From the Guidelines
No dosage adjustment of azithromycin is required for patients with impaired renal function, including those with a creatinine level of 2.7 and GFR of 23, as the drug is primarily eliminated through biliary excretion and hepatic metabolism rather than renal clearance. The standard dosing for community-acquired pneumonia should be maintained: 500 mg intravenously on day 1, followed by 250 mg once daily for days 2-5, or alternatively, 500 mg orally on day 1, followed by 250 mg once daily for days 2-5. This recommendation is based on azithromycin's pharmacokinetic properties, as only about 6-12% of the drug is excreted unchanged in the urine, making dose adjustments unnecessary even in severe renal impairment 1. However, it's essential to monitor the patient for potential side effects, including QT prolongation, especially if they are taking other medications that may affect cardiac conduction.
- Key considerations in treating patients with impaired renal function include:
- Monitoring for potential side effects
- Checking for drug interactions with any medications the patient may be taking for their kidney disease or other conditions, as azithromycin is metabolized by the cytochrome P450 system
- Maintaining the standard dosing regimen for community-acquired pneumonia, as dose adjustments are not necessary due to the drug's pharmacokinetic properties.
- In clinical practice, the primary concern is minimizing morbidity, mortality, and improving quality of life, and in this case, the standard dosing of azithromycin is the most appropriate approach, even in patients with severe renal impairment, as supported by the pharmacokinetic properties of the drug 1.
From the FDA Drug Label
Renal Insufficiency No dosage adjustment is recommended for subjects with renal impairment (GFR ≤80 mL/min) The mean AUC0-120 was similar in subjects with GFR 10 to 80 mL/min compared to subjects with normal renal function, whereas it increased 35% in subjects with GFR <10 mL/min compared to subjects with normal renal function. Caution should be exercised when azithromycin is administered to subjects with severe renal impairment.
The recommended azithromycin dosing for Community-Acquired Pneumonia (CAP) in a patient with impaired renal function, specifically a creatinine level of 2.7 and a Glomerular Filtration Rate (GFR) of 23, is 500 mg as a single dose on Day 1, followed by 250 mg once daily on Days 2 through 5. However, caution should be exercised when azithromycin is administered to subjects with severe renal impairment, as the mean AUC0-120 increased 35% in subjects with GFR <10 mL/min compared to subjects with normal renal function 2.
From the Research
Azithromycin Dosing for CAP with Impaired Renal Function
The recommended azithromycin dosing for Community-Acquired Pneumonia (CAP) in patients with impaired renal function is based on several studies.
- A study from 1995 3 found that the pharmacokinetics of azithromycin are not significantly affected by renal insufficiency, suggesting that the dosage regimen in patients with impaired renal function may be the same as in those with normal renal function.
- Key points to consider:
- The area under the plasma concentration curve, distribution volume, and maximal plasma concentration are not significantly affected by renal insufficiency.
- Nonrenal clearance is not affected by renal insufficiency, but the concentration of the substance in the tubular lumen may be increased.
- Other studies have focused on the relationship between serum creatinine, renal function, and the need for adjusted dosing in patients with impaired renal function:
- A 2003 study 4 discussed the definition of worsening renal function in patients with heart failure, highlighting the importance of considering creatinine elevations in the context of renal function.
- Another study from 2003 5 found that serum creatinine is an inadequate screening test for renal failure in elderly patients, emphasizing the need for more accurate measures of renal function.
- A 2009 review 6 discussed pharmacokinetic issues for antibiotics in critically ill patients, including the impact of altered renal function on drug clearance and the need for individualized dosing regimens.
- An earlier study from 1988 7 highlighted the limitations of serum creatinine as a measure of renal function, emphasizing the need for more accurate and sensitive measures of glomerular filtration rate (GFR).
- In the context of azithromycin dosing for CAP in a patient with a creatinine level of 2.7 and a GFR of 23, the study from 1995 3 suggests that the dosage regimen may not need to be adjusted based on renal function alone. However, it is essential to consider the patient's overall clinical condition and other factors that may influence azithromycin pharmacokinetics and efficacy.