Pharma Flashcards
Absorption is total only for what form of admin
Intravenous
What is bioavailability
measure of how much drug reaches the circulatory sys and is available at the site of action
In order for a drug to be well absorbed, it has to be
largely hydrophobic
What factors influence bioavailability
ROA Degradation of drug prior to absorption GI absorption mechanisms Solubility Hepatic first pass Drug chemistry
What is drug distribution
the ability of a drug to move from the circulatory sys into the interstitial and tissues.
What factors affect drug distribution
Blood flow
Protein binding
Permeability; think blood brain barrier.
What is volume of distribution
Theoretical amount of fluid the drug is dispersed in after administration.
VD= total amount of drug in the body/blood concentration of drug
What are phase I reactions
Converts molecules into often still active slightly polar water soluble, metabolites though redox or hydrolysis reactions. e.g. cytochrome p-450
What are phase II reactions
Converts metabolites into inactive polar metabolites via acetylation, glucoronidation or sulfation that are then excreted by the kidneys
What is zero-order elimination
elimination of drug on a liner constant regardless of concentration.
Ex: Alcohol, phenytoin, aspirin
What is first-order elimination
Elimination of drugs in a proportional fashion to drug concentration. Concentration will decrease exponentially with time.
Competitive Antagonists shift the agonists curve in which direction
to the right
Noncompetitive antagonists shift agonist’s curve in which direction
downward
