Relative bioavailability of two spray formulations of nitroglycerin

Twelve healthy male volunteers received two sublingual doses of 0.4-mg nitroglycerin from two metered-dose spray products, A and B. Plasma samples were collected immediately before and for up to 6 h following each dose. The samples were immediately extracted and analyzed for nitroglycerin. The results show striking differences between the two formulations. The mean AUC for preparation A, 159 +/- 66 h X pg/mL, was 2.7 times greater than for B, 59 +/- 33 h X pg/mL. The mean maximum plasma concentration for A was 1387 +/- 620 pg/mL which was 4.1 times greater than the mean maximum plasma concentration for preparation B (340 +/- 234 pg/mL). The time of maximum plasma concentration also occurred earlier for preparation A versus B, 4.3 +/- 1.6 versus 8.3 +/- 2.0 min, respectively. Such bioavailability differences may indicate therapeutic advantages for preparation A.