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Calcium channel blockers (CCB) are preferred antihypertensive drugs in renal transplant patients. Mibefradil is the first drug of new class of CCB, which selectively blocks T-type calcium ion channels in contrast to other CCB which blocks only L-type channels. In this study, the effects on Mibefradil on blood cyclosporine trough levels were investigated.
Six adult hypertensive renal transplant patients (4 male, 2 female) were included in the study. All patients were using Isradipine and were switched to Mibefradil at 50 mg / day. Systolic and diastolic blood pressures, serum BUN, serum creatinine levels and whole blood cyclosporine trough levels were evaluated weekly while the patient was being treated with Mibefradil and after discontinuation of the therapy.
One week after the mibefradil treatment, CsA levels increased sharply and reached to approximately 350 % of pretreatment levels. Two weeks after resumption to isradipine treatment, blood CsA level decreased back to pretreatment level. Mean arterial pressure, BUN and serum creatinine levels did not show significant change throughout the study period.
Our results have shown that there wasn 't any CCB that elevate blood CsA levels as high as Mibefradil. It should be used with great caution for the prevention of renal dysfunction due to cyclosporine toxicity.