Comparative bioavailability of a morphine suppository given rectally and in a colostomy.

In eight patients with a colostomy, plasma morphine levels were followed for 8 h after administration of 20 mg morphine chloride as a suppository, first rectally and after at least 48 h via the colostomy. The bioavailability after administration in the colostomy showed very great variation; the mean value compared to rectal bioavailability was only 43% (range 0.1-127%). In four patients the plasma concentrations of morphine after colostomy administration were lower at all times than after rectal administration, and in three only small amounts of morphine were detectable. One patient showed higher plasma concentrations after colostomy application than after rectal administration. It is concluded that administration of morphine suppositories in a colostomy cannot be recommended.