Autonomic Nervous System Drugs Flashcards
Indications: Correction of hemodynamic imbalances present
in shock.
Actions: Acts directly and by the release of norepinephrine from sympathetic nerve terminals; mediates dilation of vessels in the renal and splanchnic beds to maintain renal perfusion while stimulating the sympathetic response.
Pharmacokinetics:
Route Onset Peak Duration
IV 1–2 min 10 min Length of infusion
T1/2: 2 minutes; metabolized in the liver, excreted in the urine.
Adverse effects: Tachycardia, ectopic beats, anginal pain,
hypotension, dyspnea, nausea, vomiting, headache.
Dopamine
Indications: Management of bronchospasm during anesthe-
sia; vasopressor during shock; adjunct in the management of
cardiac standstill and arrest, as well as serious ventricular
arrhythmias that require increased inotropic action.
Actions: Acts on beta-adrenergic receptors to produce
increased heart rate, positive inotropic effect, bronchodila-
tion, and vasodilation.
Pharmacokinetics:
Route Onset Duration
IV Immediate 1–2 min
T1/2: Unknown; metabolized in the tissues.
Adverse effects: Restlessness, apprehension, anxiety, fear, car-
diac arrhythmias, tachycardia, nausea, vomiting, heartburn, respiratory difficulties, coughing, pulmonary edema, sweating,
pallor.
Isoproterenol
This is sometimes considered a CNS stimulant, and although it does increase alertness, its actions and long-term consequences place it in a class by itself..
Nicotine
Indications: Hypertension, alone or in combination with other
drugs; off-label uses—control of blood pressure in pheochro-
mocytoma, clonidine-withdrawal hypertension.
Actions: Competitively blocks alpha- and beta-receptor sites
in the SNS, leading to lower blood pressure without reflex
tachycardia and decreased renin levels.
Pharmacokinetics:
Route Onset Peak Duration
Oral Varies 1–2 h 8–12 h
IV Immediate 5 min 5.5 h
T1/2: 6 to 8 hours, with hepatic metabolism and excretion in
the urine.
Adverse effects: Dizziness, vertigo, fatigue, gastric pain, flat-
ulence, impotence, bronchospasm, dyspnea, cough, decreased
exercise tolerance.
Labetalol
Indications: Prevention or control of hypertensive episodes
associated with pheochromocytoma; test for diagnosis of
pheochromocytoma; prevention and treatment of dermal
necrosis and sloughing associated with IV extravasation of
norepinephrine or dopamine.
Actions: Competitively blocks postsynaptic alpha1- and
presynaptic alpha2-receptors, causing a vasodilation and low-
ering of blood pressure, accompanied by increased reflex
tachycardia.
Pharmacokinetics:
Route Onset Peak Duration
Intramuscular Rapid 20 min 30–45 min
IV Immediate 2 min 15–30 min
T1/2: Metabolism and excretion are unknown.
Adverse effects: Acute and prolonged hypotensive episodes,
MI, tachycardia, arrhythmias, nausea, flushing.
Phentolamine
Prototype Summary: Doxazosin
Indications: Treatment of mild to moderate hypertension as
monotherapy or in combination with other antihypertensives;
treatment of BPH.
Actions: Reduces total peripheral resistance through alpha
blockade; does not affect heart rate or cardiac output; increases
high-density lipoproteins while lowering total cholesterol
levels.
Pharmacokinetics:
Route Onset Peak Duration
Oral Varies 2–3 h Not known
T1/2: 22 hours, with hepatic metabolism and excretion in the
bile, feces, and urine.
Adverse effects: Headache, fatigue, dizziness, postural dizzi-
ness, vertigo, tachycardia, edema, nausea, dyspepsia, diarrhea,
sexual dysfunction.
Doxazosin
Indications: Acute postoperative or postpartum nonobstruc-
tive urinary retention; neurogenic atony of the bladder with
retention.
Actions: Acts directly on cholinergic receptors to mimic the
effects of acetylcholine; increases tone of detrusor muscles
and causes emptying of the bladder.
Pharmacokinetics:
Route Onset Peak Duration
Oral 30–90 min 60–90 min 1–6 h
T1/2: Metabolism and excretion unknown; thought to be
synaptic.
Adverse effects: Abdominal discomfort, salivation, nausea,
vomiting, sweating, flushing.
Bethanechol
Also known as grass, pot, weed, reefer, and many
other names. This is a natural product obtained from C. Sativa.
Use of this slows motor activity decreases coordination, and causes disconnected thoughts, feelings of paranoia, and euphoria. It increases thirst and craving for food, particularly chocolate and other candies. One hallmark symptom is red or bloodshot eyes, caused by dilation of blood vessels.
