Generic
Azithromycin
308 brands available in the market
At a glance
Azithromycin is a macrolide antibiotic used to treat bacterial infections of the respiratory tract, ear, nose, throat, lungs, skin, and eyes. It is also effective in typhoid fever and some sexually transmitted diseases like gonorrhea.
Description
Azithromycin is a semisynthetic azalide antibiotic that binds to the 50S ribosomal subunit of bacteria to inhibit protein synthesis. It is acid-stable, well absorbed on an empty stomach, and actively transported to infection sites due to high concentration in phagocytes. Tissue concentrations can be 50 times higher than plasma. Its long half-life (68 hours) allows for short-course therapy.
Indications
Respiratory tract infections (bronchitis, pneumonia, sinusitis), otitis media, pharyngitis/tonsillitis, skin and soft tissue infections, sexually transmitted infections (chlamydia, gonorrhea), typhoid fever, Mycobacterium avium complex (MAC) prophylaxis.
Therapeutic class
Macrolide Antibiotic
Pharmacological class
Azalide Antibiotic
Pharmacology
Azithromycin is acid-stable and can be taken orally without protection from gastric acids. It is readily absorbed, with greater absorption on an empty stomach. Peak concentration in adults is 2.1-3.2 hours. Due to high concentration in phagocytes, it is actively transported to infection sites. During active phagocytosis, large concentrations are released. Tissue concentrations can be over 50 times higher than plasma (ion trapping and high lipid solubility). Half-life (68 hours) allows maintenance of bacteriostatic levels for several days. Biliary excretion of unchanged drug is the major route of elimination.
Mechanism of action
Azithromycin binds to the 50S ribosomal subunit of bacteria, inhibiting protein synthesis, which stops bacterial growth and prevents the spread of infection. Nucleic acid synthesis is not affected.
Dosage
Adult Dose:
- Respiratory, skin & soft tissue infections: 500 mg once daily for 3 days OR 500 mg on Day 1, then 250 mg on Days 2-5
- Chlamydia: 1 g single dose OR 500 mg on Day 1, then 250 mg on Days 2-3
- Gonorrhea: 2 g single dose
- Typhoid fever: 500 mg once daily for 7-10 days
- Sinusitis: 500 mg once daily for 3 days
- Community-acquired pneumonia (IV): 500 mg IV once daily for 2 days, then oral 500 mg once daily (total 7-10 days)
- Pelvic inflammatory disease (IV): 500 mg IV once daily for 1-2 days, then oral 250 mg once daily (total 7 days)
Pediatric Dose (weight-based, >6 months):
- Otitis media, pneumonia, sinusitis: 10 mg/kg once daily for 3 days
- Pharyngitis/tonsillitis (≥2 years): 12 mg/kg once daily for 5 days
- Weight-based specific doses (3 days): 15-25 kg: 200 mg; 26-35 kg: 300 mg; 36-45 kg: 400 mg
- Typhoid fever: 500 mg once daily for 7-10 days
Administration
Oral: Take at least 1 hour before or 2 hours after meals on an empty stomach. Separate from aluminum/magnesium antacids by 2 hours. Swallow tablet whole; do not chew or crush.
Suspension reconstitution: Shake bottle well to loosen powder. Add boiled and cooled water to the water mark. Shake until powder is completely mixed.
IV Infusion: For IV infusion only. Infuse over 1 hour.
Missed dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not double the dose.
Side effects
Common side effects: Nausea, vomiting, abdominal pain/cramps, diarrhea, flatulence, loose stools.
Allergic reactions: Rash, photosensitivity, serious hypersensitivity (angioneurotic edema, anaphylaxis).
Hepatic: Reversible elevations in liver transaminases, rare cholestatic jaundice.
Other: Transient mild reductions in neutrophil counts, reversible hearing impairment (with high-dose prolonged use).
Serious side effects (rare – consult doctor): Allergic reactions (rash, swelling of face/throat, difficulty breathing), QT prolongation (irregular heartbeat), Clostridium difficile-associated diarrhea.
Precautions & warnings
Consult your doctor during pregnancy and lactation. Contraindicated in liver disease. Caution in severe renal impairment (no data for CrCl <40 mL/min). Inform your doctor of any history of allergy. Complete the full course even if you feel better. Separate from antacids by 2 hours. Allergic reactions with azithromycin may recur and require prolonged observation.
Contraindications
Hypersensitivity to azithromycin, erythromycin, any macrolide or ketolide antibiotic. Hepatic disease. Coadministration with ergot derivatives. Coadministration with pimozide.
Drug interactions
Antacids (aluminum/magnesium): Decrease azithromycin absorption – separate by 2 hours.
Digoxin: May increase digoxin levels (some macrolides impair gut metabolism) – monitor digoxin levels.
Cyclosporine: Caution required; monitor cyclosporine levels and adjust dose accordingly.
Warfarin: Continue monitoring prothrombin time (although azithromycin does not alter anticoagulant effect).
Theophylline: Monitor theophylline levels.
Ergot derivatives: Coadministration contraindicated (theoretical risk of ergotism).
Carbamazepine: No significant effect.
Terfenadine: No significant effect on pharmacokinetics or QTc interval.
Methylprednisolone: No significant effect.
Food interactions
Alcohol: Caution advised when consuming alcohol as it may increase liver problems and side effects.
Antacids: Take azithromycin at least 1 hour before or 2 hours after antacids.
Use in pregnancy
Pregnancy Category: B. Animal reproduction studies have shown no evidence of fetal harm. No adequate and well-controlled studies in pregnant women. Use only if adequate alternatives are not available.
Pregnancy Category: B — always consult a doctor before taking during pregnancy.
Use in lactation
It is not known whether azithromycin is secreted in breast milk. Use with caution.
Pediatric use
Under 6 months: Safety and efficacy not established.
6 months-12 years: Weight-based dosing applies.
≥12 years: Adult dose applies.
Injection: Safety and efficacy not established in children/adolescents under 16 years.
Geriatric use
No dosage adjustment needed for elderly patients.
Renal / hepatic impairment
Renal impairment: No dose adjustment needed in mild renal impairment (CrCl >40 mL/min); no data for severe renal impairment – caution required.
Hepatic impairment: Contraindicated in hepatic disease (liver is the principal route of excretion).
Overdose effects
No specific data on overdosage. Typical symptoms of macrolide overdose: hearing loss, severe nausea, vomiting, diarrhea. Gastric lavage and general supportive measures are indicated.
Storage conditions
Store in a dry place away from light and heat. Keep out of reach of children.
Chemical structure
C₃₈H₇₂N₂O₁₂