Effects of short- and long-term treatment with transdermally and orally administered nitroglycerin (a double-blind crossover study).

The efficacy of a once daily transdermally applied nitroglycerin system and of sustained release nitroglycerin capsules was assessed by ergometer stress testing in 12 patients with stable angina pectoris in a double-blind crossover study. In the morning the patients received transdermally applied nitroglycerin (TDS) which delivered 5.0 mg nitroglycerin in 24 hours together with a placebo capsule, respectively 1 nitroglycerin (NTR) capsule of 2.5 mg together with a plaster placebo. In the evening the first treatment group received 2 placebo capsules, and the second group 1 NTR capsule and 1 placebo capsule. Each period lasted 14 days. The patients performed a pre-medication ergometer stress test and repeated the test on the first and 14th day of each treatment period, 1 and 24 hours after medication. At the end of the second period all patients continued in an open study with TDS once a day for a further three months. Minor degrees of ST-segment depression, and in fewer patients, were observed at comparable workloads in the treatment tests compared with the pre-medication tests. The improvement after TDS on the first and last day of each period, 1 and 24 hours after medication, was significant and more marked than with NTR. The latter did not reach significance. Furthermore, increase of work capacity and elevation of angina threshold was greater with TDS than with NTR. Similar results were found at the end of the open study after 3 months' treatment with TDS. No development of tolerance was observed.