Isradipine therapy in chronic stable angina pectoris--comparison with nifedipine

Current available calcium antagonists, although useful in angina pectoris, are often poorly tolerated. We therefore compared isradipine, a new calcium antagonist, with nifedipine in 18 patients with angina. Patients sequentially received incremental doses of either isradipine (IS) 2.5-7.5 mg three times daily or nifedipine (NF) 10-30 mg three times daily for 6 weeks each, in a randomized double-blind crossover study. Both agents produced similar (P = 0.43) increases in maximum exercise duration (IS + 30%; NF + 34%) and an equivalent (P = 0.38) increase in time to onset of angina on exercise (IS + 53%; NF + 62%). Both IS and NF significantly reduced exercise-induced ST depression (-40% and -45%) to a similar degree (P = 0.48). NF significantly (P = 0.019) reduced angina attacks (-3.0 attacks.week-1; 26%) compared to IS (-0.4; 4%) whilst a similar but non-significant trend in favour of NF was also apparent in the consumption of sublingual glyceryl trinitrate (-0.1 tablets.week-1; 2% vs +1.3.week-1; 23%; P = 0.28). However, significantly (P less than 0.03) more patients experienced adverse events whilst taking NF than with IS (36 events in 16/18 (89%) v 18 in 9/18 (50%). Thus, IS and NF increased exercise tolerance and reduced exercise angina and ST depression equally well although NF use was associated with fewer anginal episodes and IS with fewer side effects.