Plasma levels and urinary elimination of diftalone, paracetamol, and their metabolites after single oral administration in man.

The plasma levels of diftalone, its metabolite 7-hydroxydiftalone, unconjugated and total paracetamol have been assessed in 6 healthy volunteers after oral administration of diftalone 0.75 g and of paracetamol 1.0 g, given alone and in combination in a cross-over fashion. In the same subject the urinary elimination of 7-hydroxydiftalone, and of unconjugated and total paracetamol has also been estimated. The results provide some indication of a slight increase in the plasma levels of unconjugated and total paracetamol, when the drug is administered in combination with diftalone. The increase, however, does not reach the significance level. As to diftalone and its metabolite, the differences between the plasma levels obtained after administration of the compound alone and those obtained when it was given in combination were negligible. Furthermore, the urinary recoveries of 7-hydroxydiftalone and of unconjugated and total paracetamol were very similar after administration of each compound alone and of their combination. It is concluded that the administration of single doses of diftalone and paracetamol in combination does not produce any pharmacokinetic interaction likely to be of clinical relevance.