Isradipine, a 1,4 dihydropyridine calcium channel antagonist, is a potent 
coronary artery dilator that increases coronary blood flow with little effect on 
cardiac contractility. Isradipine is an approved antihypertensive agent, but its 
antianginal effects have not been well documented. In this placebo-controlled, 
double-blind, parallel-group design study we evaluated the duration of effects 
and safety of isradipine 10 mg bid in male patients with chronic stable angina 
pectoris. Seventy-two patients experiencing moderately severe angina between 3 
and 7.5 minutes during a standard Bruce exercise test received placebo in a 
single-blind manner for 8-14 days. Sixty-one of these patients had reproducible 
treadmill exercise test results on three consecutive occasions and underwent 
further exercise tests at 3, 8, and 12 hours after a placebo period. Patients 
were then randomized (double blind) to either placebo or isradipine 10 mg bid 
for 2 weeks. Symptom-limited exercise tests were repeated predose and at 3, 8, 
and 12 hours after the 0800 hour dose dosing. Exercise duration increased 
significantly from baseline (last qualifying test during the single-blind 
placebo therapy, i.e., 0800 hours predose at visit 4) in the isradipine group 
compared to the placebo group prior to the administration of the 0800 hour dose 
(i.e., 12 hours after the 2000 hour dose) by 51 vs. 18 seconds, p = 0.04; and 
after the administration of the 0800 hour dose at 3 hours by 78 vs. 29 seconds, 
p = 0.005; and at 8 hours by 54 vs. 18 seconds, p = 0.04. Similarly, statistical 
significance was achieved when exercise data were analyzed using visit 4 
(single-blind placebo therapy) corresponding time points as baseline. At 12 
hours after the 0800 hour dose, exercise tolerance did not increase 
significantly after isradipine compared to placebo. Time to 1-mm ST-segment 
depression increased significantly after isradipine at 3 hours post 0800 hour 
dose compared to placebo (87 vs. 7 seconds, p < 0.01) but not at the 0, 8, or 
12-hour postdose time points, regardless of which baseline was used. Isradipine 
therapy did not affect the rate-pressure double product. A significant 
correlation between the mean increase in total exercise time and mean plasma 
isradipine concentration was also present (p = 0.0295). During double-blind 
treatment, drug-related adverse events were experienced by four patients in the 
isradipine group and two patients in the placebo group. None of the patients 
experienced ischemic complications during the study.(ABSTRACT TRUNCATED AT 400 
WORDS)