Some factors drug absorption agents from rectal suppositories
Introduction:
The length of the rectum is 150 mm, and the surface area is about 0.02-0.04 square meters (noting that the surface area of the small intestine is 200 square meters) , in the absence of stool, the rectum contains 3 mm of fluid.
Factors affecting the rectal absorption of the drugs ( physiologically factors ):
A) Colonic content: to increase the absorption of the drug from the colon, the colon must be empty this may help the drug contact the surface of the colon.
B) Circulation route: The veins of the lower hemorrhoids surrounding the colon that absorb and receive the drug and then pass it on to the liver (when using systemic rectal suppositories).
C) The effect of pH on drug absorption: The pH value of the colon in the normal state is 6.8, and this value is changed when the drug is absorbed so that the drug that has weak acids and bases is absorbed faster in the colon than strong acids and bases (and the reason is due to the fact that drugs with strong acids and bases have high ionization), and ionization It affects the speed of absorption because it is natural that the colon is in a state of unioniztion, so drugs with weak bases and acids are absorbed faster through the colon. Also, acidic drugs can increase absorption when the pH surrounding the colon decreases.