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# Azitgro (azithromycin)
## Overview
Azithromycin is a second-generation macrolide antibiotic (azalide). It exerts bacteriostatic effects by binding to the 50S ribosomal subunit, inhibiting bacterial protein synthesis. It possesses a long terminal half-life (68+ hours), allowing for once-daily dosing and shorter treatment courses.
## Primary Indications
* Community-acquired pneumonia (CAP).
* Acute bacterial exacerbations of COPD.
* Pharyngitis/tonsillitis (due to *S. pyogenes*).
* Skin and skin structure infections.
* Urethritis/cervicitis (*Chlamydia trachomatis*).
* Mycobacterium avium complex (MAC) prophylaxis/treatment.
## Adult Dosing
* **Most infections:** 500 mg orally on Day 1, followed by 250 mg once daily on Days 2–5.
* **Common "Z-Pak" regimen:** 500 mg Day 1, then 250 mg daily for 4 days.
* **Chlamydial urethritis/cervicitis:** 1 gram orally as a single dose.
* **CAP/Respiratory infections (alternative):** 500 mg once daily for 3 days.
## Pediatric Dosing
* **General infections:** 10 mg/kg once daily on Day 1 (max 500 mg), followed by 5 mg/kg once daily on Days 2–5 (max 250 mg).
* **Acute otitis media (alternative):** 30 mg/kg as a single dose OR 10 mg/kg once daily for 3 days.
* **CAP:** 10 mg/kg on Day 1, followed by 5 mg/kg once daily for 4 days.
## Dose Adjustments
* **Renal Impairment:** No dosage adjustment indicated for mild to moderate impairment (CrCl >10 mL/min). Use caution in severe renal impairment.
* **Hepatic Impairment:** Use with caution; azithromycin is primarily eliminated via biliary excretion.
## Contraindications
* Known hypersensitivity to azithromycin, erythromycin, or any macrolide.
* History of cholestatic jaundice/hepatic dysfunction associated with prior use.
## Adverse Effects
* **Common:** Diarrhea, nausea, abdominal pain, vomiting.
* **Serious:** QTc prolongation (torsades de pointes risk), hepatotoxicity, *C. difficile*-associated diarrhea, and life-threatening hypersensitivity reactions (DRESS, SJS/TEN).
## Key Drug Interactions
* **QT Prolonging Agents:** Additive risks with fluoroquinolones, ondansetron, or antiarrhythmics (Class IA/III).
* **Warfarin:** May potentiate the anticoagulant effect; monitor INR.
* **Digoxin:** May increase digoxin serum concentrations.
* **Statins:** Increased risk of myopathy (e.g., simvastatin, atorvastatin).
## Monitoring
* **Cardiac:** Monitor ECG in patients with pre-existing proarrhythmic conditions or electrolyte imbalances (hypokalemia/hypomagnesemia).
* **Hepatic:** Monitor for signs of jaundice or elevated LFTs if therapy is prolonged.
* **GI:** Monitor for persistent diarrhea (rule out *C. diff*).
## Clinical Pearls
* Azithromycin is not effective against methicillin-resistant *Staphylococcus aureus* (MRSA) or common Gram-negative enteric pathogens, limiting its use for empiric treatment in severe sepsis.
* Bioavailability is reduced by food; oral suspension and tablets can generally be taken with or without food, though some clinicians prefer fasting for consistency.
* High tissue penetration makes it effective for intracellular pathogens like *Chlamydia* and *Mycoplasma*.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice protocols vary by institution and regional resistance patterns. Always verify current prescribing information, contraindications, and patient-specific drug interactions via official resources (e.g., package inserts, Lexicomp, or UpToDate) before prescribing or administering medication.
