AZASITE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AZASITE (AZASITE).
Azasite (azithromycin ophthalmic solution) is a macrolide antibiotic that binds to the 50S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis.
| Metabolism | Not significantly metabolized; primarily excreted unchanged in bile and urine. |
| Excretion | Primarily hepatic/biliary (fecal) as unchanged drug: ~70% fecal, ~20% renal (mostly unchanged), ~0.5% urinary as metabolites. |
| Half-life | Terminal elimination half-life: 68-72 hours; facilitates once-weekly dosing for trachoma. |
| Protein binding | ~50-60% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | Vd: ~100 L/kg (extensive tissue penetration; not meaningful for topical use; systemic Vd based on IV data). |
| Bioavailability | Ophthalmic: negligible systemic absorption (<10% of topical dose) due to low corneal permeability and dilution by tears. |
| Onset of Action | Topical ophthalmic: clinical improvement in conjunctivitis within 2-3 days of starting therapy. |
| Duration of Action | Sustained tear film concentrations above MIC90 for Chlamydia trachomatis for at least 7 days after a single dose; full therapeutic effect over 2-3 weeks. |
1 drop of 1% ophthalmic solution to each affected eye twice daily (approximately 12 hours apart) for 2 days, then once daily for 5 days.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No dosage adjustment required for ophthalmic use. |
| Liver impairment | No dosage adjustment required for ophthalmic use. |
| Pediatric use | Safety and efficacy in pediatric patients have not been established; limited data available. |
| Geriatric use | No specific dosage adjustment recommended; use same dosing as for adults. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for AZASITE (AZASITE).
| Breastfeeding | Azithromycin is excreted into human milk after systemic administration; the M/P ratio is approximately 0.90. After ophthalmic administration, systemic absorption is minimal, resulting in negligible exposure to the infant. Considered compatible with breastfeeding; use with caution if eye drops are applied multiple times daily. |
| Teratogenic Risk | Azasite (azithromycin ophthalmic) is classified as FDA Pregnancy Category B. Systemic absorption is minimal after ophthalmic administration. No teratogenic effects have been observed in animal studies at doses up to 200 mg/kg/day (systemic). Limited human data; risk is considered low. First trimester: unlikely to cause major malformations. Second and third trimesters: no specific risks identified. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to azithromycin, erythromycin, or any macrolide antibiotic","Hypersensitivity to any component of the formulation"]
| Precautions | ["Prolonged use may result in overgrowth of nonsusceptible organisms","Contact lens should not be worn during treatment","Do not inject subconjunctivally or introduce into the anterior chamber"] |
| Food/Dietary | No clinically significant food interactions. Administer with or without food as per dosing instructions. |
| Clinical Pearls |
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| Fetal Monitoring | No specific monitoring required beyond routine prenatal care. Monitor for ocular adverse effects (e.g., irritation, hypersensitivity) in the mother. |
| Fertility Effects | No known effects on fertility. Animal studies with systemic azithromycin showed no impairment of fertility. |
| Azasite (azithromycin ophthalmic solution) is a macrolide antibiotic used for bacterial conjunctivitis. Shake well before each use. Avoid contact with contact lenses during treatment. Do not use for more than 14 days. Monitor for signs of hypersensitivity. |
| Patient Advice | Shake the bottle well before each use. · Wash hands before and after application. · Do not touch the dropper tip to any surface. · Remove contact lenses before use; do not reinsert during treatment. · Instill the prescribed number of drops in the affected eye(s). · Avoid wearing eye makeup during treatment. · Finish the entire course of medication even if symptoms improve. · Report any worsening, itching, or swelling to your doctor. |