Angina pectoris is one of the major syndromes against which to test the therapeutic effectiveness of any new calcium antagonist. An interim analysis of the efficacy and safety of a new dihydropyridine calcium antagonist (PN 200-110 [isradipine]) in patients with confirmed coronary artery disease is reported. The study was carried out in 3 centers; 50 patients of an anticipated 96 have completed the double-blind comparative phases in 3 separate studies. Preliminary results from the placebo-controlled study indicate that PN 200-110 was significantly more effective than placebo in reducing the anginal attack rate and glyceryl trinitrate consumption in the 15 patients so far enrolled. Dose-response comparisons against nifedipine in 21 patients and against isosorbide dinitrate in 14 patients demonstrate that PN 200-110 has a similar antianginal efficacy profile to both drugs. No significant change in any of the monitored safety factors was noted in any of the patients taking PN 200-110. The side-effects profile compared favorably with that of nifedipine. These interim results suggest that PN 200-110 will prove to be an effective and safe drug for the treatment of angina pectoris.