Drug receptor interactions Flashcards
(16 cards)
1
Q
What are cholinergic receptors (3)
A
- Key receptors in the autonomic nervous system
- Key role in regulating human physiology
- Regulated by acetylcholine (ACh)
2
Q
What are the types of cholinergic receptors (3)
A
- Nicotinic – respond to acetylcholine & nicotine
- Muscarinic – respond to acetylcholine & muscarine
- Both are activated by acetylcholine
3
Q
What are the types of natural ligands for cholinergic receptors (3)
A
- Acetylcholine
- Nicotine
- Muscarine
4
Q
What are other common ligands for cholinergic receptors (2)
A
- Butryrylcholine
- Methacholine
5
Q
What is the structure of acetylcholine (5)
A
- Positively charged quaternary nitrogen
- Carbon chain
- Ester link
- =O
- CH₃
6
Q
What is the structure of Nicotine (2)
A
- N-aromatic ring
- N-cyclopentane
7
Q
What is the structure of muscarine (2)
A
- cyclopentane with oxygen and OH
- Positively charged quaternary nitrogen
8
Q
What are nicotinic receptors (3)
A
- Coupled directly to ion channels
- When activated by ACh have an immediate response on nerve and muscle cells and the sensitivity of sensor cells
- Ion channels open in an ‘all or nothing’ fashion in between 0.1 and 10 milliseconds
9
Q
What are muscarinic receptors (3)
A
- Involved in maintaining homeostasis in humans
- ACh activation results in stimulation/inhibition of salivary, sweat glands, secretions and contractions of the gut, tonic action on smooth muscle, vasodilation, bronchial constriction
- Longer duration of action than nicotinic receptor
10
Q
What is acetylcholine chloride (4)
A
- Hydroscopic powder
- Formulated with mannitol
- Injected after being made up in sterile water
- Functions as a neurotransmitter, interacting with cholinergic receptors in the nervous system
11
Q
What functional groups are present in acetylcholine chloride (4)
A
- Quaternary ammonium ion: Provides a positive charge crucial for receptor binding.
- Ester group: Links the acetyl group to choline, making acetylcholine susceptible to rapid breakdown by acetylcholinesterase.
- Ethyl linkage: Connects the quaternary nitrogen and ester, providing spatial arrangement.
- Chloride ion: Balances the charge for stability in the salt form.
12
Q
What is cholinesterase (3)
A
- Metabolises acetylcholine
- This is an enzymatic acylation reaction at the carbonyl group involving a hydroxyl group from serine acting as a nucleophile
- The enzyme is restored by a hydrolysis reaction
13
Q
What is carbachol (2)
A
- Direct-acting cholinergic agonist
- Mimics the action of acetylcholine
14
Q
What is neostigmine (3)
A
- Indirect-acting cholinergic agent
- Inhibits acetylcholinesterase
- Increases the level of acetylcholine at cholinergic synapses.
15
Q
Between carbachol and neostigmine which is active orally and why (4)
A
- Neostigmine
- The phenyl ring stabilises the molecule
- tougher-to-break carbamate
- Carbachol is a small, simple molecule that’s easily attacked and degraded.
16
Q
What are the uses of neostigmine and carbachol (2)
A
- glaucoma
- myasthenia gravis
