[Transdermal nitroglycerin systems with continuous and discontinuous drug release. A comparison of the anti-ischemic...

The anti-ischaemic and haemodynamic effects of two transdermal nitroglycerin systems, each offering 15 mg of nitroglycerine, the first giving continuous release (group 1) and the other discontinuous release (group 2), were compared in 30 men (mean age 56.5 [33-70] years) with coronary heart disease confirmed by angiography. Resting and exercise haemodynamics together with the degree of exercise-induced ST segment depression were measured on the first day, before and two hours after application of the plaster. After one week's therapy these measurements were repeated 24 hours after the application of the plaster on the previous day and two hours after the last application. Two hours after the first application both groups showed significant reduction (P less than 0.01) in exercise-induced ST segment depression (group 1: -60%, group 2: -50%) and in mean pulmonary artery pressure during exercise (group 1: -10%; group 2: -7%). After one week's therapy the reduction in exercise-induced ST segment depression was still significant in group 1 (-60%; P less than 0.01), but in group 2 (-30%) it was no longer significant. After one week had passed there was no longer any significant reduction in mean pulmonary artery pressure in either group (group 1: -6%; group 2: 0%). The acute anti-ischaemic and haemodynamic efficacy of both transdermal nitroglycerin systems was hence comparable; however, the emergence of nitrate tolerance during long-term use was not prevented even by phased release of the drug.