Efonidipine, a calcium antagonist with activity that "sharply
contrasts" with other drugs in this class, appears to preserve renal
function in hypertensive patients with renal impairment, Japanese
researchers report.

In the February issue of the American Journal of Hypertension, Dr.
Koichi Hayashi and colleagues from Keio University, Tokyo, note that
whereas traditional calcium blockers preferentially act on afferent
arterioles, efonidipine has the ability to dilate "both afferent and
efferent arterioles." This characteristic "may produce marked effect
on renal injury."

To investigate, Dr. Hayashi's team compared the effects of
efonidipine and ACE inhibitors on blood pressure and proteinuria in
68 hypertensive patients with renal impairment or chronic renal
parenchymal disease. During the 48-week study, 23 patients were
randomly assigned to receive efonidipine and 20 to receive ACE
inhibitors.

Systolic blood pressure was reduced from 161 mm Hg to 142 mm Hg with
efonidipine, and from 163 mm Hg to 141 mm Hg with ACE inhibitor
therapy. Baseline creatinine clearance was maintained at 48 weeks in
both groups of patients.

"Proteinuria tended to decrease in both groups, and a significant
reduction was observed in proteinuric patients (greater than 1 g/day)
(efonidipine, from 2.7 to 2.1 g/day; ACE inhibitor, from 3.0 to 2.0
g/day)," Dr. Hayashi and colleagues report. Unlike ACE inhibitors,
efonidipine decreased proteinuria in proteinuric patients who did not
exhibit decreases in systemic blood pressure.

The team notes that 43.3% of patients treated with ACE inhibitors
experienced adverse effects, compared with 10.5% (p < 0.05) of those
treated with efonidipine. Adverse events included hyperkalemia and
nonproductive cough.

They conclude that the therapeutic efficacy and safety profile of
efonidipine "may favor the use of this agent in the treatment of
hypertension with renal impairment."

Am J Hypertens 2003;16:116-122