THE ABSORPTION AND EXCRETION OF PENTAZOCINE AFTER ADMINISTRATION BY DIFFERENT ROUTES

Abstract

Some of the factors affecting the absorption and metabolism of drugs are briefly reviewed and the absorption and excretion of pentazocine after administration by different routes to four healthy non-smoking male volunteers is described. Significant intersubject variations were found but the intrasubject variations were small and, regardless of the route of administration, a consistent pattern of relative rates of metabolism was demonstrated. Data are presented showing blood levels and urinary excretion of pentazocine throughout each study. Pentazocine was well absorbed by all the common routes of administration and the rate of metabolism seemed to be the factor which controlled the blood levels achieved. Faecal excretion was negligible, being less than 2 per cent of the administered dose over the first 48 hours. Clinical application of this information is possible and it is hoped that studies such as this can be useful in providing greater therapeutic efficiency and a reduction in side effects.