PSHP 2026 Residency Conference

Purpose: Evaluate the impact of low-dose fluconazole (LDF) versus clotrimazole (CTZ) on tacrolimus (TAC) trough levels, dose adjustments needed to maintain serum levels, and prophylaxis (ppx) of oropharyngeal candidiasis (OC).
Methods: This was a single-center, IRB-exempt, retrospective chart review at Jefferson Einstein Philadelphia Hospital including adult kidney transplant recipients (KTRs) transplanted between 4/1/23 - 4/30/25, who received TAC and OC ppx. They were excluded if they had a multiorgan transplant, history of gastric bypass, concomitant CYP inhibitors/inducers, or positive yeast donor cultures. KTRs received rabbit antithymocyte globulin, mycophenolate, and steroids per protocol. KTRs were stratified based on antifungal received. TAC trough levels were monitored throughout with a difference of >1.5 ng/mL determined to be clinically significant. The primary endpoint was the change in the TAC trough level 7 days after discontinuation of OC ppx. Secondary endpoints included the change in the TAC trough level 14 days after discontinuation, incidence of OC at 30 and 60 days, and the impact of sex, race, and early steroid withdrawal on TAC levels.
Results: Of 139 KTRs, 112 were included in the final analysis, with 71 in the CTZ group and 41 in the LDF group. The mean difference in TAC level change between CTZ and LDF was 1.83 ng/mL 7 days after discontinuation of OC ppx [95% CI (0.4, 3.3); p = 0.0123]. The mean TAC level change on day 7 in the CTZ group was -2.52 ng/mL [95% CI (-3.5, -1.6); p<0.001] and -0.69 ng/mL in the LDF group [95% CI (-1.5, -0.2); p = 0.166]. The mean dose of TAC increased from 6.6 mg to 9.4 mg in CTZ KTRs 14 days after discontinuation while LDF KTRs remained stable. There was a larger TAC level decrease seen in the steroid-free KTRs only in the CTZ group. There were no differences between sex and race. No patients developed OC.
Conclusion: Among KTRs that received OC ppx, there was a larger reduction in tacrolimus trough levels following discontinuation of clotrimazole than with low-dose fluconazole. Both antifungals were effective in preventing OC. This data suggests that low-dose fluconazole is preferred to clotrimazole to minimize drug-drug interactions among KTRs started on tacrolimus for immunosuppression with no difference in OC ppx efficacy.