Please enable JavaScript.
Coggle requires JavaScript to display documents.
PHARMACODYNAMICS(Drug/receptor interaction) - Coggle Diagram
PHARMACODYNAMICS(Drug/receptor interaction)
intro
study of the biochemical and physiologic effects of drugs
and their mechanisms of action
deals with the effects of drugs including the action effect sequence, dose effect relationship and modification of effect by other drugs or other factors :
drug action
main ways by which drugs act via interaction with cell proteins,namely receptors,ion channels,enzymes and carrierproteins
drugs can work by themselves mechanically or chemically
principles of drug action
stimulation-enhancement of the level of a specific biological activity
depression-diminution of the level of a specific biological activity
replacement-replacement of the natural hormones or enzymes which are deficient
cytotoxic action-toxic effects on invading microorganisms or cancer cells
receptor
a receptor is a protein which binds to a specific molecule
molecule it binds is known as the ligand
types
ligand gated ion channels example-cholinergic nicotinic receptors
g protein coupled receptors example-a and B adrenoreceptors
enzyme linked receptors example-insulin receptors
intracellular receptors example -steroid receptors
majority are proteins
epinephrine
B1 receptors in heart
B2 receptors in bronchioles
Agonist
when a drug binds to the receptor and activates it to produce an effect
inverse agonist-when a drug activates a receptor to produce an effect in the opposite direction to that of the agonist.will have affinity and negative intrinsic activity. ex flumazenil is an inverse agonist of benzodiazepine
partial agonist-when a drug binds to the receptor and activates it but produces a sub maximal effect.will have affinity but sub maximal intrinsic activity
example-ACh is agonist at muscarinic receptor in heart cell and will have both affinity and maximal intrinsic activity
affinity / intrinsic
affinity-it is the ability of a drug to bind to the receptor(just bind)
intrinsic activity-it is the ability of a drug to activate a receptor following receptor occupation
antagonist
a drug that binds to the receptor and blocks the effect of an agonist for that receptor
atropine is antagonist of ACh at muscarinic receptors will have only affinity but no intrinsic activity
efficacy and potency
efficacy is the maximal response produced by a drug (Emax),is a measure of how much drug is required to elicit a given response
potency is a measure of how much drug is required to elicit a given response, the lower the dose required to elicit given response, the more potent the drug is
therapeutic window
the dosage range between the minimum effective therapeutic concentration or dose, and the minimum toxic concentration or dose
ex theophylline has an average minimum plasma conc of 8mg/l and the toxic effects are observed at 18mg/l..the therapeutic window is 8-18mg/l
synergism and antagonism
action of one drug is facilitated by the other (synergism)
action of one drug may decrease or inhibit the action of other drug
receptop antagonism
when aa antagonist interferes with the binding of the agonist with its receptors and ihnibits the generation of a response
can be competitive and noncompetitive
tolerance
gradual reduction in response to drugs is called as tolerance