A PHARMACOKINETIC STUDY OF SUBLINGUAL AEROSOLIZED MORPHINE IN HEALTHY-VOLUNTEERS

A pharmacokinetic study was undertaken to compare the pharmacokinetics of morphine after an intravenous dose with the pharmacokinetics after a sublingual dose administered from an aerosol. Plasma levels of morp hine, morphine-3-glucuronide and morphine-6-glucuronide were measured in five normal volunteers after morphine administration by the intrave nous route and from a novel sublingual pressurized aerosol formulation . The mean (+/- s.d.) bioavailability of the sublingual aerosol morphi ne was 19.7 +/- 6.7 %. The morphine-3-glucuronide/morphine and the mor phine-6-glucuronide/morphine ratios were 5.1 +/- 1.6 and 1.2 +/- 0.4, respectively, for the intravenous route and 28.3 +/- 11.3 and 5.2 +/- 1.4, respectively, for the sublingual route. The combined total areas under the plots of systemic concentration against time (AUC) for the m etabolites after the two routes was not significantly different. When compared with published data for oral administration the results demon strate that the sublingual aerosol morphine might provide an alternati ve to conventional methods of morphine delivery, and has similar pharm acokinetics to a sublingual morphine tablet. It has no particular phar macokinetic advantages over oral morphine, except a potential for a fa ster onset of analgesia. Bioavailability, maximum plasma concentration , Cp(max), and the time at which the maximum plasma concentration is r eached, T-max, are equivalent to those for orally administered morphin e.