Objective: To report a case of an obese patient who had undergone renal transplantation and who had subtherapeutic levels of serum cyclosporine after treatment with orlistat.
Methods: The clinical and laboratory findings are presented, and the few cases reported in the literature are reviewed.
Results: A 29-year-old woman had subtherapeutic plasma levels of cyclosporine after orlistat treatment (360 mg/day) was initiated. The subtherapeutic levels persisted even though orlistat was administered the recommended 2 hours before ingestion of cyclosporine and even though the dosage of orlistat was decreased to only 240 mg/day. Because an increase of body weight is common after organ transplantation, treatment with orlistat has been used. In such patients, however, six cases of reduced therapeutic plasma levels of cyclosporine have been reported. Although a drug-drug interaction has been suggested, this case suggests that the decreased plasma cyclosporine levels are due to reduced absorption of fats rather than a drug-drug interaction. Because this patient was unable to adhere to a low-fat diet, she experienced severe diarrhea, a factor that may have dramatically diminished the absorption of cyclosporine.
Conclusion: Adherence to a low-fat diet should be strongly recommended if orlistat is prescribed to patients taking cyclosporine. Moreover, strict surveillance of the plasma concentration of cyclosporine is important.