Cholinesterase Inhibitors Overview

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Questions and Answers

The function of _____ is the breakdown of acetylcholine at the synapse.

acetylcholinesterase

What are drugs that prevent degradation of acetylcholine by acetylcholinesterase called?

Cholinesterase inhibitors

What is a key feature of cholinesterase inhibitors?

Not selective; acts at all cholinergic receptors.

What is the prototype drug for reversible cholinesterase inhibitors?

Neostigmine (Prostigmin) Signup and view all the answers

What medication class does Neostigmine (Prostigmin) belong to?

Reversible cholinesterase inhibitor Signup and view all the answers

What is the mechanism of action for Cholinesterase inhibitors?

Inhibits acetylcholinesterase, decreasing breakdown of acetylcholine. Signup and view all the answers

What are the pharmacologic effects of Neostigmine?

Intensifies transmission of ACh at junctions. Signup and view all the answers

What are the therapeutic effects of cholinesterase inhibitors at therapeutic doses?

Increased cholinergic neurotransmission. Signup and view all the answers

What are some muscarinic responses expected from cholinesterase inhibitors?

Increased glandular secretions, bradycardia, urinary urgency. Signup and view all the answers

What are the neuromuscular effects of Neostigmine?

Dose-dependent effects, increasing force of contraction. Signup and view all the answers

What happens to the CNS effects with increasing concentration of neostigmine?

Mild stimulation at therapeutic doses, depression at toxic levels. Signup and view all the answers

What therapeutic use does Neostigmine have for myasthenia gravis?

Increases acetylcholine concentration to improve muscle strength. Signup and view all the answers

How does Neostigmine reverse nondepolarizing neuromuscular blocking agents?

Increases concentration of acetylcholine at the synapse. Signup and view all the answers

What are some adverse effects of Neostigmine related to muscarinic stimulation?

Excessive salivation, bradycardia, sweating. Signup and view all the answers

What can toxic doses of Neostigmine cause regarding neuromuscular blockade?

Reduced muscle contraction due to ACh accumulation. Signup and view all the answers

What are precautions, warnings, and contraindications for Cholinesterase inhibitors?

Same as for direct acting muscarinic agonists. Signup and view all the answers

Study Notes

Cholinesterase Inhibitors Overview

Function of acetylcholinesterase: Breakdown of acetylcholine at synapses.
Cholinesterase inhibitors prevent degradation of acetylcholine, acting as indirect-acting agonists by increasing acetylcholine availability.

Key Features of Cholinesterase Inhibitors

Not selective: Affect all cholinergic receptors (muscarinic and nicotinic).
Varied duration: Some are reversible while others are irreversible. Irreversible inhibitors bond strongly to enzymes, preventing their activity.

Prototype Drug

Neostigmine (Prostigmin) is the prototype reversible cholinesterase inhibitor.

Mechanism of Action

Inhibits acetylcholinesterase, leading to decreased acetylcholine breakdown and increased neurotransmitter availability.

Pharmacologic Effects

Intensifies ACh transmission at synapses where ACh is the transmitter.
Effects primarily observed at synaptic junctions and neuromuscular junction, with minimal impact on ganglionic nicotinic receptors or CNS receptors unless high doses are used.
Muscarinic responses mimic those of direct-acting agonists, leading to effects like increased glandular secretions and GI motility, bradycardia, urinary urgency, and bronchial constriction.
Neuromuscular effects are dose-dependent; therapeutic doses increase muscle contraction while toxic doses can reduce it due to continuous depolarization.
Central nervous system effects vary with concentration; therapeutic levels may stimulate while toxic levels may depress CNS activity.

Therapeutic Uses of Neostigmine

Treatment of Myasthenia Gravis: Increases acetylcholine at nicotinic-M receptors, improving muscle strength and reducing fatigue.
Reversal of nondepolarizing neuromuscular blockers (e.g., vecuronium) during surgical procedures by increasing synaptic acetylcholine concentration.

Adverse Effects

Excessive muscarinic stimulation can lead to symptoms like salivation, increased gastric secretions, GI motility, urinary urgency, bradycardia, sweating, pupil constriction (miosis), and accommodation spasm.
Toxic doses can cause neuromuscular blockade, reducing muscle contraction due to acetylcholine accumulation.

Precautions, Warnings, and Contraindications

Follow similar guidelines as for direct-acting muscarinic agonists; consult clinical references for specifics.

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Description

This quiz covers the essential concepts of cholinesterase inhibitors, focusing on their function, mechanism of action, and pharmacologic effects. You'll learn about the prototype drug neostigmine and how these inhibitors affect acetylcholine levels at synapses. Test your understanding of the different types and characteristics of these drugs.