Pharmacodynamics Flashcards
Definition of pharmacodynamics
effects of drugs on the body; drug receptors, dose-response curves, mechanisms of drug actions
Definition of receptor
specific molecule in a biological system that plays a regulatory role
Definition of ligand
molecule that binds to a receptor
Emax
maximal effect that can be produced by drug
ED50
dose of drug that produces 50% of its maximal effect
Graded dose-response curve is used for…
measuring the magnitude of a response with given doses, typically represents the mean value within a population or single subject
Quantal dose-response curve is used for…
determining if the “response” occurs, requires a pre-defined response
Non-cumulative quantal dose response curve
number or % of individuals responding at a dose of a drug and only at that dose
Cumulative quantal dose response curve
number or % of individuals responding at a dose of a drug AND at all doses lower than that dose
TD50
median toxic dose
LD50
median lethal dose
Therapeutic index
TD50/ED50
Therapeutic window definition
range of doses of a drug or of its concentration in a bodily system that provides for the safe and effective therapy
Potency
describes amount of drug required to produce a specific pharmacological effect; represented by ED50
Efficacy
maximal pharmacological effect a drug can produce, represented by Emax, related to total number of receptors available to bind a drug
Parameters that describe the interaction of a drug with a receptor
binding, affinity, selectivity, intrinsic activity
Covalent bond in drug-receptor binding
irreversible, requires drug removal and receptor activation requires re-synthesis of receptor or enzymatic removal of the drug
Non-covalent bonds in drug-receptor binding
reversible, most drugs bind to receptors via non-covalent bonds
Affinity
how readily and tightly the drug will bind to the receptor
Bmax
maximal binding
Kd
equilibrium dissociation constant, drug concentration at which 50% of the drug receptor binding sites are occupied by the drug
Kd/affinity relationship
lower Kd, higher affinity; higher Kd, lower affinity