Agonists Flashcards
What is an agonist?
Drugs that bind to a receptor to produce a biological response similar to that produced by the endogenous ligand for the receptor
What id the word efficacy used for?
Describing that a drug has an effect
What is carbachol?
A synthetic drug with a structure similar to that of acetylcholine, it is a cholinergic agonist
What is phenylephrine?
A synthetic drug that resembles noradrenaline, binds to a1-adrenoreceptors
What receptor does heroin bind to?
Opioid
What are antagonists?
Drugs which decrease the biological response to an agonist drug or endogenous ligand.
What does the most common antagonist produce?
Reversible competitive antagonism, compete for binding site
What is atropine?
A reversible competitive antagonist of the neurotransmitter acetylcholine, blocks the effects of the agonist drug carbachol.
What is propranolol?
B-blocker, reversible competitive antagonist of noradrenaline.
What us acetylcholine?
An agonist
What is the antagonist for acetylcholine esterase?
Neostigmine
What is the preganglionic receptor for acetylcholine?
Nicotinic
What is the postganglionic receptor for acetylcholine?
Muscarinic
Give two types if antagonists which will only block one type of receptor
- Hexamethonium
2. Atropine
What is noradrenaline?
An agonist which is the predominant agonist released at target tissues. A catecholamine like dopamine and adrenaline
What is adrenaline?
Similar to noradrenaline, released following sympathetic stimulation of the adrenal gland. Enters circulation
What are the receptors for adrenaline and noradrenaline?
Subset of the family of G protein-coupled receptors called adrenoreceptors (adrenergic receptors)
What are the 3 major branches of the adrenoceptor family?
alpha 1, alpha 2 and beta
Which group of adrenoceptors does phenylephrine beling to?
Alpha1
How is phenylephrine different to noradrenaline?
Missing a hydroxyl group which would be used to activate a beta-receptor
What does activation of alpha 1 result in?
Contraction of vascular smooth muscle
What are the antagonists which will block alpha 1 receptors?
Prazoisin
Phentolamine
Give a classic agonist of alpha2 receptors
Clonidine
Give two classic agonists of beta receptors
Isoprenaline and salbutamol