1. Drugs Affecting the Autonomic Nervous System
NRSG 305 – Pharmacology in Nursing
by Joanna Shedd, MS, RN

2. Autonomic Nervous System
Parasympathetic>preganglionic>postganglionic>release ach>binds to cholinergic nerves> Muscarinic
Sympathetic>preganglionic>post
ganglionic>release ach>
postganglionic>release NE>binds to
adrenergic>alpha and beta
Refer to cheat sheet on page 481

4. Peripheral Nervous System
Somatic nervous system – voluntary control over skeletal muscle
Autonomic nervous system – involuntary control over the contraction of smooth muscle, cardiac muscle, gland secretion

5. Receptors in the autonomic nervous system
Diagram needed

6. Autonomic Nervous System (ANS)
Sympathetic – “flight or fight”
Ready for immediate stress
Increase of body systems
Parasympathetic – “rest and digest”
Nonstressful conditions
Decrease body systems
Digestion increased

9. Synapse Communication between neurons, muscles and glands
Connection of neurons
Synapse – end point of one neuron junction (presynaptic), synaptic cleft, and start of new neuron (postsynaptic)

10. Drug Effects Affect synthesis of neurotransmitters
Prevent storage of neurotransmittters
Influence the release of neurotransmitters
Bind to the receptor site of postsynaptic neuron – increase autonomic function

11. ANS Neurotransmitters
Acetylcholine (Ach) – released by cholinergic nerves
Nicotinic receptors – Ach receptors in the preganglionic ganglia, effects similar to effects of nicotine (parasympathetic)
Muscarinic receptors – Ach receptors in postganglionic ending in target tissues, similar to effects of amanita muscaria
Fungus (northern hemisphere)
Deep red mushroom, orange, yellow
Cholinergic effects

12. ANS Transmitters Alpha receptors – alpha1 (vasoconstriction)
decrease GI motility, elevate BP,
mydriasis
alpha 2 (smooth muscle constriction) beta 1 (Positive chronotropic) increases HR (Positive inotropic) contractility
beta 2 (Bronchodilator) lungs

13. Neurotransmitter Disintegration
Ach
Destroyed by acetylcholinesterase
Norepinephrine (NE)
Reuptake of NE into nerve terminals for reuse
Inactivation by monoamine oxidase (MAO)

14. Baroreceptor Reflex (negative feedback)
The baroreceptor reflex regulates BP
The receptors are located in the carotid sinus and aortic arch
The brain sends impulses to the ANS
When there is a decrease in BP there is vasoconstriction and an increase in CO
When there is an increase in BP vasodilation and a decrease in BP

15. Autonomic Drug Classes
Sympathomimetics or adrenergic agonists – stimulate sympathetic system (SNS)
Parasympathomimetics or muscarinic agonists – stimulate parasympathetic system (PNS)
Parasympathetic = increase cholinergic responses, need to increase secretions

16. Autonomic Drug Classes
Adrenergic antagonists or adrenergic blockers – inhibit SNS
Anticholinergics or parasympatholytics or muscarinic blockers – inhibit PNS
Anticholinergics = parasympatholytics

17. Parasympathomimetics
AKA – cholinergic agents
Cholinergic = parasympathetic
Classic – acetylcholine
Does not stay long in body, rapidly destroyed after receptor binding
Direct acting – bind to cholinergic receptors to produce rest/digest response – AKA muscarinic agonist
Indirect acting – avoids destruction of Ach and allow to remain on cholinergic receptors for longer time – AKA cholinesterase inhibitors

18. Muscarinic Agonists or Parasympathomimetics
Muscarinic agonist = cholinergic agent
Causes receptor activation
The prototype is Bethanechol/ Urecholine
Reversibly binds to muscarinic cholingeric receptors
Relief of urinary retention postoperatively and post-partum

19. Adverse effects of Bethanechol
Hypotension
Bradycardia
Increased secretions
Exacerbation of asthma

20. Other Parasympathomimetic Drugs
Cevimeline/ Evoxac – tx of dry mouth
Pilocarpine/ Isopto Carpine – used for tx of glaucoma (decreases presssure)
Acetycholine – minimal therapeutic use – too rapid destruction

21. Nursing Management Parasympathetic Medications
Watch for adverse effects:
CI – Lithium:
increase CNS depression
taken together
CI – Adenosine :
increase chance heart block
Elderly – CNS stimulation:
Mistaken belief that symptoms may
be effects of old age or age‐related
illness

22. Parasympathomimetics
Cholinesterase Inhibitors (indirect acting)
Also known as anticholinesterases
Prevents the breakdown of Ach which leads to a subsequent increase of ACh at all junctions where ACh is effective
Classified as reversible and irreversible

