H2-receptor antagonists reduce the absorption of
itraconazole (AUC reduced by about 50%),
ketoconazole (AUC reduced by 60% and even 95% in some reports) and
posaconazole (AUC reduced by about 40%).
The manufacturers recommend that if
H2-receptor antagonists are used, itracona- zole and
ketoconazole should be given with an acidic drink (such as cola), which increase their bioavailability. Posaconazole may also be given with an acidic drink to improve its bioavailability with
H2-receptor antagonists. However, the manufacturers currently recommend avoiding concurrent use. Fluconazole and
voriconazole do not appear to interact and may therefore be suitable alternatives in some cases.