Antihypertensive effects of long-acting calcium channel blockers on hemodialysis days--a randomized crossover trial between benidipine and nifedipine CR.

BACKGROUND/AIMS: Since antihypertensive effects of most calcium channel blockers largely depend on their plasma concentrations, a rapid increase in blood pressure may occur as circulating levels of such blockers decrease after hemodialysis. Thus, the effects of benidipine and nifedipine CR (extended-release coated tablets, Adalat CR), which are long-acting calcium channel blockers, on post-hemodialytic blood pressures were investigated.

METHODS

A randomized crossover trial was carried out with 10 hypertensive patients on chronic maintenance hemodialysis. Patients were assigned to receive benidipine (4-8 mg/day) or nifedipine CR (20-40 mg/day), and after 4 weeks, 24-hour ambulatory blood pressure monitoring was performed on the day of hemodialysis and blood samples were obtained before and after hemodialysis to measure plasma concentrations of the blockers. The calcium channel blockers were then exchanged in each patient and the same protocol was repeated.

RESULTS

The pattern of fluctuation of blood pressure differed markedly between the treatment with benidipine and nifedipine CR. Under treatment with nifedipine CR, rapid increase in blood pressure was observed after hemodialysis, while blood pressure remained at favorable levels with benidipine. Plasma concentrations of the blockers were significantly decreased by hemodialysis.

CONCLUSION

Benidipine exerts more sustained antihypertensive effects than expected from its disposition in plasma. The stable depressor effects of benidipine even after hemodialysis may contribute to favorable control of blood pressure in this population.