23. Uses of Cholinesterase Inhibitors
Treatment of Myasthenia gravis (increase strength by increasing neuromuscular transmission)
Reverse the effects of neuromuscular blockade
Occurs naturally in venoms/poisons
Can be used as nerve gas

24. Myasthenia Gravis Ptosis Difficulty swallowing
Weakness of skeletal muscles
Anticholinesterases will increase Ach at the NMJ and increase muscle strength

25. Cholinesterase Inhibitors also called acetylcholinesterase Inhibitor
Increases acetylcholine
Increases glandular secretions
Bradycardia
Bronchial constriction
Increased motility of GI smooth muscle
Mild CNS stimulation with regular doses; depression of CNS with toxic levels
Take this medication at the same time every day

26. Precautions and Contraindications with Acetylcholinesterase inhibitors
Increases acetylcholine levels (sludge)
Not that it will cause, just be cautious with these patient:
Obstruction of GI tract
Obstruction of the urinary tract
Peptic ulcer disease
Asthma-bronchial constriction
Coronary insufficiency

27. Common Names Neostigmine/ Prostigmin Physostigmine/ Antilirium
Edrophonium/ Tensilon
Pyridostigmine/ Mestinon
Donepezil/ Aricept

28. Cholinergic and Myasthenic Crisis
Profuse secretions
Laryngospasm
Bronchoconstriction
Convulsions
Paralysis
Caused by overdose of medications or exacerbation of Myastenia Gravis

29. Cholinergic and Myasthenic Crisis
Extreme muscle weakness
Caused by worsening of disease
Edrophonium/ Tensilon challenge; if the symptoms are alleviated this is a Myasthenic crisis; if symptoms intensified cholinergic crisis
If increasing the meds decreases the s/s=Dz. was the problem. No change=meds are the problem

30. Treatment of Cholinergic or Myasthenic crisis
Cholinergic Crisis
Atropine - anticholinergic
Ventilatory support
Withhold the offending agent

31. Nursing Management of Cholinergic or Myasthenic crisis
CI – mechanical obstruction of GI and urinary
Build-up of Ach at junction sites
Profuse salivation
Increased muscle tone
Urinary frequency
Bronchoconstriction
Bradycardia
SLUDGE=salivation, lacrimation, urination, diaphoresis, GI, emesis

32. Uses of Neuromuscular Blocking Agents
Muscle relaxation/paralysis via inhibition of acetylcholine:
ACH cause constriction so blocking it=relaxation
Facilitation of mechanical ventilation
Facilitation of endotracheal intubation
Diagnosis of myasthenia gravis

33. Muscarinic Antagonists/ Parasympatholytic Drugs/ Antimuscarinic Drugs/ Muscarinic Blockers Blocks ACH, opposite of sludge
AKA Anticholinergic/ cholinergic blockers
Competitively blocks the actions of Ach
The prototype is Atropine (blocks muscarinic)
Given for the treatment of– pre-anesthetic use to decrease secretions, disorders of the eye, bradycardia, intestinal hypermotility, muscarinic agonist poisoning .

35. Adverse effects of Atropine
Xerostomia (dry mouth)
Blurred vision
Increase IOP (blocks ach=increased pressure)
Urinary retention
Constipation
Tachycardia
Anhidrosis – abnormal deficiency of sweat
Anhidrosis, an abnormal deficiency of sweat, can be classified as generalized (complete) or localized (partial). Generalized anhidrosis can lead to life-threatening impairment of thermoregulation. Localized anhidrosis rarely interferes with thermoregulation because it affects only a small percentage of the body’s eccrine (sweat) glands.

36. Other Anticholinergics
Oxybutynin/ Ditropan and Detrol – tx urinary incontinence=blocks ach to decrease urination
*Glycopyrrolate/ Robinul – “dry” field pre-anesthesia (respiratory secretions diminished)
Scopolamine – motion sickness
Ipratroprium bromide – tx
of asthma (blocks ach=
bronchodilation)

37. Atropine (Anti-Cholinergic) uses
Atropine given to treat:(blocks parasympathetic)
Muscarinic poisoning
Caused by direct-acting muscarinic agonists and anticholinesterases
(SLUDGE) Symptoms are produced by excessive activation of muscarinic receptors
Supportive therapy
Atropine is the drug of choice for bradycardia and cholinergic crisi

38. Anti-muscarinic Poisoning-Blocks ACH Too much atropine
Atropine is an anti-muscarinic/Anti-cholinergic
Overdose of Anti-muscarinic:
Caused by some anti-muscarinic drugs
Symptoms are due to blockade of muscarinic receptors

