Randomized crossover trial of isosorbide mononitrate (Elantan 20) and slow-release glyceryl trinitrate in the treatment of angina pectoris.

An open, randomized, comparative crossover clinical trial was carried out to compare the clinical efficacy of 20 mg isosorbide mononitrate 3-times daily and 6.4 mg sustained-release glyceryl trinitrate 3-times daily in the treatment of angina pectoris. Fifty patients entered the trial and 48 patients completed. Each treatment was given for 12 weeks followed by crossover to the alternative drug. Both treatments resulted in marked significant improvements relative to the pre-trial baseline, but isosorbide mononitrate was shown to be significantly (p less than 0.001) more efficacious than sustained-release glyceryl trinitrate in the reduction of the number of angina attacks and sub-lingual glyceryl trinitrate consumption. Angina frequency was lower with isosorbide mononitrate than with sustained-release glyceryl trinitrate in 33 (69%) of the patients, but lower with sustained-release glyceryl trinitrate than with isosorbide mononitrate in only 3 (6%) patients (p less than 0.001). Sub-lingual glyceryl trinitrate consumption was lower with isosorbide mononitrate than with sustained-release glyceryl trinitrate in 36 (75%) patients, but lower with sustained-release glyceryl trinitrate than with isosorbide mononitrate in only 5 (10%) patients. Examination of the effect of changing from isosorbide mononitrate to sustained-release glyceryl trinitrate therapy or vice versa confirmed the clinical superiority of isosorbide mononitrate. Physical exercise capacity was reported as improved in 20 (60%) patients with isosorbide mononitrate but in only 12 (25%) patients with sustained-release glyceryl trinitrate (p less than 0.02). Neither treatment showed any tendency for a reduction in effect during 12-weeks' continuous therapy.(ABSTRACT TRUNCATED AT 250 WORDS)