MUSCARINIC AGONISTS (M-CHOLINOMIMETICS)

CHOLINOnegative DRUGS)

ANTICHOLINESTERASES

List of drugs

Reversible anticholinesterases: Neostigmine bromide, Pyridostigmine bromide

Irreversible anticholinesterases: Arminum, Echothiophate

Mechanism of action

These drugs produce inhibition of acetylcholinesterase that results in accumulation of acetylcholine in the synaptic cleft.

Neostigmine and pyridostigmine produce reversible inhibition of acetylcholinesterase, arminum and echothiophate produce irreversible inhibition of acetylcholinesterase

Pharmacological effects

These drugs produce inhibition of acetylcholinesterase that results in accumulation of acetylcholine in the synaptic cleft. In this situation acetylcholine more stronger activates M- and N-cholinergic receptors and, therefore, induces aforementioned effects:

Type of receptors	Organ	Effect
Stimulation of M-cholinoreceptors	Eye	Constriction of pupil (miosis)
Salivary glands	Increasing of saliva secretion
Heart	Decreasing of heart rate, heart contractility, heart conductance and heart excitability
Bronchi	Constriction (due to contraction of smooth muscles of bronchi)
Gastro-intestinal tract (GIT) organs: stomach, small intestine, gall bladder etc.	Increasing of motility (due to contraction of smooth muscles of GIT organs)
Urinary bladder	Constriction (due to contraction of smooth muscles of urinary bladder)
Stimulation of N-cholinoreceptors	Skeletal muscles	Increasing of contractility
Autonomic ganglions	Constriction of blood vessels Increasing of uterus contractility

Indications

1. Glaucoma (increasing of intraocular pressure)

Neostigmine, Pyridostigmine, Arminum, Echothiophate → constriction of pupil → decreasing of intraocular pressure → treating of glaucoma. This effect depends on M-cholinoreceptors.

2. Atony of GIT organs and urinary bladder

Neostigmine, Pyridostigmine → increasing of motility of GIT organs and urinary bladder → treating of atony. This effect depends on M-cholinoreceptors.

3. Poor uterine contraction strength

Neostigmine, Pyridostigmine → increasing of uterus contractility → inducing of labor (delivery).

This effect depends on N-cholinoreceptors.

4. Myasthenia gravis (weakness of skeletal muscles)

Neostigmine, Pyridostigmine → increasing of contractility of skeletal muscles → treating of myasthenia gravis This effect depends on N-cholinoreceptors.

MUSCARINIC AGONISTS (M-CHOLINOMIMETICS)

List of drugs

Pilocarpine hydrochloride

Mechanism of action

Direct stimulation of M-cholinoreceptors. Don’t stimulate N-cholinoreceptors!

Pharmacological effects

Type of receptors	Organ	Effect
Stimulation of M-cholinoreceptors	Eye	Constriction of pupil (miosis)
Salivary glands	Increasing of saliva secretion
Heart	Decreasing of heart rate, heart contractility, heart conductance and heart excitability
Bronchi	Constriction (due to contraction of smooth muscles of bronchi)
Gastro-intestinal tract (GIT) organs: stomach, small intestine, gall bladder etc.	Increasing of motility (due to contraction of smooth muscles of GIT organs)
Urinary bladder	Constriction (due to contraction of smooth muscles of urinary bladder)

Indications

1. Glaucoma (increasing of intraocular pressure)

Pilocarpine → constriction of pupil → decreasing of intraocular pressure → treating of glaucoma.

Date: 2015-12-18; view: 1131

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