3 4 cholinergic pharmacology younus h johan 2016
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3 4 cholinergic pharmacology younus h johan 2016
- 1. Important drugs used in glaucoma Dr. Younus H JohanDr. Younus H Johan Department of pharmacology & toxicology College of pharmacy University of al-anbar 2016
- 6. Normal
- 15. Drugs or class Nature of action and important remarks Cholinergic agents Muscarinic agonists (pilocarpine) Anticholinesterase s [physostigmine, Improved drainage of aqueous humour (contracting the longitudinal muscle of the ciliary body leading to opening the trabecular meshwork around Schlemm’s canal (drainage channels), immediate drops [physostigmine, DFP (isoflurophate)] channels), immediate drop (IOP). •acute glaucoma •chronic open-angle glaucoma. M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 17. Drugs or class Nature of action and important remarks -blockers Timolol Betaxolol Cartelol Metipranolol Decrease production of AH -to reduced IOP. No effect on focusing for near vision or pupil size; (used inMetipranolol (used in chronic open-angle glaucoma, narrow and acute glaucoma. M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 18. Drugs or class Nature of action and important remarks α-agonists Non-selective Adrenaline α2-selective Praclonidine Enhances AH outflow (drainage, -receptors) by increasing PG production that enhance uveoscleral drainage decreases production of AH by vasoconstriction of the ciliary body bloodPraclonidine Brimonidine vasoconstriction of the ciliary body blood vessels leading to reduced IOP. Topical 2% adrenaline solution used in chronic open-angle glaucoma. C/I •closed-angle •acute glaucomas M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 19. Drugs or class Nature of action and important remarks Prostaglandins (PGF2α derivatives: latanoprost, unoprostone) Increase outflow by acting at the FP receptor -stimulates collagenase and metalloproteinase to degrade the extracellular matrix between ciliary muscle bundles, which in turn leads to the reduction of hydraulic resistance to uveoscleral flow SESE •irreversible brown pigmentation of the iris and eyelashes, •Eyelash : lengthening, thickening •drying of the eyes, and conjunctivitis. M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 20. Drugs or class Nature of action and important remarks Diuretics Carbonic anhydrase inhibitors Acetazolamide Decreases production of AH by blocking carbonic anhydrase in the ciliary body leading to reduced IOP. •chronic glaucoma •acute closed-angle glaucoma.•acute closed-angle glaucoma. Osmotic agents Mannitol Reduces IOP in acute closed-angle glaucoma. M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 21. Summary of selected mydriatic and cycloplegicsmydriatic and cycloplegics
- 23. Drug Duration Use Tropicamide 3-6 hr Fundus examination Homatropine 1-3 days Cycloplegic for refraction* in children Atropine 7-10 days For refraction as above; also iridocyclitis** (+ phenylephrine) They may precipitate acute glaucoma in the elderly and predisposed patients M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 25. Anticholinergic drugs Dr. Younus H Johan Department of pharmacology & toxicology College of pharmacy University of al-anbar
- 28. Effects • Decreased secretion • Mydriasis • Cycloplegia (decreased accommodation ) • Hyperthermia • Tachycardia Antichloinergic prototype: Atropine • Sedation • Urinary retention and constipation • Behavioural excitation and hallucinations
- 29. Selected therapeutic uses and important remarks* Antimuscarinic agents • to produce mydriasis & cycloplegia prior to refraction (7 days) • spastic disorders of GI and lower urinary tracts • organophosphate poisoning Atropine ( click ) • organophosphate poisoning • premedication prior to surgery, to suppress respiratory secretion in children M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 30. Selected therapeutic uses and important remarks* Antimuscarinic agents • to produce mydriasis & cycloplegia prior to refraction (7 days) • spastic disorders of GI and lower urinary tracts • organophosphate poisoning • premedication prior to surgery, to suppress respiratory secretion in children Atropine ( click ) • Cycloplegic for refraction in children (24 hr)Homatropine • Fundus examination (3 hr)Tropicamide M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 31. Selected therapeutic uses and important remarks* Antimuscarinic agents • In obstetrics with morphine to produce amnesia and sedation Scopolamine (hyoscine) and sedation • Motion sickness (hyoscine) • Asthma (inhalation)Ipratropium M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 32. Selected therapeutic uses and important remarks* Antimuscarinic agents • With chlordiazepoxide (Librax®) in GI disorders like • peptic ulcer, • nervous dyspepsia, • irritable bowel syndrome, • spastic colitis, • mild ulcerative colitis Clidinium With trifluoperazine (Stelabid®) in • peptic ulcer, • visceral spasm Isopropamide • Peptic ulcer (inhibits acid secretion),Pirenzepine • Peptic ulcer (inhibits acid secretion), • poorly enters the CNS, thus, no or little CNS side-effects Pirenzepine • Peptic ulcer, • irritable bowel syndrome, & • urinary disorders of storage (urinary frequency, incontinence, nocturnal enuresis Propantheline • Urinary disorders of storage (as above)Emepronium (Cetiprin®) M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 33. Selected therapeutic uses and important remarks* Antimuscarinic agents • Peptic ulcer (inhibits acid secretion), • poorly enters the CNS, thus, no or little CNS side-effects Pirenzepine • Peptic ulcer, • irritable bowel syndrome, & Propantheline • irritable bowel syndrome, & • urinary disorders of storage (urinary frequency, incontinence, nocturnal enuresis • Urinary disorders of storage (as above)Emepronium (Cetiprin®) M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 34. CNS Agents Benzotropine (Centrally acting antimuscarinic antagonists) • Drug induced dystonias • Parkinson’s disease Benzotropine Procyclidine Benzhexol-HCl Orphenadrine Adverse-effects commonly observed with cholinergic antagonists: blurred vision, mydriasis, tachycardia, constipation, urinary retention, and confusion. M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 35. Moderately severe to severe hypertension Ganglionic blockers MecamylamineMecamylamine Short-term treatment of hypertension (emergency lowering of blood pressure, when other agents cannot be used) Trimethaphan M.AK.Lafi : Essentials of Medical Pharmacology 2009
- 36. See appropriate section in the chapter on CNS pharmacology (later on) Neuromuscular blockers Nondepolarising (competitive agents)(competitive agents) Depolarising agents M.AK.Lafi : Essentials of Medical Pharmacology 2009