Psychiatric Drugs and Medications Q 15
Cholinergic agents are used to:
A. Produce miosis
B. Facilitate neuromuscular blockade
C. Synergize neuromuscular blockers
D. Facilitate tricyclic activity
Correct Answer: A. Produce miosis.
Miosis is a parasympathetic activity and is, therefore, the correct choice. Cholinergic medications are a category of pharmaceutical agents that act upon the neurotransmitter acetylcholine, the primary neurotransmitter within the parasympathetic nervous system (PNS). There are two broad categories of cholinergic drugs: direct-acting and indirect-acting. The direct-acting cholinergic agonists work by directly binding to and activating the muscarinic receptors. Indirect-acting cholinergic agents increase the availability of acetylcholine at the cholinergic receptors. B, C and D are incorrect because cholinergic agents are antidotes to neuromuscular blockers and tricyclic antidepressants.
Option B: Acetylcholine is a major neurotransmitter in the body. Depending on the type of receptors through which it undergoes mediation, the peripheral actions of acetylcholine classify as working on muscarinic (M1, M2, M3, M4, M5) or nicotinic (Nm, Nn) receptors. M1 receptors are present on the gastric parietal cells and in the central nervous system. M2 receptors are present on the heart, visceral smooth muscle. M3 receptors on the smooth muscle, exocrine glands, and receptors of the bladder. Nicotinic receptors are present in the central nervous system, adrenal medulla, autonomic ganglia, and neuromuscular junction.
Option C: The peripheral nervous system consists of the autonomic and the somatic nervous system. The autonomic nervous system can be further broken down into sympathetic and parasympathetic nervous systems. The parasympathetic nervous system regulates various organ and gland functions and primarily uses acetylcholine as its primary neurotransmitter, as do all the cholinomimetics.
Option D: Anticholinesterase medications are agents that inhibit choline esterase, protect acetylcholine from hydrolysis, and produce cholinergic effects. Anticholinesterases further classify into reversible (carbamates) and irreversible agents (organophosphates).