Pharmacology Lecture 4_Intro to Pharmacodynamics Flashcards
Define Potency
Potency is the messure of how much dose is required to achieve a desired effect. example drugs X and Y can achieve Emax. drug X reaches Emax at 70 mg/kg while drug Y reaches Emax at 100mg.kg thus drug X is more potent
Define Lethal dose 50 (LD50)
Historically the LD 50 is the dose that is lethal to 50% of a population. The definition has been expanded to include addverse affects other than death
Define Therapudic Index (TI)
TI = LD50/ED50. a higher TI means the LD50 is greater than the ED50 and thus it is harder to over dose a drug
Define relative safety
Relative safety is basically looking at TI. A drug with a higher TI is relativly safer than a drug with a lower TI
Define Synergistic effect
When two drugs with similar effects have a disproportional response when taken together
Define additive effect
When two different drugs with similar effects have a preportional response when they are taken together
Define Tachyphylaxis effect
sudden reduced response to a drug shortly after initial exposure
Define Maximal Efficacy (Emax)
Emax is a 100% effect of a desired outcome, ie total pain relief
Define Effective dose 50 (ED50)
The ED 50 is the dose that gives half of a population a therapeutic response
Define tolerance
Tolerance is when extended exposure to an agonist causes a cell to down regulate it’s receptor population
Define sensitivity
Sensitivity is when exposure of an antagonist causes a cell to upregulate its receptor population
Define Effacicy
Effacicy is a messure of the percentage of a desired outcome that can be acheived by a drug. Example Morphine can reach the Emax for pain relief (ie 100% pain relief) while asprin cannot achieve total pain relief. Thus morphine is more efficatious
