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Adrenergic and Cholinergic Drugs
Nervous System Central nervous system (brain and spinal cord) Peripheral nervous system (neurons outside the brain and spinal cord)
Efferent Afferent
nervous systemAutonomic nervous systemSomatic
nervous systemSympathetic (adrenergic)
Parasympatheticnervous system (cholinergic)
Functions of the ANS
- Involuntary System
- Responsible for:
- Control of smooth muscle (e.g., bronchi, blood vessels, GI tract), , )
- Cardiac muscle
- Exocrine glands (e.g., gastric, sweat, salivary)
- Monitored by both the sympathetic and parasympathetic nervous systems
Autonomic Nervous System
- Balanced antagonism between the sympathetic and parasympathetic nervous systems.
- A neurotransmitter needs to bind with an appropriate receptor site on the effector organ or tissue to produce effect
- This is accomplished by synaptic transmission.
Synaptic Transmission
- Synthesis of neurotransmitters in the
nerve terminal.
- Neurotransmitter is stored awaiting
an action potentialan action potential.
- Action potential causes release
- Neurotransmitter diffuses across the
synaptic gap
NE
Receptor Names
- Stimulated by Ach= Cholinergic
- Stimulated by NE= Adrenergic
Sympathetic Nervous System
- Mostly stimulated by NE
- Sympathomimetic
- Catacholamines
- Noncatecholamines
- Adrenergic receptors
Adrenergic Receptors
- Alpha-1, alpha-2, beta-1, and beta-2.
- Drugs that stimulate the receptors are called agonists.
- Drugs that block the receptors areD th t bl k th t called antagonists or blockers.
- Most drugs stimulate or block more than one receptor at a time.
- Some drugs are relatively selective in their stimulation or blockade.
Stimulation of Alpha-1 Receptors
- Stimulation causes:
- Vasoconstriction
- Increased peripheral resistance
- Increased blood pressure (BP)
- Pupil dilation (mydriasis)
- Closure of the internal sphincter of the bladder
- Blocking causes the opposite effects.
Which of the adrenergic receptors shuts off NE when stimulated?
A. Alpha 1 B. Alpha 2 C. Beta 1 D. Beta 2
Which of the following is in the sympathetic nervous system? a. Norepinephrine (NE) b. Dopamine (DA) c. Beta 2 receptors d. All of the above
Parasympathetic Nervous System
(PSNS)
- Acetylcholine is the neurotransmitter.
- Direct
- Indirect
Cholinergic Receptors
- Muscarinic:
- Concentrated in the heart, smooth muscle, and exocrine glands
- Nicotinic
- Found in the central nervous system (CNS), the neuromuscular junction, autonomic ganglia, and the adrenal medulla
A. PSNS stimulant B. PSNS agonist
Which of the following describes a
drug that stimulates the
parasympathetic system?
g C. Cholinergic D. All of the above
Anticholinergic Effects
- Increased intraocular pressure
- Mydriasis (dilation of pupils)
- Photophobiap
- Decreased sweating
- Dry mouth
- Decreased bronchial secretions
- Respiratory depression
Anticholinergic Effects (cont)
- Decreased GI motility with possible constipation
- Decreased BP followed by increased BP
- Tachycardia and, possibly, palpitationsT h di d ibl l it ti
- Urinary retention
- Vasodilation
- Drowsiness, confusion, and agitation
Excess Anticholinergic Mnemonics
- Mad as a hatter
- Blind as a bat
- Red as a beet
- Dry as a bone
Drug Actions
- Attaches to the neurotransmitter receptor sites
- Drug effect from stimulating/blocking receptor
ADRENERGIC Drugs Epinephrine
- Nonselective adrenergic agonist:
- Stimulates all alpha and beta receptors
Ask a nurse!
- Why would you want to give a drug that stimulates all alpha and beta receptors?
- What adverse effects would you expect to be common?
Put it together!
- Why don’t we just turn off infusion andj elevate the hand after infiltration of phenylephrine?
- Why is this different than if D5.45 NS infiltrates?
ADRENERGIC DRUGS
Phenylephrine
- Alpha-1 stimulant
- Potent vasoconstrictor
- Avoid IV extravasation
- Pharmacotherapeutics include:• Pharmacotherapeutics include:
- Vascular failure
- Hypotension
- Shock states
- Topical pharmacotherapeutics:
- Nasal decongestant
- Pupil dilation (mydriasis)
Prazosin Alpha-1 blocker
- What effect does the drug have on blood vessels? On blood pressure?
- What nursing actions are needed to minimize adverse effects?
ADRENERGIC DRUGS
Dopamine- Nonselective alpha 1 and
beta-1 stimulant
- Also stimulates dopaminergic receptorsAl ti l t d i i t
- Increases cardiac output
- Low doses- don’t see alpha 1 effects, just dopaminergic
- Higher doses see alpha 1 effects
Dopamine
- This is a catecholamine.
- How will you need to administer this drug?
ADRENERGIC DRUGS
Propranolol Nonspecific beta blocker Metoprolol- relatively selective for Beta 1
- Which type of adverse effects might be common to both of these drugs?
- Which adverse effects would be more likely to occur with propranolol?
CHOLINERGIC DRUGS
Neostigmine - Indirect-acting cholinergic
- Acts by reversibly inhibiting postsynaptic cholinesterasepostsynaptic cholinesterase (acetylcholinesterase)
- What serious adverse effects would be seen with an overdose?
- What would be the antidote?
CHOLINERGIC DRUGS
Atropine - Anticholinergic
- Anticholinergic effects
- Antidote to cholinergic poisoning
- Pharmacotherapeutics:
- Preoperatively to dry secretions
- Acute cardiac emergencies
- Topically (homatropine) to treat ophthalmic disorders
- Treatment of motion sickness and diarrhea
CHOLINERGIC DRUGS
Atropine - Anticholinergic
- What is responsible for adverse effects from this drug?from this drug?
- Which age group is most sensitive to anticholinergic adverse effects?
- What can the nurse do to minimize adverse effects?
Atropine (cont)
- Adverse effects related to loss of acetylcholine stimulation on receptors
- Most serious adverse effect:• Most serious adverse effect: anticholinergic overdose (poisoning)
Put it together!
Why is atropine ( anticholinergic )
given pre-op?
A. To cleanse the GI tract BB. To prevent aspiration of oralTo prevent aspiration of oral secretions C. To induce miosis D. To prevent motion sickness
