Azithromycin

Rhodococcus equi pneumonia in foals (with rifampin); respiratory tract and skin infections in small animals; macrolide antimicrobial. Azalide macrolide antibiotic. Mechanism: binds 50S ribosomal subunit → inhibits bacterial translocation and protein synthesis (bacteriostatic; bactericidal at high tissue concentrations). Exceptional intracellular tissue penetration (10–100× plasma levels); effective against intracellular pathogens (Rhodococcus equi). Long half-life allows once-daily dosing. High oral bioavailability. Key information Administer on empty stomach in foals. Drug interaction: increases cyclosporine and digoxin levels. QT prolongation risk — avoid concurrent use with other QT-prolonging drugs. Foals: used for Rhodococcus equi (combo with rifampin). Store at room temperature.

Oral (suspension or tablets): Administer orally. May be given with food to improve compliance and reduce GI upset. May be given with or without food (food does not significantly affect absorption). Oral suspension: Shake well before each use. Store refrigerated (2–8°C); do not freeze. Foals: oral suspension formulated for pediatric use; weigh dose accurately. IV (human formulation, extra-label): dilute to 2 mg/mL in 0.9% NaCl or D5W; infuse over 60 min. If a dose is missed Administer as soon as you remember. If it is almost time for the next scheduled dose, skip the missed dose and resume the normal schedule. Never double up doses to make up for a missed one. Complete the full antibiotic course.

GI: diarrhea, vomiting, abdominal discomfort. Foals: hyperthermia, tachypnea (especially when combined with rifampin — monitor temperature). QT prolongation (rare). Hepatotoxicity (rare). Superinfection with resistant organisms.

For animals Foals: hyperthermia risk — monitor body temperature daily, especially when combined with rifampin. Mares nursing treated foals: can develop severe diarrhea — separate mares from treated foals, manage hygiene. QT prolongation risk — avoid in patients with QT-prolonging drugs or electrolyte abnormalities. Drug interactions: CYP3A4 — check concurrent medications. For people handling this medication Wash hands thoroughly with soap and water after handling. Avoid contact with eyes; if contact occurs, flush with water for 15 minutes and seek medical attention. Keep out of reach of children. If accidental ingestion occurs, contact Poison Control (1-800-222-1222). Macrolide antibiotic — Wash hands thoroughly with soap and water after handling. after administering. Inform your doctor if taking medications that may interact (QT-prolonging drugs).

Contact your veterinarian. Overdose causes GI signs (vomiting, diarrhea) and cardiac arrhythmias at high doses. Contact your veterinarian, a veterinary emergency clinic, or the ASPCA Animal Poison Control Center (888-426-4435) immediately. Do not induce vomiting unless specifically directed by a veterinary professional.