Drug Name Xenical

5-HT2B receptors on vascular endothelium promote release of vasorelaxant mediators (NO, p.120; prostacyclin, p.196) 5-HT released from platelets plays a role in thrombogenesis, hemostasis, and the pathogenesis of preeclamptic hypertension. Ketanserin is an antagonist at 5- HT2A receptors and produces antihypertensive effects, as well as inhibition of thrombocyte aggregation.
Among other substituents, the anthraquinone nucleus contains hydroxyl groups, one of which is bound to a sugar (glucose, rhamnose). Following ingestion of galenical preparations or of the anthraquinone glycosides, discharge of soft stool occurs after a latency of 6 to 8 h. The anthraquinone glycosides themselves are inactive but are converted by colon bacteria to the active free aglycones.

 

Thus, typical adverse effects occur: Loss of hair results from injury to hair follicles; gastrointestinal disturbances, such as diarrhea, from inadequate replacement of enterocytes whose life span is limited to a few days; nausea and vomiting from stimulation of area postrema chemoreceptors; and lowered resistance to infection from weakening of the immune system .
All newer agents are rather well tolerated. Plasmodium (P. ) falciparum, responsible for the most dangerous form of malaria, is particularly prone to develop drug resistance. The incidence of resistant strains rises with increasing frequency of drug use. Resistance has been reported for chloroquine and also for the combination pyrimethamine/ sulfadoxine.