1. Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. CHAPTER 20 Cholinergic Drugs

2. 2 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Cholinergic Drugs  Drugs that stimulate the parasympathetic nervous system (PSNS)  The PSNS is the opposing system to the SNS

3. 3 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Cholinergic Drugs (cont’d)  Also known as cholinergic agonists or parasympathomimetics parasympathomimetics  Mimic effects of the PSNS neurotransmitter acetylcholine (ACh) acetylcholine (ACh)

4. 4 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

5. 5 Cholinergic Receptors  Two types, determined by:  Location  Action once stimulated  Nicotinic receptors  Muscarinic receptors

6. 6 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nicotinic Receptors  Located in the ganglia of both the PSNS and SNS  Named nicotinic because they can be stimulated by the alkaloid nicotine

7. 7 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Muscarinic Receptors  Located postsynaptically in the effector organs of the PSNS  Smooth muscle  Cardiac muscle  Glands  Named muscarinic because they can be stimulated by the alkaloid muscarine

8. 8 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

9. 9 Mechanism of Action  Direct-acting cholinergic agonists  Bind to cholinergic receptors, activating them  Indirect-acting cholinergic agonists  Inhibit the enzyme acetylcholinesterase, which breaks down ACh  Results in more ACh available at the receptors

10. 10 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Indirect-Acting (Cholinesterase Inhibitors)  Reversible  Bind to cholinesterase for a period of minutes to hours  Irreversible  Bind to cholinesterase and form a permanent covalent bond  The body must make new cholinesterase to break these bonds

11. 11 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Effects  Effects seen when PSNS is stimulated  The PSNS is the “rest and digest” system

12. 12 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Effects (cont’d)  SLUDGE acronym  Salivation  Lacrimation  Urinary incontinence  Diarrhea  Gastrointestinal cramps  Emesis

13. 13 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Effects (cont’d)  Stimulate intestine and bladder  Increased gastric secretions  Increased gastrointestinal motility  Increased urinary frequency  Stimulate pupils  Constriction (miosis)  Reduced intraocular pressure  Increased salivation and sweating

14. 14 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Effects (cont’d)  Cardiovascular effects  Decreased heart rate  Vasodilation  Respiratory effects  Bronchial constriction, narrowed airways

15. 15 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Effects (cont’d)  At recommended doses, cholinergics primarily affect muscarinic receptors  At high doses, cholinergics stimulate nicotinic receptors

16. 16 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Effects (cont’d)  Desired effects are from muscarinic receptor stimulation  Many undesirable effects are caused by stimulation of nicotinic receptors

17. 17 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Indications  Direct-acting drugs  Reduce intraocular pressure  Useful for glaucoma and intraocular surgery Acetylcholine Acetylcholine Carbachol Carbachol Pilocarpine Pilocarpine  Topical application because of poor oral absorption

18. 18 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Indications (cont’d)  Direct-acting drug—bethanechol  Increases tone and motility of bladder and GI tract  Relaxes sphincters in bladder and GI tract, allowing them to empty  Helpful for postsurgical atony of the bladder and GI tract  Oral dose or SC injection

19. 19 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Indications (cont’d)  Indirect-acting drugs  Cause skeletal muscle contractions  Used for diagnosis and treatment of myasthenia gravis  Used to reverse neuromuscular blocking drugs  Used to reverse anticholinergic poisoning (antidote) Examples: physostigmine, pyridostigmine Examples: physostigmine, pyridostigmine

20. 20 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Indications (cont’d)  Indirect-acting drug—cevimeline (Evoxac)  Used to treat xerostomia (dry mouth) resulting from Sjögren’s syndrome

21. 21 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Indications (cont’d)  Indirect-acting anticholinesterase drugs  Used for treatment of mild to moderate Alzheimer’s disease donepezil (Aricept) donepezil (Aricept) tacrine (Cognex) tacrine (Cognex) galantamine (Razadyne) galantamine (Razadyne) rivastigmine (Exelon) rivastigmine (Exelon)

22. 22 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Indications (cont’d)  memantine (Namenda)  Not a cholinergic drug  Also used in the treatment of Alzheimer’s disease

23. 23 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Adverse Effects  Adverse effects are a result of overstimulation of the PSNS  Cardiovascular  Bradycardia, hypotension, conduction abnormalities (AV block and cardiac arrest)  CNS  Headache, dizziness, convulsions  Gastrointestinal  Abdominal cramps, increased secretions, nausea, vomiting

24. 24 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Adverse Effects (cont’d)  Respiratory  Increased bronchial secretions, bronchospasms  Other  Lacrimation, sweating, salivation, loss of binocular accommodation, miosis

25. 25 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Interactions  Anticholinergics, antihistamines, sympathomimetics  Antagonize cholinergic drugs, resulting in decreased responses  Other cholinergic drugs  Additive effects

26. 26 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Herbal Products: Gingko  Common uses  Organic brain syndrome  Vertigo  Tinnitus  May cause GI upset, headache, bleeding  Potential interactions  Aspirin  NSAIDs  Anticoagulants  Anticonvulsants  Others

27. 27 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications  Note that these drugs will stimulate the PSNS and mimic the action of ACh  Assess for allergies, presence of GI or GU obstructions, asthma, peptic ulcer disease, or coronary artery disease  Perform baseline assessment of vital signs and systems overview

28. 28 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d)  Medications should be taken as ordered and not abruptly stopped  Doses should be spread evenly apart to optimize the effects of the medication  Overdosing can cause life-threatening problems. Patients should not adjust dosages unless directed by their physician

29. 29 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d)  Encourage patients with myasthenia gravis to take medication 30 minutes before eating to help improve chewing and swallowing  When cholinergic drugs are prescribed for Alzheimer’s disease, be honest with caregivers and patients that the drugs are for management of symptoms (not a cure)  Therapeutic effects of anti-Alzheimer’s drugs may not occur for up to 6 weeks

30. 30 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d)  Atropine is the antidote for cholinergics, and it should be available in the patient’s room for immediate use if needed  Patients should notify their physician if they experience muscle weakness, abdominal cramps, diarrhea, or difficulty breathing

31. 31 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d)  Monitor for therapeutic effects  Alleviated signs and symptoms of myasthenia gravis  In postoperative patients with decreased GI peristalsis, monitor for: Increased bowel sounds Increased bowel sounds Passage of flatus Passage of flatus Occurrence of bowel movements Occurrence of bowel movements

32. 32 Mosby items and derived items © 2011, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d)  Monitor for therapeutic effects  In patients with urinary retention/hypotonic bladder, urination should occur within 60 minutes of bethanechol administration  Also monitor for adverse effects