[The acute and chronic effects of 50 mg of isosorbide 5-mononitrate with delayed action in patients with stable angina of effort].

: In 10 patients with stable effort angina and angiographically demonstrated coronary artery disease, serial exercise test were performed in order to assess the efficacy and duration of the anti-ischemic effects of a single dose (50 mg) of a sustained-release preparation of 5-isosorbide mononitrate (5-IMN). The possible presence of a tolerance phenomenon was also sought. The study was randomized, double-blind and placebo-controlled. Four hours after an acute dose of 5-IMN, time for -1 mm ST segment depression significatively increased as compared with basal test and placebo test (367 +/- 92 vs 199 +/- 87 and 250 +/- 78 sec respectively, p less than 0.0004). At the same test, total exercise time also increased from 282 +/- 92 sec (basal) and 323 +/- 91 sec (placebo) to 424 +/- 91 sec (p less than 0.008). At 12 hours test, total exercise time was also significantly increased as compared with basal test and placebo test (354 +/- 109 vs 282 +/- 92 and 291 +/- 90 sec respectively; p less than 0.01). These effects were not present when the patients were tested 24 hours after active drug administration. After daily administration of a single dose of 5-IMN during a 3 week period, 4 and 12 hours test demonstrated a persistent and significant anti-ischemic effect, similar to the acute figures. Thus, an acute dose of 50 mg of a sustained-release preparation of 5-IMN reveals significant anti-ischemic effects which remain 4 and 12 hours after drug administration. Chronic administration of the preparation for 3 weeks (single daily dose) is equally effective, without any evidence of tolerance phenomenon.