39. Treatment of Anti-muscarinic Poisoning
Minimize absorption of antimuscarinic agent- ipecac and activated charcoal
Give antidote-
Physostigmine acts by interfering with the metabolism of acetylcholine. Given to treat atropine over dose
or any other anti-cholinergic crisis

40. Some Important Terms
Muscarinic crisis-Abdominal pain, diarrhea, nausea, vomiting, lacrimation, blurred vision, bronchial hypersecretion due to parasympathetic hyperresponse
Cholinergic Crisis-An over-stimulation at a neuromuscular junction due to an excess of acetylcholine (ACh), as of a result of the inactivity (perhaps even inhibition) of acetylcholinesterase, caused by nerve gas, in patients with myasthenia gravis who have overdosed on cholinergic agents, or in surgical candidates, due to an excess of cholinesterase inhibitor given to reverse surgical muscle paralysis
Myastenia gravis- is treated with cholinergic drugs in attempt to decrease muscle weakness. Cholinergic drugs increase aceytcholine which stimulates muscles and decreases muscle weakness. Overdose of this drug, or adverse effects of this drug would result in a cholinergic crisis
Myasthenic crisis-An acute ↑ in requirement for anticholinesterase therapy or refractoriness to same, diagnosed by a Tensilon test, with transient ↓ of symptoms
Nicotinic crisis-Muscle weakness, fasciculations, cramping and dysphagia, due to over depolarization at the neuromuscular junction.

41. Mustard Gas Poisoning

42. Indications of Adrenergic Agonists or Sympathomimetics
Stimulates alpha 1
Give for treatment of:
Hemostasis
Nasal decongestant
Decreased BP
Miosis

43. Indications of Adrenergic Agonists or Sympathomimetics
Alpha 2
No clinical significance in the periphery
Centrally there is decrease sympathetic outflow
Smooth muscle constriction

44. Adverse effects of Alpha 1
Hypertension due to vasoconstriction
Necrosis of tissues because of lack of blood flow due to vasoconstriction
Tachycardia

45. Indications of Adrenergic Agonists
Beta 1
Cardiac arrest
Heart failure
Shock
Atrioventricular block

46. Indications of Adrenergic Agonists
Beta 2
Asthma (bronchodilates)
Delay of pre-term labor (relaxes uterine muscles)

47. Adrenergic Agonists Adverse Effects
Beta 1
Tachycardia
Angina pectoris

48. Adrenergic Agonists Adverse Effects
Beta 2 agonist
Hyperglycemia
Tremor

49. Indications for Epinephrine Usage
Treatment of choice for anaphylaxis
Alpha and beta adrenergic
AV block
During cardiac arrest
Decrease BP
Bronchoconstriction

50. Adverse effects of Epinephrine
Hypertensive crisis
Dysrhythmias
Angina pectoris
Hyperglycemia
Necrosis

51. Adrenergic Agonists/ Receptors Stimulated
Isoproterenol: Beta 1 and 2
Dopamine: Dopamine, Beta 1, and Alpha 1 at high doses
Dobutamine: Beta 1
Phenylephrine: Alpha 1
Terbutaline: Beta 2
Ephedrine: Alpha 1nd 2, Beta 1 and 2

52. Indications (reason to give) of Adrenergic Antagonists
Blocks Sympathetic
Essential hypertension
Benign prostatic hyperplasia (BPH)
Pheocromocytoma
Raynaud’s disease (decreased circulation from vasoconstriction)

53. Adverse Effects of Alpha Adrenergic Antagonists
Blocks sympathetic
Orthostatic hypotension
Reflex tachycardia
Nasal congestion

54. Adrenergic - Uses Prazosin- HTN Terazosin- HTN and BPH_
Doxazosin- HTN and BPH
Tamsulosin- BPH
Phentolamine-vasodilation

55. Therapeutic Indications (reason to use)of Beta Adrenergic Antagonists
Angina pectoris
Hypertension
Cardiac Dysrhythmias

56. Adverse Effects of Beta Adrenergic Antagonists
Beta 1 blocked Causes:
Bradycardia
Reduced cardiac output
Precipitation of heart failure
AV heart block
Rebound cardiac excitation

57. Adverse Effects of Beta Adrenergic Antagonists
Beta 2 Blocked Causes:
Bronchoconstriction
Inhibition of glycogenolysis (increased blood sugar)

58. Beta Blockers Metoprolol Propanolol
Selective beta 1 blocker at therapeutic doses
Used for HTN, angina, heart failure, and MI
Propanolol
Non-selective beta blocker
Used for HTN, angina, cardiac dysrhythmias, and MI