[Biologic availability and hemodynamic actions following administration of sublingual glycerol trinitrate. A new...

Bioavailability and Hemodynamic Properties of Sublingually Applied Glyceryl Trinitrate/A new delivery system Bioavailability of glyceryl trinitrate (GTN, CAS 55-63-0) was investigated in 16 healthy subjects after sublingual application of 0.8 mg GTN from either a reference product (B) where GTN release is effected by fluorochlorohydrocarbon (FCH) or a test product (A) (Corangin Nitrospay) where GTN release is effected FCH-independently by a pumping system. Plasma concentrations of GTN and hemodynamic effects (digital plethysmography) were measured until 30 min after application. There was no significant difference (Wilcoxon's matched pairs signed rank test) in AUCo-t (A: 8.9 +/- 7.3 ng x h/ml; B: 8.3 +/- 7.6 ng x h/ml) and Cmax (A: 1.43 +/- 1.26 ng/ml; B: 1.13 +/- 1.06 ng/ml), but tmax was significantly shorter after application of the test product (A: 4.6 +/- 1.0 min; B: 6.7 +/- 2.7 min, p less than 0.01). Nonparametric confidence limits (90%) were 0.80-1.89 for AUCo-t (point estimator of the median 1.14), 0.92-2.78 for Cmax (point estimator 1.06) and 0.61-0.90 for tmax (point estimator 0.75). EC50-values obtained from the individual concentration/effect-curves were linked with the concentration/time-curves to establish the time of reaching EC50 (tEC50). GTN response did not differ for both preparations (EC50A: 0.25 +/- 0.24 ng/ml; EC50 B: 0.34 +/- 0.36 ng/ml), coincident with tmax, tEC50 was significantly shorter after administration of (A) (A: 1.8 +/- 0.3 min, B: 2.7 +/- 1.0 min). With respect to the variability of GTN pharmacokinetics, the test preparation shows superior bioavailability and a faster onset of hemodynamic action.