the 50S ribosomal subunit of susceptible bacteria, specifically at the peptidyl transferase center of the 23S rRNA. This binding inhibits the translocation step of protein synthesis, where the growing peptide chain moves from the A-site to the P-site on the ribosome. This results in the premature dissociation of the peptidyl-tRNA complex, halting bacterial protein production.
3. Indications & Uses
- Upper Respiratory Tract Infections (Pharyngitis, Tonsillitis, Sinusitis, Otitis Media)
- Lower Respiratory Tract Infections (Acute Bacterial Bronchitis, Community-Acquired Pneumonia, including atypical pneumonia)
- Skin and Soft Tissue Infections (Folliculitis, Furunculosis, Cellulitis, Erysipelas)
4. Dosage & Administration
Adult Dosage: 150 mg orally twice daily (every 12 hours) OR 300 mg once daily. Standard treatment duration is 5 to 10 days.
Administration: Tablet should be swallowed whole with a glass of water. Can be taken with or without food. If gastrointestinal upset occurs, administer with food. Maintain consistent timing of doses.
5. Side Effects
Common side effects may include:
- Nausea
- Abdominal pain/discomfort
- Diarrhea (non-Clostridioides difficile)
- Headache
- Altered taste sensation
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Warfarin/Acenocoumarol | Increased anticoagulant effect, risk of bleeding. | Major |
| Ergotamine/Dihydroergotamine | Risk of severe peripheral vasospasm and ischemia (contraindicated). | Major |
| Theophylline | Increased theophylline plasma levels, risk of toxicity (nausea, seizures). | Moderate |
| Digoxin | Increased digoxin bioavailability, risk of digitalis toxicity. | Moderate |
| Cyclosporine | Increased cyclosporine levels, risk of nephrotoxicity. | Moderate |
| Midazolam, Triazolam | Enhanced sedative effect. | Moderate |
| Statins (Simvastatin, Atorvastatin) | Increased risk of myopathy/rhabdomyolysis. | Moderate |
| Antacids (Al, Mg) | Slight decrease in roxithromycin absorption. | Minor |
7. Patient Counselling
- DO complete the full prescribed course even if you feel better.
- DO take the tablet at evenly spaced intervals.
- DO inform your doctor about all other medicines you are taking.
- DONT skip doses.
- DONT share your medicine with others.
- DONT take antacids within 2 hours of taking roxithromycin.
8. Toxicology & Storage
Overdose: Symptoms are an extension of side effects: severe nausea, vomiting, diarrhea, abdominal pain. Potential for hearing loss, severe hepatic dysfunction, and QT prolongation at very high doses.
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.