Pharmacology Flashcards
Agonist
A drug that binds to a receptors and initiates an intrinsic activity in the cell.
Agonist can be endogenous, like acetylcholine or synthesised
Antagonist
Drugs that blocks the effect of an agonist by causing no intrinsic activity.
It can be competitive: shaped similarly to the agonist and binds to the receptor.
Can be noncompetitive: Blocks receptors without binding to the receptor.
Competitive antagonist
Molecules shaped similarly to the agonist and binds to the receptor.
The effect of these antagonist can be overcome by increasing drug dosage to outcompete the antagonist for receptors.
Non-competitive antagonist
Drugs that block the effect of agonist by causing a permanent change to the receptors.
The drug binds to a site that the agonist does not bind to, to change the receptor function.
Increasing drug dosage cannot overcome the effect of a non-competitive antagonist.
ED50
The dose of drug required to produce half the maximum response- measure of potency
Emax
Maximum response a particular agonist can produce in a particular tissue .
β1-Adrenergic receptor
G-protein linked receptor located on the myocardium.
Increases cardiac output when activated by an agonist.
Gs is the G protein which activates adenylyl cyclase and increases cAMP production.
α1-Adrenergic receptor
G-protein coupled receptor that stimulates vasoconstriction when activated by adrenaline and noradrenaline.
Gq is the G protein used which stimulates the production of phospholipase C and IP3+DAG.
Rebound effect
Occurs when a symptoms arise even worse than before due to discontinuation of medication.
This happens because the medication used suppressed the use of the receptors so the body synthesised more receptors to overcome this.
When the medication is discontinued, there are even more receptors for the agonist causing the symptoms to act on.
Anti-histamines
Can be competitive or non-competitive antagonists that reduce the production of histamines.
Non-competitive antagonist require lower dosages to stimulate an effect.
Constitutively active receptors
Receptors that are are always active, despite the absence of an agonist.
Na+ ion channel blocker
Hydrophilic drugs that prevents the flow of Na+ into a cell.
The blockers prevents depolarisation of the cell, therefore inhibits the formation of action potential.
This prevents nervous transmissions.
These blockers can be used as anaesthetics and analgesics.
Beta-2 adrenergic receptors
G-protein coupled receptor located on respiratory, uterine, vascular smooth muscle, skeletal muscle and liver.
Activated by the agonist, adrenaline.
Stimulates vasodilation, bronchodilation and other muscle relaxation.
Gs is the G-protein that is used to activate adenylyl cyclase to produce cAMP from ATP.
cAMP activated protein kinase A which later leads to the relaxation of smooth muscle.
What receptors does the sympathetic system act on?
Adrenoceptors
Acetylcholine acts on nicotinic receptors in the adrenal glands which stimulate the release of adrenaline and noradrenaline.
Drugs used for common cold
Alpha agonist
Causes constriction of blood vessel in the nose and decreases its permeability- this acts as a decongestant.
The prevent this effect from happening to other important blood vessels that a nasal spray is used to its effect to only nasal blood vessels.
