Bioavailability of D-propoxyphene, acetyl salicylic acid, and phenazone in a combination tablet (Doleron): interindividual variation and influence of food intake.

The influence of food intake on the bioavailability of three analgesic compounds--propoxyphene chloride, acetyl salicylic acid and phenazone--in a combination tablet, Doleron, has been examined in eight healthy volunteers. A single oral dose was given both on an empty stomach and together with a standardized breakfast meal. The plasma concentrations of propoxyphene, its major metabolite norpropoxyphene, salicylic acid and phenazone were determined by mass fragmentography, spectrofluorimetry and gas chromatography. Concomitant food intake had no consistent influence on the bioavailability of any of the components. Hence, doleron may be taken together with meals as well as between meals. Large interindividual variations in propoxyphene and phenazone concentrations were found, indicating that an optimal effect will not always be obtained by standard doses.