Review of Pharm Principles Flashcards
Pharmacodynamics
- mechanism of action
- receptors and receptor sites
- therapeutic range and toxic index
Pharmacokinetics
- Absorption (permeability, Henderson-Hasselback, pka)
- Distribution (Vd)
- Metabolism or Redistribution
- Excretion
Therapeutic Index
the ratio between the toxic TD50 and effective dose ED50
Drug efficacy
ability to produce an effect
Drug Potency
the amount of drug required to produce the desired response
Enantiomers
isomers that are mirror images of each other (ex. a right hand and a left hand)
-chemically identical, but aren’t pharmacologically equal.
-when they are present in equal proportions they are referred to as a racemic mixture
Drug Clearance =
= rate of elimination of drug/ plasma drug concentration
Clearance by an organ = (the extraction capability of the organ) x (the blood flow to the organ)
Zero Order kinetics
regardless of drug concentration, a constant amount of drug is metabolized per unit of time
First Order Kinetics
a constant percentage of drug is metabolized per unit time proportional to plasma drug concentraion
Phase I Reactions
oxidation, reduction, hydrolysis
-includes p450 enzymes
Phase II reactions
conjugation: glucuronidation, acetylation, etc.
Solubility of ionized vs non-ionized drugs?
Ionized forms of a drug are charged and are water-soluble.
Nonionized forms of a drug do not have an electrical charge and are lipid-soluble.
Context sensitive half time (CSHT)
Time necessary for the plasma drug concentration to decrease by 50% after discontinuing a continuous infusion of a specific duration
-longer infusions, more drugs accumulate into tissues (depending on Vd), which increases duration of action
Henderson-Hasselbalch equation
The acid dissociation equilibrium equation.
p.H. = p.K.a. + log[A-]/[HA]
A- = proton acceptor HA = proton donor
-predicts what portion of a solution is ionized vs non-ionized
Weak acids are more _________ (ionized/non-ionized) in an acidic solution
non-ionized a.k.a. better absorption and distribution
Think: you are adding an A-H to a solution that has a surplus of H+ ions [an acidic solution] so it won’t want to give up it’s hydrogen into solution and become A- minus [ionized]
