COMPARISON OF THE EFFECTS OF 2 DIFFERENT GALENICAL PREPARATIONS OF GLYCERYL TRINITRATE ON PULMONARY-ARTERY PRESSURE AND ON THE FINGER PULSECURVE

The time course and the magnitude of the effect of glyceryl trinitrate (GTN) on central venous (pulmonary artery diastolic pressure - PAP(d) ) and peripheral arterial (a/b-ratio of the finger pulse wave) haemody namics were compared in a randomized double-blind cross-over study in 12 patients suffering from congestive heart failure (NYHA II-III) with elevated PAP(d) at rest (greater-than-or-equal-to 15 mm Hg). The data were obtained in a bioavailability study of two sprays of glyceryl tr initrate, which differed in their galenical characteristics and in the dose of GTN (0.4 mg vs. 0.8 mg). Following sublingual administration of each spray, PAP(d), a/b-ratio and the plasma concentrations of GTN and its metabolites were measured up to 30 min. The relative bioavaila bility of GTN of the test preparation was estimated to be 157 %,161 % and 147 %, when calculated from the plasma concentration-time data or the integrated effect of GTN on a/b-ratio or PAP(d), respectively. The mean time courses of the decrease in PAP(d) and the increase in the a /b-ratio of the finger pulse curve were mirror images. Thus, there was a strong correlation between the mean values of PAP(d) and a/b-ratio following the administration of glyceryl trinitrate. Since the slope o f the relationship differed considerably between the patients, the mag nitude of effect of GTN on PAP(d) in the individual patient could not be predicted from the changes in a/b-ratio.