Gas chromatographic determination of propoxyphene and norpropoxyphene in plasma.

Propoxyphene and its major metabolite norpropoxyphene have been determined simultaneously by using gas chromatography. In order to avoid the on-column decomposition of the propoxyphene, derivatives were formed with the aid of lithium aluminium hydride, which cleaves the propionic acid ester of propoxyphene and reduces the norpropoxyphene amide. Promethazine was used as an internal standard. Propoxyphene and norpropoxyphene levels in plasma were determined in samples from six male volunteers receiving a single oral dose of 150 mg of propoxyphene hydrochloride in a sustained-release form (Abalgin Retard).