First pass metabolism is significant problem in drug given through:
Ans. D, Directly into stomachAll orally administered dru.gs are exposed to drug metabolizing enzymes in the intestinal wall and liver (where they first reach through the poal vein).Drug given directly into the stomach and intestine still have to pass through first pass metabolism in the intestinal wall and in liver.Approximately 50% of the drug that it is absorbed from the rectum will bypass the liver, thus reducing the hepatic first-pass effect.Presystemic metabolism ln thc gut and liver can be avoided by administering the drug through sublingual, transdermal or parenteral (i. v/i.m/intradermal/s.c) routes.The event of first pass metabolism differs for dlfierent drugs and is an impoant datennlnant of oral bioavallabiltty.The hepatic first-pass effect can be avoided to a great extent by the use of sublingual tablets and transdermal preparations and to a lesser extent by the use oF rectal suppositories.Subltngu.al absorption provides direct access to systemic not poal-velns.The trans canal route ofiers the same advantage.
Sublingual route
Rectal route
Intramuscular route
Directly into stomach