Pharmacology

1. Pharmacology Unit II

2. Autonomic Nervous System • Parasympathetic nervous system • Sympathetic nervous sytem

3. Sympathetic and Parasympathetic Some organs – may have opposing effects Male sex organs – may have complementary effects Other organs – only regulated by one – blood vessels

4. 3 transmitters • Acetylcholine • Norepinephrine • epinephrine

5. Cholinergic receptors • Nicotinic N • Nicotinic M • muscarinic

6. Adrenergic receptors • Alpha 1 • Alpha 2 • Beta 1 • Beta 2 • Dopamine

7. Cholinergic Drugs • Agents that influence the activity of cholinergic receptors • Mimic or block actions of acetylcholine

8. Six categories • Muscarinic agonists – mimic • Muscarinic antagonists – block • Ganglionic stimulating – mimic effects • Ganglionic blocking – block • Neuromuscular blocking – block acetylcholine • Cholinesterase inhibitors – prevent breakdown acetylcholine

9. Muscarinic Agonists • Bind to muscarinic receptors – activation • Bethanechol • Bradycardia • Increased secretion – sweating, bronchial, GI • Smooth muscle contraction • Pupillary constriction and accommodation for near vision(contraction of ciliary muscle)

10. Principle indication – urinary retention • Should be given only orally or subcutaneously – side effects increase with sc route • Contraindicated in patients with gastric ulcers

11. Pilocarpine • Given for glaucoma

12. Poisoning • Mushrooms and medications • Excessive salivation, bronchospasm, bradycardia, hypotension • Atropine – muscarinic blocking agent – drug of choice to reverse signs of toxicity

13. Muscarinic Antagonists • Atropine – also called anticholinergic • Blocks the action of acetylcholine at muscarinic receptors

14. Atropine • Increases heart rate • Decreases secretion • Relaxation of smooth muscle – bronchi, urinary bladder, GI tract • Dilation of pupil • Relaxes ciliary muscle – focus far vision

15. Atropine • 3 – hour half-life • Orally, topically, injection • Used to be used preoperatively – to decrease tracheal secretions

16. Adverse effects • Dry mouth, constipation, blurred vision, increased intraocular pressure, urinary retention, tachycardia, asthma – drying of secretions

17. Scopolamine • Produces sedation • Suppresses emesis and motion sickness

18. Dicyclomine • Bentyl, Di-Spaz • Used for irritable bowel

19. Poisoning • Antimuscarinic poisoning • From belladonna, atropine, scopolamine, some antihistamines • Dry mouth, blurred vision, hyperthermia, hallucinations, respiratory depression

20. antidote • Physostigmine – an inhibitor of acetylcholinesterase • Charcoal, syrup of ipecac

21. Cholinesterase inhibitors • Reversible – neostigmine • Indication – myasthenia gravis – autoimmune disorder nicotinic M receptors are reduced at neuromuscular junction

22. Reverse nondepolarizing neuromuscular blockade • PACU

23. Cholinergic crisis • Overdose with cholinesterase inhibitors • Increased bronchial secretions • Respiratory failure • Atropine may be helpful

24. Irreversible • Cholinesterase inhibitors – found in insecticides • Nerve gases • Indication - glaucoma

25. Neuromuscular blockers

26. Adrenergic Agonists • Sympathomimetics • Activate adrenergic receptors – catecholamines vs. noncatecholamines

27. Catecholamines • Norepinephrine • Epinephrine • Isoproterenol • Dopamine • Dobutamine

28. Noncatecholamines • Ephedrine • Phenylephrine • Terbutaline

29. Catacholamine receptor sites located throughout the body

30. Alpha receptor sites • Alpha-adrenergic receptor sites smooth muscle of blood vessels, GI tract, GU tract – when stimulated – produce vasoconstriction

31. Beta 1 • Heart muscle • Increase contractility - +inotrope • Increase heart rate - +chronotrope • Increase av and sa node conduction - +dromotrope

32. Beta 2 • Respiratory system – located in bronchial smooth muscle • Produce bronchial dilation • Bronchodilator • Would increase blood sugar in pts with diabetes

33. Adrenergic antagonists • Alpha blockade – for essential hypertension • Cause vasodilation • Pheochromocytoma, reversal of toxicity from epinephrine, raynaud’s disease

34. Prazosin – selective blockade – minipress • Terazosin – hytrin • Doxazosin - cardura

35. Phentolamine – regitine – nonselective – pheochromocytoma - infiltration

36. Beta blockade • Angina • Hypertension • Cardiac dysrhythmias • MI • Heart failure • hyperthyroidism

37. Adverse effects • Brady • Decreased CO • AV block • Rebound cardiac excitation

38. Adverse effects of beta2 blockade • Bronchconstriction - asthma • Inhibition of glycogenolysis • Propranolol - Inderal

39. Metoprolol • Cardioselective – only blocks beta 1 receptors • At usual therapeutic doses

40. Indirect-acting antiadrenergic agents • Reduce stimulation of peripheral adrenergic receptors

41. Reserpine – hypertension • Clonidine – centrally acting (Catapres)

42. GI tract • Alpha1 and beta2 receptor sites • Increasing gastric motility • Primarily anorexiants • Dexadrine • Methamphetamine (Desoxyn)

43. Also helpful for reducing intraocular pressure and dilating pupils • Good for glaucoma

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