Hydrochlorothiazide Fluconazole

Drugs that may affect fluconazole include cimetidine, hydrochlorothiazide, and rifampin. Drugs that may be affected by fluconazole include alfentanil, benzodiazepines, buspirone, carbamazepine, cisapride, oral contraceptives, corticosteroids, cyclosporine, haloperidol, HMG-CoA reductase inhibitors, losartan, nisoldipine, phenytoin, protease inhibitors, rifabutin, sirolimus, sulfonylureas, tacrolimus, theophylline, tolterodine, tricyclic antidepressants, vinca alkaloids, warfarin, zidovudine, and zolpidem. 

Hydrochlorothiazide modestly increases the levels of fluconazole, but this is unlikely to be clinically relevant. 

The manufacturer notes that, in 13 healthy subjects, hydrochlorothiazide 50 mg daily increased the AUC and plasma levels of fluconazole 100 mg daily for 10 days by about 40%. They attribute these changes to a reduction in the renal clearance of fluconazole. However they say it is unlikely that a change in the fluconazole dosage will be needed in patients taking diuretics, but that the interaction should be borne in mind. Any interaction is almost certainly of no relevance in patients taking a single dose of fluconazole for genital candidiasis. 

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