AMLODIPINE INCREASES CYCLOSPORINE LEVELS IN HYPERTENSIVE RENAL-TRANSPLANT PATIENTS - RESULTS OF A PROSPECTIVE-STUDY

Calcium channel blockers (CCB) are considered the agents of choice to treat hypertension in cyclosporine (CsA)-treated renal transplant pati ents, Verapamil, diltiazem, and nicardipine, bur not nifedipine or isr adipine, can significantly increase CsA levels. The effect of a new CC B, amlodipine, has not been established, However, some hospitals are r outinely switching patients to amlodipine from other CCB for reasons o f cost, A case of a man with stable CsA levels who developed significa ntly increased CsA levels after being changed to amlodipine is present ed along with a prospective trial to formally examine this issue, Elev en hypertensive, CsA-treated renal transplant patients were placed on amlodipine for an average of 6.9 wk and later withdrawn. Three measure ments of CsA trough level, blood pressure, serum creatinine concentrat ion, and BUN were obtained at baseline, during treatment with amlodipi ne, and after withdrawal of amlodipine, CsA levels on amlodipine incre ased an average of 40% above baseline (P = 0.003) and decreased to bas eline (P = 0.001) after amlodipine was withdrawn, despite no significa nt change in CsA dose. Additionally, there was no change in serum crea tinine, BUN, or mean arterial pressure values. Amlodipine can increase CsA levels by an average of 40% in hypertensive renal transplant pati ents, despite a stable CsA dose. This important effect must be conside red when initiating or discontinuing amlodipine or when substituting a mlodipine for other CCB.