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Published on: November 8, 2015
Impact of Clotrimazole Fungal Prophylaxis on Tacrolimus Exposure in Kidney Transplant Recipients: A Retrospective
Anas El-Sayed1, Jennifer Vidal1, Kamran Khanmoradi2
1Department of Pharmacy, Einstein Medical Center Philadelphia, Philadelphia, Pennsylvania.
Abstract:
Tacrolimus, an immunosuppressant prescribed to reduce the risk of organ rejection, is metabolized by cytochrome P450 and is a substrate for P-glycoprotein. Many medications affect tacrolimus concentrations, making it difficult to maintain exposure within its narrow therapeutic index. Clotrimazole troches, prescribed to posttransplant recipients immediately for the first 30 days for oral candidiasis prevention, are considered nonsystemic. However, data suggest a potential drug interaction, affecting tacrolimus exposure. To assess the magnitude of the effect of clotrimazole on tacrolimus trough levels, 97 kidney transplant recipients, on a stable dose of tacrolimus, were retrospectively evaluated. Tacrolimus trough concentrations were analyzed 7 and 14 days before and after discontinuation of clotrimazole. The median change in tacrolimus trough level was -1.3 ng/mL (confidence interval, -2.5, -1.0; P < .001) at day 7 and -2.8 ng/mL (confidence interval, -3.3, -1.6; P < .001) at day 14 after clotrimazole discontinuation, from a median baseline of 8.9 ng/mL. Overall, a reduction in tacrolimus level was observed in 60% of patients after discontinuation of clotrimazole. When assessing the effect of race and sex, no influence was found on the degree of change in tacrolimus level after clotrimazole discontinuation. In conclusion, clotrimazole exerts a significant interaction on tacrolimus where close monitoring of tacrolimus trough levels after discontinuation of clotrimazole is warranted.
Insights
Clotrimazole troches significantly reduce tacrolimus levels in kidney transplant patients. Close monitoring of tacrolimus trough concentrations is essential after discontinuing clotrimazole to prevent subtherapeutic exposure.
Area of Science:
- Pharmacology
- Transplantation Medicine
- Drug Interactions
Background:
- Tacrolimus is a critical immunosuppressant for organ transplant recipients.
- Its narrow therapeutic index necessitates careful management of drug concentrations.
- Clotrimazole, used for oral candidiasis prevention, is often presumed nonsystemic.
Purpose of the Study:
- To evaluate the impact of clotrimazole troches on tacrolimus trough levels in kidney transplant recipients.
- To quantify the change in tacrolimus exposure following clotrimazole discontinuation.
Main Methods:
- Retrospective analysis of 97 kidney transplant recipients on stable tacrolimus doses.
- Tacrolimus trough levels were measured 7 and 14 days before and after clotrimazole discontinuation.
Main Results:
- Discontinuation of clotrimazole led to a median decrease in tacrolimus trough levels of -1.3 ng/mL at 7 days and -2.8 ng/mL at 14 days.
- 60% of patients experienced a reduction in tacrolimus levels post-clotrimazole.
- Race and sex did not influence the magnitude of this interaction.
Conclusions:
- Clotrimazole exerts a significant drug interaction with tacrolimus.
- Close monitoring of tacrolimus trough levels is crucial after stopping clotrimazole to ensure therapeutic efficacy.
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