Oral Fluconazole Absorption in a Complicated Post-Roux-en-Y Gastric Bypass Patient: A Case Report

Introduction: Roux-en-Y gastric bypass (RYGB) is a surgical weight-loss procedure that combines gastric restriction with malabsorption for weight reduction. There is currently a paucity of data to guide pharmacists and healthcare providers in optimizing oral medication therapy in patients with a history of bariatric surgery. Fluconazole is a commonly used triazole antifungal with high oral bioavailability. The literature is limited regarding how RYGB affects oral fluconazole absorption. Case: We investigated fluconazole oral bioavailability in a patient with a history of RYGB status-post revision with esophagojejunal anastomosis. The patient had been maintained on combination therapy with intravenous (IV) micafungin and oral fluconazole due to persistent candidemia prior to source control and concerns regarding fluconazole absorption. On admission, the patient was switched to IV fluconazole in the setting of possible small bowel obstruction. Steady-state fluconazole trough levels obtained during IV and oral therapy were 41.9 μg/mL and 44.4 μg/mL, respectively. Conclusion: We were able to demonstrate oral fluconazole maintains high bioavailability in a patient with RYGB. Fluconazole displays linear pharmacokinetics, therefore the degree of oral absorption reduction would directly correspond to a decreased trough level. Pharmacists and providers should continue to be vigilant when evaluating drug efficacy in patients who have undergone gastric bypass procedures, especially those with malabsorptive mechanisms.