Is bisacodyl absorbed at all from suppositories in man?

A HPLC procedure was developed to determine free BHPM in human plasma and urine after prior deconjugation of its glucuronides with glucuronidase. A single dose administration of a 10 mg bisacodyl suppository from Glaxo Wellcome, Poznań (Poland) to 16 volunteers each resulted in its low active metabolite (BHPM) plasma levels (10-55 microgram l(-1)) according to general assumptions. Its prompt laxative effect appeared within 56.6+/-10.8 min. The calculated serum half-life time of BHPM glucuronide excretion in urine was approximately 7.32+/-0.99 h. BHPM was excreted in urine in only 3. 36+/-0.52% if compared with the above bisacodyl rectal dose administered. Any relationship between BHPM plasma and/or urine levels and its laxative action does not occur. These results confirm the thesis that the laxative action of bisacodyl suppositories is initiated through a direct interaction of the drug in the rectum.