DRUGS ACTING ON THE ANS Flashcards
3 major divisions of the autonomic nervous system
sympathetic
parasympathetic
enteric nervous system (myenteric plexus, submucous plexus)
sympathetic:
spinal roots of origin
T1-T12
L1-L5
parasympathetic:
spinal roots of origin
CN 3, 7, 9, 10
sacrum
sympathetic:
location of ganglia
paravertebral chains of spinal column
parasympathetic:
location of ganglia
organs innervated, more distant from spinal cord
sympathetic:
preganglionic and postganglionic fibers
short, long
parasympathetic:
preganglionic and postganglionic fibers
long, short
primary transmitter at the sympathetic postganglionic neuron-effector cell synapses in most tissues
norepinephrine
exceptions of norepinephrine
eccrine sweat glands
vasodilator in the sympathetic fibers of skeletal muscles
primary transmitter in all autonomic ganglia and at the synapses between parasympathetic postganglionic neurons and their effector cells
acetylcholine
primary transmitter at the somatic skeletal muscle neurotransmitter junction
acetylcholine
- direct activation of adrenoceptors
- indirect activation by increasing concentration of available catecholamines in the synapse
sympathominetics
alpha-1 or alpha-2 adrenergic effect:
contraction of MOST vascular smooth muscle
alpha-1
alpha-1 or alpha-2 adrenergic effect:
stimulates glycogenolysis in the liver
alpha-1
alpha-1 or alpha-2 adrenergic effect:
stimulates aggregation of platelets
alpha-2
alpha-1 or alpha-2 adrenergic effect:
contraction of pupillary dilator muscle (mydriasis)
alpha-1
alpha-1 or alpha-2 adrenergic effect:
inhibits transmitter release in adrenergic and cholinergic nerve terminals
alpha-2
alpha-1 or alpha-2 adrenergic effect:
inhibits insulin release of pancreatic b cells
alpha-2
alpha-1 or alpha-2 adrenergic effect:
contraction of SOME vascular smooth muscle
alpha-2
alpha-1 or alpha-2 adrenergic effect:
contraction of pilomotor smooth muscle (erects hair)
alpha-1
alpha-1 or alpha-2 adrenergic effect:
inhibits lipolysis of fat cells
alpha-2
beta-1 or beta-2 adrenergic effect:
relaxes the airway, uterine, and vascular smooth muscle
beta-2
beta-1 or beta-2 adrenergic effect:
stimulates rate and force of heart
beta-1 and beta-2
beta-1 or beta-2 adrenergic effect:
stimulates glycogenolysis of liver
beta-2
beta-1 or beta-2 adrenergic effect:
causes tremors in the somatic motor neuron terminals
beta-2
beta-1 or beta-2 adrenergic effect:
stimulates renin release from juxtaglomerular cells of kidney
beta-1
beta-1 or beta-2 adrenergic effect:
stimulates insulin release from the pancreatic b cells
beta-2
6 classifications of sympathomimetics
- non-selective alpha agonist
- alpha-1 selective
- alpha-2 selective
- non-selective beta agonist
- beta-1 selective
- beta-2 selective
- sympathomimetic (non-selective)
- activates alpha and beta adrenergic receptors
- for cardiac arrest, anaphylaxis, asthma, copd, hemostasis
SE: HTN, tachycardia, ischemia, hyperglycemia
epinephrine
a1: vasoconstriction, increases BP
b1: increased HR, conduction and contractility
b2: bronchodilation
epinephrine
- sympathomimetic (non-selective)
- activates alpha, beta, and D1 adrenergic receptors
- for cardiogenic shock and heart failure
SE: cardiovascular disturbance, arrythmias
dopamine
a1: vasoconstriction, increases BP
b1: increased HR, conduction and contractility
D1: vasodilation in splanchnic and renal vessels
dopamine
- sympathomimetic (alpha-2 selective)
- activates a2 adrenergic receptors
- decreases central sympathetic outflow
- for HTN, cancer pain , opioid withdrawal
SE: sedation, rebound HTN, dry mouth
clonidine
in using clonidine, what should you do to avoid rebound hypertension
taper / gradually decrease use prior to discontinuation
what is the treatment for rebound HTN after using clonidine?
