Absence of a dose-response of cyclosporine levels to clinically used dosesof diltiazem and verapamil

We examined the effect of different doses of calcium channel blockers on pl asma cyclosporine levels. As previously reported by multiple investigators, we observed that the administration of verapamil or diltiazem, but not nif edipine or isradipine, caused a significant increase in plasma cyclosporine levels achieved for a given dose of cyclosporine. In this article, we show that the effect of verapamil and diltiazem on cyclosporine levels appears to be independent of dosage within their usual prescription range. (C) 1999 by the National Kidney Foundation, Inc.