[The acute and chronic effects of 10-mg nitroglycerin patches in stable angina of effort].

INTRODUCTION AND OBJECTIVES: To assess the anti-ischemic efficacy of nitroglycerin patches (10 mg/day), we studied, by means of serial exercise testing (Bruce protocol), 10 patients with stable effort angina in a randomized, placebo-controlled, cross-over, double-blind essay. METHODS: Patients were exercised 1, 4, 12 and 24 hours after a single patch, and 4 and 12 hours after a 48 hours therapy course. Chronic therapy was assessed after both continuous and intermittent (intermission of 12 hours) patch application. RESULTS: After single patch, time to angina and time to 1 mm ST depression were significantly increased with respect to placebo at 1-hour test (83 +/- 27 s and 119 +/- 39 s, respectively), 4-hour test (100 +/- 34 s and 87 +/- 29 s, respectively) and 12-hour test (46 +/- 15 s and 64 +/- 20 s, respectively). No effect was demonstrated at 24-hour test. After continuous treatment no differences with respect to placebo were found at any test. After intermittent treatment time to angina was prolonged (75 +/- 23 s) only at 4-hour test, and time to 1 mm ST depression at 4-hour test (61 +/- 19 s) and 12-hour test (41 +/- 14 s). CONCLUSIONS: Nitroglycerin patches improve parameters of exercise ischemia for a 12 hours period. Tolerance is developed very early and provokes absolute lack of efficacy. Tolerance can be avoided with intermittent patch application. No treatment schedule shows 24 hours efficacy.