Determination of propoxyphene and norpropoxyphene by chemical ionization mass fragmentography.

The kinetics of propoxyphene and its primary metabolite, norpropoxyphene, have been simultaneously re-evaluated in man by using gas-liquid chromatography/mass spectrometry, deuterium-labeled mass internal standards, and multiple ion monitoring. Plasma concentrations in 4 volunteers determined for as long as 240 hr after single oral doses of 2 propoxyphene salts indicate the overall half-life of propoxyphene to be 11.8 hr and of norpropoxyphene to be 36.6 hr.