Examples of drugs administered rectally in the form of suppositories for their systemic effects include a) prochlorperazine(丙氯拉嗪)and chlorpromazine(氯丙嗪) b) oxymorphone Hcl(盐酸羟吗啡酮) e) ergotamine tartrate(麦角胺酒石酸盐) Indomethacin e) ondansetron
Examples of drugs administered rectally in the form of suppositories for their systemic effects include a) prochlorperazine （丙氯拉嗪）and chlorpromazine（氯丙嗪） b) oxymorphone HCl （盐酸羟吗啡酮） c) ergotamine tartrate（麦角胺酒石酸盐） d) indomethacin e) ondansetron
2. Some factors of drug absorption from rectal suppositories 1)Physiologic factors ■ Colonic content when deemed desirable. an evacuant enema may be administered and allowed to act before the administration of a suppository of a drug to be absorbed Diarrhea, colonic obstruction, and tissue dehydration
2. Some factors of drug absorption from rectal suppositories 1) Physiologic factors ◼ Colonic content - when deemed desirable, an evacuant enema may be administered and allowed to act before the administration of a suppository of a drug to be absorbed. - Diarrhea, colonic obstruction, and tissue dehydration
Circulation route The lower hemorrhoidal veins surrounding the colon receive the absorbed drug and initiate its circulation throughout the body bypass the liver Lymphatic circulation also assists in the absorption of rectally administered drugs
◼ Circulation route - The lower hemorrhoidal veins surrounding the colon receive the absorbed drug and initiate its circulation throughout the body, bypass the liver. - Lymphatic circulation also assists in the absorption of rectally administered drugs
pH and lack of buffering Because rectal fluids are essentially neutral in ph and have no effective buffer capacity the form in which the drug is administered will not generally be chemically changed b the rectal environment The suppository base employed has a marked influence on the release of active constituents incorporated into it
◼ pH and lack of buffering - Because rectal fluids are essentially neutral in pH and have no effective buffer capacity, the form in which the drug is administered will not generally be chemically changed by the rectal environment. - The suppository base employed has a marked influence on the release of active constituents incorporated into it
2)Physicochemical factors of the drug and suppository base Lipid-water solubility A lipophilic drug that is distributed in a fatty suppository base in low concentration has less of a tendency to escape to the surrounding aqueous fluids than would a hydrophilic substance present in a fatty base to an extent approaching its saturation
2) Physicochemical factors of the drug and suppository base ◼ Lipid-water solubility - A lipophilic drug that is distributed in a fatty suppository base in low concentration has less of a tendency to escape to the surrounding aqueous fluids than would a hydrophilic substance present in a fatty base to an extent approaching its saturation