Influence of bariatric surgery on erythromycin absorption

Area of Science:

• Pharmacology
• Gastroenterology
• Surgery

Background:

• Morbid obesity presents challenges in drug absorption and distribution.
• Bariatric surgery alters gastrointestinal anatomy and physiology, potentially impacting drug bioavailability.

Purpose of the Study:

• To evaluate the pharmacokinetic changes of erythromycin in morbidly obese patients undergoing bariatric surgery.
• To assess the impact of bariatric surgery on erythromycin absorption and serum levels.

Main Methods:

• Seven morbidly obese patients received a single 250-mg oral dose of erythromycin Filmtab postoperatively and preoperatively.
• Serial blood samples were collected over 12 hours to determine erythromycin serum concentrations.
• Pharmacokinetic parameters including peak concentration (Cmax), time to peak concentration (Tmax), and area under the curve (AUC) were analyzed.

Main Results:

• Post-surgery, mean Cmax decreased from 1.04 to 0.55 µg/ml, and mean Tmax increased from 3.9 to 6.7 hours.
• Mean weight-corrected AUC showed a 41% reduction after surgery.
• Two patients exhibited no detectable erythromycin serum levels postoperatively.

Conclusions:

• Bariatric surgery significantly alters erythromycin pharmacokinetics, leading to reduced absorption and lower serum concentrations.
• The evaluated erythromycin product demonstrates questionable clinical utility in post-bariatric surgery patients.
• Further studies are warranted to optimize antibiotic dosing in this population.