Marijuana
Indications: Treatment of hypertension, angina pectoris, idio-
pathic hypertrophic subaortic stenosis (IHSS), supraventricu-
lar tachycardia, tremor; prevention of reinfarction after MI;
adjunctive therapy in pheochromocytoma; prophylaxis of
migraine headache; management of situational anxiety.
Actions: Competitively blocks beta-adrenergic receptors in
the heart and juxtaglomerular apparatus; reduces vascular tone
in the CNS.
Pharmacokinetics:
Route Onset Peak Duration
Oral 20–30 min 60–90 min 6–12 h
IV Immediate 1 min 4–6 h
T1/2: 3 to 5 hours with hepatic metabolism and excretion in
the urine.
Adverse effects: Allergic reaction, bradycardia, HF, cardiac
arrhythmias, cerebrovascular accident, pulmonary edema, gas-
tric pain, flatulence, impotence, decreased exercise tolerance,
bronchospasm.
Propranolol
also known as narcotic analgesics, are prescribed for severe pain, persistent cough, and diarrhea. The opioid class includes natural substances obtained from the unripe seeds of the poppy plant such as opium, morphine,
and codeine.
Opioids
Indications: Treatment of myasthenia gravis, antidote for
nondepolarizing neuromuscular junction blockers, increased
survival after exposure to nerve gas.
Actions: Reversible cholinesterase inhibitor that increases the
levels of acetylcholine, facilitating transmission at the neuro-
muscular junction.
Pharmacokinetics
Route Onset Duration
Oral 35–45 min 3–6 h
IM 15 min 3–6 h
IV 5 min 3–6 h
T1/2: 1.9 to 3.7 hours; metabolism is in the liver and tissue,
and excretion is in the urine.
Adverse effects: Bradycardia, cardiac arrest, tearing, miosis,
salivation, dysphagia, nausea, vomiting, increased bronchial
secretions, urinary frequency, and incontinence.
Pyridostigmine
Indications: Treatment of mild to moderate Alzheimer disease.
Actions: Reversible cholinesterase inhibitor that causes ele-
vated acetylcholine levels in the cortex, which slows the neu-
ronal degradation of Alzheimer disease.
Pharmacokinetics:
Route Onset Peak
Oral Varies 2–4 h
T1/2: 70 hours; metabolism is in the liver, and excretion is in
the urine.
Adverse effects: Insomnia, fatigue, rash, nausea, vomiting,
diarrhea, dyspepsia, abdominal pain, muscle cramps.
Donepezil
Usual Indications:
Adjunctive therapy to treat peptic ulcer, overactive GI disorders; neurogenic bladder or cystitis; parkinsonism; biliary or renal colic; to decrease
secretions preoperatively; treatment of partial heart block associated with vagal activity; treatment of rhinitis or anticholinesterase poisoning
Dosage/Route:
0.125–0.25 mg t.i.d. to q.i.d. PO or sublingually 0.25–0.5 mg b.i.d. to q.i.d. IM, IV or SC
Hyoscyamine (Anaspaz, Symax, others)
Indications: Treatment of angina pectoris, hypertension,
myocardial infarction; off-label uses are prevention of migraine
headaches, alcohol withdrawal syndrome, and supraventricular
tachycardias.
Actions: Blocks beta1-adrenergic receptors, decreasing the
excitability of the heart, cardiac output, and oxygen consump-
tion; decreases renin release, which lowers blood pressure.
Pharmacokinetics:
Route Onset Peak Duration
Oral Varies 2–4 h 24 h
IV Immediate 5 min 24 h
T1/2: 6 to 7 hours, with excretion in the bile, feces, and urine.
Adverse effects: Allergic reaction, dizziness, bradycardia, HF,
arrhythmias, gastric pain, flatulence, impotence, bron-
chospasm, decreased exercise tolerance.
Atenolol
Indications: Treatment of vascular failure in shock or drug-
induced hypotension; to overcome paroxysmal supraventric-
ular tachycardia; to prolong spinal anesthesia; as a vasocon-
strictor in regional anesthesia; to maintain blood pressure
during anesthesia; topically for symptomatic relief of nasal
congestion and as adjunctive therapy in middle ear infections;
ophthalmically to dilate pupils and as a decongestant to pro-
vide temporary relief of eye irritation.
Actions: Powerful postsynaptic alpha-adrenergic receptor stim-
ulant causing vasoconstriction and raising systolic and dias-
tolic blood pressure with little effect on the beta-receptors in
the heart.
Pharmacokinetics:
Route Onset Duration
IV Immediate 15–20 min
IM, SQ 10–15 min 30–120 min
Topically Very little systemic
absorption occurs
T1/2: 47 to 100 hours; metabolized in the tissues and liver;
excreted in urine and bile.
Adverse effects: Fear, anxiety, restlessness, headache, nausea,
decreased urine formation, pallor.
Phenylephrine
