Azithromycin (Z-Pack) is Safe in Severe Renal Impairment (eGFR 29)
Azithromycin requires no dose adjustment in patients with an eGFR of 29 mL/min and can be used safely at standard doses. 1
FDA-Approved Dosing in Renal Impairment
No dosage adjustment is recommended for patients with renal impairment (GFR ≤80 mL/min), including those with severe renal dysfunction like your patient with eGFR 29 1
The FDA label explicitly states that mean AUC was similar in subjects with GFR 10-80 mL/min compared to those with normal renal function 1
Caution is advised only in patients with GFR <10 mL/min (essentially end-stage renal disease), where AUC increased by 35% 1
Pharmacokinetic Rationale
Azithromycin is primarily eliminated via biliary excretion, not renal excretion—only approximately 6% of an oral dose appears unchanged in urine 1
Research confirms that neither the area under the curve (AUC), distribution volume, nor maximal plasma concentration are significantly affected by renal insufficiency 2
The extensive tissue distribution (apparent volume of distribution 31.1 L/kg) means plasma levels remain low regardless of renal function 1, 3
Safety Profile in Renal Disease
Azithromycin is not nephrotoxic, unlike aminoglycosides which should be avoided in CKD patients 4
Long-term safety studies (mean duration >5 years) showed no renal toxicity in patients using chronic azithromycin 5
The pharmacokinetics are not significantly altered in patients with mild to moderate renal insufficiency 3
Important Caveats
Monitor for QTc prolongation if the patient is on other QTc-prolonging medications, as 10% of chronic azithromycin users showed borderline or prolonged QTc intervals when combined with other such drugs 5
Hepatic function should be monitored if there is concurrent liver disease, as azithromycin is primarily eliminated hepatically 1
Standard dosing applies: 500 mg Day 1, then 250 mg daily Days 2-5 for most respiratory infections, or 500 mg daily for 3 days for COPD exacerbations 1