DRUG ADMINISTRATION & ABSORPTION Flashcards
Wh at are the 4 main processes of pharmacokinetics?
Absorption, distribution, metabolism, elimination/excretion
What are the 3 routes of drug administration?
Topical, parenteral, enteral
Examples of topicals:
- skin
-inhalers
-eye and ear drops
Examples of enteral:
-oral
-rectal
Examples of parenteral:
-intravenous (in the vein, quicker, bypasses absorption)
-subcutaneous (under the skin)
-intramuscular (into muscle)
-transdermal (through skin)
-intrathecal( into spine)
-sublingual (under tongue)
Medication goes straight into the bloodstream
Process of oral drug administration:
Stomach, portal vein, liver, systemic circulation, target tissue, target cell
What is drug absorption?
Movement of a drug from its site of administration body across membranes, and circulating fluids (bloodstream).
Drugs must first dissolve (seperate from the excipient) in stomach and/or intestinal fluids which are largely composed of water
What must happen for a drug to dissolve?
MUST be in water!!!
What must happen for a drug to get in the bloodstream?
MUST dissolve in lipids (fat)!!!
All drugs must be ________, although they can be ________ IF they are taken with food.
- SOLUBLE
- NON-SOLUBLE
What do biological fluids consist mainly of?
Water, polar environment
Orally administered drugs are bound to excipients that add bulk to the tablet, but also can:
- enhance the rate of dissolution
- slow the rate of dissolution
- alter hepatic enzymes (first pass effect)
A drug cannot be absorbed until it is:
Free of excipients, it must be dissolved first
If a drug is water soluble (polar), can it be administered IV ?
YES
- since IV administration skips the process of absorption, a fast onset of action is expected
What is passive diffusion?
- most common mechanism
- movement is dictated by the concentration gradient
- move from a high to low concentration gradient until equilibrium is reached
- drugs must be small in size an lipid soluble to pass through biological membrane via diffusion