DOC-20240823-WA0011..pdf

Parasympathomime tic and parasympatholytic drugs Section 3 1-Neostigmine Trad names: Prostigmin , amostigmine -- Mechanism of action: It act indirectly by inhibition of cholinestrase enzyme and directly on nicotinic receptors in some tissues like neuromuscular junction --Therape...

Parasympathomime tic and parasympatholytic drugs Section 3 1-Neostigmine Trad names: Prostigmin , amostigmine -- Mechanism of action: It act indirectly by inhibition of cholinestrase enzyme and directly on nicotinic receptors in some tissues like neuromuscular junction --Therapeutics uses: Paralytic ileus and atony of urinary bladder. Myasthenia gravis -- Adverse effects 1. salivation, flushing 2. decreased blood pressure 3. nausea, abdominal pain, diarrhea, and bronchospasm. 4. Neostigmine does not cause CNS side effects and is not used to overcome toxicity of central-acting antimuscarinic agents such as atropine. -- Toxicity : Overdosage of Neostigmine can cause cholinergic crisis, which is characterized by increasing muscle weakness, and by involvement of the muscles of respiration, may result in death -- Contraindication Neostigmine is contraindicated when intestinal or urinary bladder obstruction is present. 2-Bethanechol -- Trad names: --Mechanism of action : directly stimulates muscarinic receptors, causing increased intestinal motility and tone. It also stimulates the detrusor muscle of the bladder, whereas the trigone and sphincter muscles are relaxed. These effects stimulate urination. -- Therapeutic uses In urologic treatment, particularly in postpartum or postoperative, nonobstructive urinary retention. Bethanechol may also be used to treat neurogenic atony as well as megacolon. -- Adverse effects sweating, salivation, flushing decreased blood pressure (with reflex tachycardia) nausea, abdominal pain, diarrhea, and bronchospasm. Atropine sulfate may be administered to overcome severe cardiovascular or bronchoconstrictor responses to this agent. --Contraindication Bethanechol is contraindicated when intestinal or urinary bladder obstruction is present 1-Atropine Atropine is a tertiary amine extracted from belladonna alkaloid. -- Mechanism of action It has a high affinity for muscarinic receptors and binds competitively to prevent ACh from binding. Atropine acts both centrally and peripherally. General actions last about 4 hours; however, effects of topical administration in the eye may persist for days. Therapeutic uses 1. Ophthalmic topical atropine permits the measurement of refractive errors without interference by the accommodative capacity of the eye. Shorter-acting antimuscarinics (cyclopentolate and tropicamide) have largely replaced atropine due to prolonged mydriasis observed with atropine (7 to 14 days vs. 6 to 24 hours with other agents). 2. Antispasmodic atropine is used as an antispasmodic agent to relax the GI tract. 3. Cardiovascular Injectable atropine used to treat bradycardia of varying etiologies. 4. Antisecretory atropine is sometimes used as an antisecretory agent to block secretions in the respiratory tract prior to surgery. 5. Antidote for cholinergic agonists atropine is used for the treatment of organophosphate (insecticides, nerve gases) poisoning, of overdose of clinically used anticholinesterases such as physostigmine, and in some types of mushroom poisoning (certain mushrooms contain cholinergic substances that block cholinesterases). ---Adverse effects Depending on the dose, atropine may cause: 1. dry mouth, blurred vision, “sandy eyes,” tachycardia, urinary retention, and constipation. 2. Effects on the CNS include restlessness, confusion, hallucinations, and delirium, which may progress to depression, collapse of the circulatory and respiratory systems, and death. 3. The drug may be dangerous in children, because they are sensitive to its effects, particularly to rapid increases in body temperature. --- Contraindication glaucoma pyloric stenosis thyrotoxicosis fever urinary tract obstruction and ileus. 2- Solifenacin -- Trad name Vesicare 5, 10, sofenacin 5,10 -- Mechanism of action synthetic atropine-like drugs with antimuscarinic actions selective M3 muscarinic receptor antagonists specially in the blader Indication Treatment of overactive bladder Enuresis urinary incontinence Neurogenic detrusor overactivity -- Adverse effects CNS effects ( confusion, dizziness, drowsiness, hallucinations) GI effects ( constipation, xerostomia) ophthalmic effects ( blurred vision) Angioedema in case of Hypersensitivity -- Contraindications Hypersensitivity, urinary retention uncontrolled narrow-angle glaucoma.