PS268 Chapter Notes - Chapter 5: Deltoid Muscle, Blood Vessel, Suppository
Routes of Administration:
3 basic routes:
1) Enteral
-oral administration or suppository (rectal/vaginal)
-even though oral intake is simplest way to take drug, absorption from gastrointestinal tract
is most complicated way to enter the bloodstream
-must withstand stomach acid and digestive enzymes and not be deactivated by food before
it is absorbed
-molecules must next get through the cells lining the wall and into blood capillaries
-if taken in capsule form, drug must dissolve and then, as a liquid, mix into contents of
stomach
-the more other material there is in the stomach, the greater the dilution of the drug/slower it
will be absorbed
-drug must be water soluble for the molecules to spread throughout the stomach but only
lipid-soluble and very small water-soluble molecules are readily absorbed into the
capillaries surrounding small intestine, where absorption into blood stream occurs
-if the drug is the type that is metabolized rapidly by the liver (ex nicotine), very little may
get into the general circulation thus nicotine is more effective when inhaled
-mucous membranes in rectum and vagina have a rich blood supply and drugs are absorbed
directly into the bloodstream, avoiding the gastrointestinal tracts
2) Parenteral (injection)
Document Summary
Even though oral intake is simplest way to take drug, absorption from gastrointestinal tract is most complicated way to enter the bloodstream. Must withstand stomach acid and digestive enzymes and not be deactivated by food before it is absorbed. Molecules must next get through the cells lining the wall and into blood capillaries. If taken in capsule form, drug must dissolve and then, as a liquid, mix into contents of stomach. The more other material there is in the stomach, the greater the dilution of the drug/slower it will be absorbed. Drug must be water soluble for the molecules to spread throughout the stomach but only lipid-soluble and very small water-soluble molecules are readily absorbed into the capillaries surrounding small intestine, where absorption into blood stream occurs. If the drug is the type that is metabolized rapidly by the liver (ex nicotine), very little may get into the general circulation thus nicotine is more effective when inhaled.
