cholinergic drugs Flashcards
What are cholinomimetics?
Drugs that mimic the action of acetylcholine (ACh)
Cholinomimetics include direct receptor agonists and indirect acting AChE inhibitors.
What are the two categories of cholinomimetics?
- Direct (receptor agonists)
- Indirect (AChE inhibitors)
What is the effect of cholinergic antagonists?
Reduce the action of acetylcholine (ACh)
Cholinergic antagonists can be further classified into antimuscarinic and antinicotinic.
What direct acting agonists are susceptible to AChE?
Acetylcholine
What are the 2 classes of cholinergic antagonists?
- antimuscarinic
- antinicotinic.
What are the characteristics of indirect acting agonists?
They are AChE inhibitors that increase local ACh concentration by reducing hydrolysis.
What is the duration of action for reversible AChE inhibitors like physostigmine?
intermediate-acting
What is the duration of action for AChE inhibitor, physostigmine?
30min - 6h (intermediate-acting)
What is the duration of action for AChE inhibitor, echothiophate?
long-acting
What is the mechanism of irreversible AChE inhibitors?
Covalent bond formation with AChE, stabilizing the bond
Examples include organophosphates like echothiophate.
What are the symptoms of muscarinic excess?
- Diarrhea
- Urination
- Miosis
- Bradycardia
- Bronchoconstriction
- Excitation (CNS)
- Lacrimation
- Sweating and salivation
What is the fatal dose of nicotine?
40 mg, approximately 2 cigarettes
What is the primary effect of nicotine on the nervous system?
Activates both the PSNS and SNS (Nn) at ganglia, whoch increases release of ACh and NE in tissue and adrenal gland
What is the role of atropine in organophosphate poisoning?
Atropine is used to block muscarinic effects and has equal affinity for M receptor subtypes.
What type of drug is trimethaphan?
Ganglionic blocker
What are the effects of pilocarpine in the eye?
Reduces intraocular pressure, used to treat glaucoma
Fill in the blank: Most cholinergic receptor agonists used clinically are not receptor subtype _______.
selective
True or False: Muscarinic receptor activation leads to vasodilation.
True
What is the primary action of AChE inhibitors?
Increase ACh levels at synapses
What are the two types of cholinergic receptors?
- Muscarinic
- Nicotinic
What neurotransmitter is primarily released by the PSNS?
Acetylcholine (ACh)
What are the main effects of nicotine on the cardiovascular system?
- muscarinic excess
- CNS induced convulsions/coma/respiratory depression
- skeletal muscle contraction followed by paralysis
- Increased heart rate and blood pressure
What are the effects of ACh at ganglia in the PSNS?
Increased ACh levels
What is the effect of organophosphates on the nervous system?
Initial symptoms of muscarinic excess followed by CNS stimulation Nn and Nm activation)
What is the pharmacokinetics of atropine?
Well absorbed and distributed, half-life of 2 hours
What is the historical significance of Atropa Belladonna?
Used in the Italian renaissance for dilating pupils, considered beautiful
(Plant version of Atropine)
What are antinicotine drugs?
Antinicotine drugs inhibit the effect of ACh at specific sites.
They include ganglionic blockers and neuromuscular blockers.
What is an example of a ganglionic blocker?
Trimethaphan
It can be used for hypertensive crisis or dissecting aortic aneurysm.
What kind of drug is D-Tubocurarine? What is it used for?
- A neuromuscular blocker
- Use to reduce skeletal muscle contraction in surgical procedures.
It is a neuromuscular blocker.
What condition is characterized by increased ocular pressure?
Glaucoma
It is a condition that can lead to vision loss if untreated.
Which drugs are used to treat glaucoma?
Pilocarpine, physostigmine, echothiophate
These drugs help decrease ocular pressure.
How do pilocarpine and physostigmine differ in their mechanism of action?
Pilocarpine primarily stimulates muscarinic receptors while physostigmine inhibits acetylcholinesterase.
This leads to different physiological effects.
The PNS releases ____ at the ganglion, and ____ at the neuroeffector junction. This activates ____ receptors.
ACh, ACh, M2/M3
The SNS releases ____ at the ganglion, and ____ at the neuroeffector junction. This activates ____ receptors.
ACh, NE, a1/b1/b2
The PSNS is made up of 2 axons: a ____ pregalglionic axon, and a ____ postganglionic axon.
cholinergic, cholinergic
The SNS is made up of 2 axons: a ____ pregalglionic axon, and a ____ postganglionic axon.
cholinergic, adrenergic
Esters of Choline and Alkaloids are…
Direct-Acting Cholinergic Agonists
What are the 2 types of choline esters? Describe their absorbtion/distribution.
- acetylcholine
- bethanechol
(not absorbed/distributed well)
What are the 3 types of alkaloids? Describe their absorbtion/distribution.
- muscarine
- nicotine
- pilocarpine
(absorbed/distributed well, even in the CNS)
M3 receptors are found where in the body?
- eye
- glands (salivary, sweat, etc.)
- bladder
- genitals
- intestines/colon
- stomach
- bronchi
- endothelial cells
M2 receptors are found where in the body?
- heart
M5 receptors are found where in the body?
- endothelial cells
