Drinking grapefruit juice may be an inexpensive way to reduce cyclosporine dosages, but the unpredictable nature of the inhibition of CYA metabolism has not vindicated this practice. Ketoconazole and diltiazem, purer entities of CYP3A4 inhibitors,
have been used successfully in this respect. Patients unable to obtain therapeutic CYA levels with orally administered cyclosporine due to inadequate absorption can been placed on either of these agents to achieve this goal.