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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: 1409
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