Background: Although azole antifungal agents have been shown to affect the pharmacokinetics of calcineurin inhibitors such as tacrolimus (TAC) and cyclosporine (CyA) by inhibiting drug metabolism, there are few clinical reports on drug interactions between miconazole (MCZ) oral gel and calcineurin inhibitors. In this study, the effects of MCZ oral gel on the blood concentrations of TAC and CyA were investigated.
Methods: In this retrospective study, 18 patients concomitantly administered MCZ oral gel and TAC (9 for dermatomyositis, 3 for myasthenia gravis, 2 for systemic lupus erythematosus, 2 for rheumatoid arthritis, 1 for polymyositis, 1 for prevention of graft-versus-host disease after bone marrow transplantation), and 15 patients concomitantly administered MCZ oral gel and CyA (11 for interstitial pneumonia, 2 for pemphigus, 1 for eosinophilic granulomatosis with polyangiitis, 1 for systemic lupus erythematosus) were evaluated. The dose-adjusted blood concentrations of TAC or CyA were compared before and after the initiation of MCZ oral gel.
Results: The trough blood concentration/dose (C/D) ratios of TAC and CyA increased significantly with the administration of MCZ oral gel. The median C/D ratios of TAC and CyA increased by 108% (range: -44% to 216%) and 44% (range: -34% to 195%), respectively.
Conclusions: These results suggest that MCZ oral gel affects the pharmacokinetics of TAC and CyA. Detailed monitoring of the blood concentrations of these drugs, followed by dose adjustments, is needed for each patient because of the difficulties associated with accurately predicting the degree of the effects of MCZ oral gel.