phentolamine
- sympathomimetic (alpha-2 selective)
- activates a2 adrenergic receptors
- decreases central sympathetic outflow
- used for preeclampsia, GHTN
SE: sedation, hemolytic anemia
methyldopa
- sympathomimetic (beta-2 selective)
- activates beta 2 receptors in bronchial smooth muscle causing bronchodilation
- used for acute asthma attack, tocolytic for preterm labor
SE: tachycardia, tremors, nervousness, restlessness, arrhythmias, loss of responsiveness
albuterol / salbutamol
drug choice for anaphylaxis
epinephrine
drug of choice for asthma attacks
albuterol / salbutamol
albuterol / salbutamol may precipitate ___ in patients with concurrent COPD and heart disease
arrhythmias
true or false: sympathomimetics are C/I in patients with cardiac dysrhythmias, narrow angle glaucoma, and cardiogenic shock
true
what should you monitor when administering sympathomimetics?
- VS and UO
- SE: tachycardia, palpitations, tremors, dizziness, HPN
continuous nasal spray can cause ___
nasal congestion rebound
alpha blockers
non-selective - irreversible
phenoxybenzamine
alpha blockers
non-selective - reversible
phentolamine
alpha blockers
alpha-1 selective
prazosin
alpha blockers
alpha-2 selective
yohimbine
beta blockers
non-selective
propranolol
beta blockers
beta-1 selective
atenolol
beta blockers
beta-2 selective
butoxamine
- adrenergic antagonist (alpha non-selective)
- irreversibly blocks alpha adrenergic receptors
phenoxybenzamine
used for pheochromocytoma (pre-surgical)
SE: orthostatic hypotension, reflex tachycardia, GI irritation, myocardial ischemia
phenoxybenzamine
forms covalent bond with alpha receptors = effects lasts for several days
phenoxybenzamine
- adrenergic antagonist (alpha non-selective)
- reversibly blocks alpha adrenergic receptors
SE: orthostatic hypotension, reflex tachycardia, GI irritation
phentolamine, tolazoline
- used for pheochromocytoma (pre-surgical)
- antidote to a1 antagonist overdose, rebound HTN
phentolamine, tolazoline
- adrenergic antagonist (alpha-1 selective)
- selectively blocks a1 adrenergic receptors
- used for benign prostatic hyperplasia, HTN
SE: 1st dose orthostatic hypotension, reflex tachycardia
prazosin
- adrenergic antagonist (beta non-selective)
- block b1 and b2 receptors
- block sympathetic effects on heart and BP
- reduce renin release
propranolol
- used for angina prophylaxis, HTN, arrhythmias, migraine, performance anxiety, hyperthyroidism
SE: bronchospasm, AV block, heart failure, CNS sedation, erectile dysfunction
propranolol
- may mask symptoms of hypoglycemia in diabetics
- carvedilol and labetalol has combines alpha and beta blockade (may be used for pheochromocytoma)
propranolol
- adrenergic antagonist (beta 1 selective)
- selectively block b1 receptors
- blocks sympathetic effects on heart and BP
- used for angina, HTN, heart failure
SE: bronchospasm, AV block, heart failure, CNS sedation, erectile dysfunction
atenolol
when administering adrenoceptor blockers, you should monitor?
