CYP450 activities before and after Roux-en-Y gastric bypass: correlation with their intestinal and liver content.

ABSTRACT

BACKGROUND: Several anatomic and physiologic changes occur after Roux-en-Y gastric bypass (RYGB) and its associated weight loss. At present, no single unified model can predict changes in drug metabolism associated with either RYGB surgery or weight loss. OBJECTIVE: The aim of this longitudinal human study was to measure the activity of the 5 most important Cytochrome P450 (CYP) involved in drug metabolism in patients with obesity before and after RYGB. Jejunal and liver biopsies obtained during bariatric surgery were used to measure CYP amount, and correlation between jejunal and hepatic content was estimated. SETTING: French university hospital. METHODS: Eleven volunteers with a mean body mass index of 44.1 (39.4-50.0) kg/m2 participated in the study. CYP1 A2, CYP2 C9, CYP2 C19, CYP2 D6, and CYP3 A4/A5 activities were measured with a cocktail approach before surgery (visit 1), 5 to 8 weeks after surgery (visit 2), and 25 to 30 weeks after surgery (visit 3). RESULTS: CYP3 A4/A5 and CYP2 C9 metabolic ratios were transitorily and significantly increased immediately after surgery (visit 2 versus 1). RYGB procedure does not lead to significant change in CYP activity 25 to 30 weeks after surgery (visit 3 versus 1). Samples obtained during surgery showed significant correlation between intestinal and liver contents of CYP2 C9 and CYP3 A4/A5. Except for liver CYP1 A2 content, CYP metabolic activities were not correlated to their intestinal or liver contents. CONCLUSIONS: This study showed that RYGB does not lead to a significant change in CYP activity 25 to 30 weeks after surgery. However, CYP3 A4/A5 and CYP2 C9 activities were transitorily and significantly increased in the immediate postoperative context (<1 mo), representing a situation at risk of reduced drug exposure for several drugs that have a narrow therapeutic window. In addition, considering high interindividual variability in liver contents and activity of CYP3 A4 and CYP2 C9, patients receiving drugs highly metabolized by these 2 CYPs should be closely monitored in the immediate postoperative period.