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Cholinoceptor blocking drugs

. Cholinoceptor blocking drugs (cholinoceptor antagonists) are divided into:Muscarinic receptor blockers: block muscarinic receptors Nicotinic receptor blockers: block nicotinic receptors and include: a) Ganglion blocking drugs b) Neuromuscular junction bl

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Cholinoceptor blocking drugs

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    1. Cholinoceptor blocking drugs

    2. Cholinoceptor blocking drugs (cholinoceptor antagonists) are divided into: Muscarinic receptor blockers: block muscarinic receptors Nicotinic receptor blockers: block nicotinic receptors and include: a) Ganglion blocking drugs b) Neuromuscular junction blockers

    3. Muscarinic receptor blockers (antimuscarinic or parasympatholytic because they block the effects of parasympathetic autonomic discharge) I- Natural: 1- Atropine 2- Scopolamine (hyoscine) II- Synthetic Substitutes a) Tertiary amines : Propantheline Pirenzepine Dicyclomine Tropicamide Benztropine Oxybutynin b) Quaternary amines 1. Ipratropium 2. Trospium

    4. Properties of muscarinic receptor blockers

    5. Action of acetylcholine at cholinergic receptors 9

    6. Effect of muscarinic receptor blockers on CNS

    7. Organ system effects of atropine

    8. Adverse effects of atropine 1- Mydraisia and cycloplegia 2- Tachycardia (but usually no effect on blood pressure) 2- Vasodilatation of skin blood vessels with toxic doses (leading to flushing) 3- Decreased motility of GIT and urinary bladder (causing retention of urine) 4- Decreased secretion of glands (dry eye, dry mouth, decreased bronchial secretion).

    9. Adverse effects of atropine Depend on therapeutic use Treatment is usually directed at one organ. Other organ effects are considered as side effects. Therefore mydriasis and cycloplegia are side effects of the use of atropine to treat increased intestinal motility but are therapeutic uses in opthalmology

    10. Contraindications of atropine 1- Patients with angle closure glaucoma 2- Patients with shallow anterior chamber 3- Senile hyperplasia of the prostate 4- Patients with gastric ulcer (increase symptoms due to slowing gastric emptying)

    11. Therapeutic uses of atropine 1- Preanesthetic mediction: Given half an hour before general anesthesia to: Decrease salivary and bronchial secretion Protect the heart from excessive vagal tone which may occur during anesthesia Counteract the depressant effect of morphine on the respiratory center 2- Antispasmodic 3- Treatment of severe bradycardia 4- Antidote to parasympathomimetics 5- Hyperhidrosis 6- Treatment of poisoning with cholinoceptor stimulants (as cholinesterase inhibitors)

    12. Scopolamine (hyoscine) Similar to atropine but has more CNS depressant actions Effect on other organs, adverse effects , contraindications and uses are similar to atropine. It is preferred than atropine in preanesthetic medication because of its CNS depressant action (causing sedation and amnesia) In addition, it is used to treat vertigo and motion sickness

    13. Synthetic atropine substitutes Divided into 4 groups according to clinical uses: 1- Mydriatic atropine substitutes 2- Bronchodilator atropine substitutes

    14. Mydriatic atropine substitutes

    15. Uses for atropine substitutes 1- Mydriasis Indications for mydriasis are either: Short period mydriasis as in opthalmological examination: Short acting mydriatics as alpha adrenoreceptor stimulants are preferred Long period mydriasis as in prevention of adhesion in uveitis and iritis Mydriasis and cycloplegia as in opthalmological examination for the errors of refraction Atropine substitutes are used topically as eye drops or ointment in 2 and 3. The shorter acting drugs are preferred Adverse effects: prolonged mydriasis and cycloplegia leading to blurred vision and precipitation of glaucoma in patients with narrow anterior chamber

    16. 2- Bronchodilatation: Ipratropium and tiotropium Indications: 1- Bronchial asthma 2- Chronic obstructive pulmonary disease (COPD) Administration: by inhalation as aerosol (to provide maximal concentration at the site of action) Effect: bronchodilatation and reduction of bronchial secretion Adverse effects : minimal (not absorbed) Tiotropium is long acting and is given once daily

    17. 3- Urinary disorders 1-Urolithiasis to relieve smooth muscle spasm 2- Symptomatic treatment of urgency associated with inflammation of the bladder (in combination with the specific antimicrobial) 3- Bladder spasm after urologic surgery 4- Reduction of involuntary voiding in patients with neurologic diseases

    18. Drugs used for urinary disorders: 1- Selective M3 blocker a) Oxybutynin b) Darifenacin c) Solifenacin d) Tolterodine 2- Unselective M3 blocker Trospium

    19. 4- Treatment of parkinsonism

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