VS, BP, and HR
when administering adrenoceptor blockers, report any complaint of ___
stuffy nose
when administering adrenoceptor blockers:
for clients with DM, have ___ available and follow adjustment of insulin dose as ordered
glucagon
true or false: when administering adrenoceptor blockers, quickly rise from supine to sitting / standing position
false - slowly rise
- not very useful for systemic therapy because their effects are not sufficiently selective
- parasympathetic and sympathetic ganglia and somatic junctions all may be blocked
cholinergic drugs
location of M1 cholinoreceptor
nerve endings
location of M2 cholinoreceptor
heart, some nerve endings
location of M3 cholinoreceptor
effector cells, smooth muscle glands, endothelium
location of Nn cholinoreceptor
ANS ganglia
location of Nm cholinoreceptor
neuromuscular end plate
- cholinergic (direct-acting)
- similar to carbachol
- active muscarinic receptors
- act on M receptor only
betanechol
- used for bladder and bowel atony (post-surgery or spinal cord injury)
- SE: cyclospasm, diarrhea, urinary urgency, vasodilation, reflex tachycardia, sweating
betanechol
- cholinomimetic (direct-acting)
- activates M3 receptors in ciliary muscle and salivary glands
- used for glaucoma, sjogren syndrome
- SE: miosis, blurring of vision
pilocarpine
autoimmune disorder characterized by triad of:
- xerostomia (dry mouth)
- xerophthalmia (dry eyes)
- rheumatoid arthritis
sjogren syndrome
- cholinomimetic (direct-acting)
- activates nicotinic ACH receptors (Nn and Nm)
- used for smoking cessation
- SE: generalized ganglionic stimulation
nicotine
nicotine overdose leads to?
convulsion, paralysis, coma
- CNS stimulation
- eye: miosis, spasm of accommodation
- lungs: bronchoconstriction
- GIT/GUT: excessive smooth muscle actiivity
- increased secretory activity
- vasodilation
muscarinic toxicity
- ganglionic stimulation
- blockade of neuromuscular end plate depolarization
- fasciculation and paralysis
- CNS toxicity: stimulation (convulsions) followed by CNS depression
nicotinic toxicity
- bind to cholinesterase and undergo prompt hydrolysis
- alcohol portion is released
- acidic portion is retained and release slowly
indirect-acting cholinomimetics
- prevents the binding and hydrolysis of endogenous acetylcholine
- amplify acetylcholine effects wherever ACH is released
indirect-acting cholinomimetics
- cholinomimetic (indirect-acting)
- inhibits acetylcholinesterase, amplifies endogenously released acetylcholine
- used for myasthenia gravis, differentiation of cholinergic crisis and myasthenic crisis
- SE: miosis, salivation, NV, diarrhea, bradycardia
edrophonium
true or false: edrophonium is known to be very short acting upon IV administration
true
how is myasthenia gravis diagnosed?
tensilon test
- cholinomimetic (indirect-acting)
- inhibits acetylcholinesterase, amplifies endogenously released acetylcholine
- used for myasthenia gravis, reversal of nondepolarizing neuromuscular blockade, glaucoma
- SE: miosis, salivation, NV, diarrhea, bradycardia
neostigmine
muscarinic effects caused by neostigmine are blocked by ___
atropine
autoimmune destruction of nictonic ACH receptors characterized by:
- fluctuating muscle weakness
- ocular symptoms
- bulbar symptoms
- proximal muscle weakness
myasthenia gravis
acute worsening of symptoms due to infection, stress or undermedication
myasthenic crisis
excessive activation of cholinoreceptors (skeletal muscle weakness and parasympathetic signs) due to overmedication
cholinergic crisis
how does edrophonium differentiate myasthenic crisis from cholinergic crisis?
myasthenic - IMPROVES muscle strength
cholinergic - WEAKENSS muscle strength
- prototype non-selective muscarinic blocker
- found in atropa belladona
- tertiary amine that readily crosses membrane barriers
atropine
- cholinergic antagonist
- competitively blocks all muscarinic receptors
- used for mydriatic, cycloplegic, antidote for organophosphate poisoning, bradycardia, hypersalivation
- SE: tachycardia, mydriasis, cycloplegia, skin flushing, delirium, hallucination
atropine
drug of choice for organophosphate poisoning
atropine
these can cause what?
malathion and parathion (insecticide)
sarin, tabun, soman: nerve gases
organophosphate poisoning
signs and symptoms of organophosphate poisoning
DUMBBELSS
diarrhea
urination
miosis
bronchospasm
bradycardia
excitation
lacrimation
sweating
salivation
- atropine fever
- atropine flush
- decreased secretion
- tachycardia
- arrhythmias
- constipation
- blurred vision
- CNS toxicity
atropine toxicity
- use cautiously in infants, may cause hyperthermia
- C/I: acute angle-closure glaucoma, benign prostatic hyperplasia
muscarinic blockers
