Drug-Drug Interactions among Kidney Transplant Recipients in The Outpatient Setting.

Background: Number of patients undergoing kidney transplantation is ever increasing. Drug-drug interactions (DDIs) can complicate transplant patient's treatment course.

Objective: To investigate patterns and factors associated with potential DDIs in kidney transplant recipients under maintenance immunosuppressive regimen at a referral transplantation center in Shiraz, Iran.

Methods: 390 eligible kidney transplant outpatients referred to Motahhari clinic and one of the attending nephrologist's private office during an18-month period were assessed for DDIs. Using the Lexi-Interact online drug interactions software, the prescribed drugs were assessed for the number and type of potential DDIs. Only type D and X interactions were considered eligible for inclusion.

Results: During the study period, 344 DDIs were detected of which, 290 were type D; 54 were type XDDIs. 81% of the detected DDIs were pharmacokinetics. Interaction between cyclosporine + mycophenolic acid (32.3%) was the most frequent DDIs followed by cyclosporine + atorvastatin (11.3%). Immunosuppressant (43.44%) was the most frequently used medication responsible for DDIs. Number of co-administered medications (OR: 1.34, 95% CI: 1.12-1.51) and cyclosporine as main immunosuppressive main drug (OR: 10.43, 95% CI: 6.24-17.42) were identified as independent risk factors for DDIs.

Conclusion: Major DDIs were common in kidney transplant recipients. Considering the importance of DDIs in kidney transplant patients, more attention is warranted in this regard by health care members, especially physicians and pharmacists.