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1-11-1 Section I Autonomic, Autacoid, and Neuromuscular Drugs
Atropine Epoprostenol Phenylephrine Pyridostigmine Tamsulosin
Bosentan Metoprolol Pilocarpine Rocuronium Terazosin
Dobutamine Metyrosine Pralidoxime Sildenafil
Edrophonium Phenoxybenzamine Propranolol Solifenacin
Epinephrine Phentolamine Pseudoephedrine Succinylcholine
Cholinergic and adrenergic neurotransmission and sites of drug action. See figure on back of card. In skeletal muscle, acetylcholine (Ach) activates nicotinic (N) receptors causing muscle contraction. Neuromuscular blockers (rocuronium) compete with Ach for N receptors and cause muscle relaxation. In smooth muscle and glands, Ach and pilocarpine activate muscarinic (M) receptors, causing muscle contraction and gland secretion. M receptor antagonists (atropine) cause muscle relaxation and inhibit secretions. Norepinephrine (NE) and epinephrine (E) activate α and β adrenoceptors and cause smooth muscle contraction or relaxation, respectively. Activation of cardiac β-receptors leads to increased heart rate, contractility, and conduction velocity. α-Blockers (terazosin) relax vascular and bladder smooth muscle, whereas β-blockers (propranolol) slow heart rate and decrease cardiac output and blood pressure. (α = alpha, β = beta.)
1-2 Autonomic, Autacoid, and Neuromuscular Drugs
Cholinergic and adrenergic neurotransmission and sites of drug action. See back of card for description.
M2
M3
β1
Smoothmuscle
α1
β2
AchAch N
Parasympathetic nerves
Sympathetic nerves
Ach N
Ach
Ach
E and NEin the blood
Skeletalmuscle
Exocrine glands
Heart
Adrenalmedulla
Somatic nerves
NE
N
N
M3
1-3 Autonomic, Autacoid, and Neuromuscular Drugs
Sites of action of drugs used in treating glaucoma. See figure on back of card. Aqueous humor is secreted by the ciliary process and flows through the pupillary aperture of the iris into the anterior chamber. It then drains through the trabecular meshwork into the venous sinus of sclera (Schlemm canal). In persons with open-angle glaucoma, elevated intraocular pressure, often resulting from decreased aqueous humor outflow, may lead to the gradual loss of peripheral vision. Drugs can be used to reduce intraocular pressure before irreversible optic nerve damage occurs. Muscarinic receptor agonists (pilocarpine) cause contraction of ciliary muscle fibers that insert near the trabecular meshwork, which opens the trabecular spaces so that aqueous humor drains more easily. Prostaglandins (latanoprost) increase aqueous drainage through the uveoscleral route in which aqueous humor flows through the ciliary muscles into the suprachoroidal space. The β-adrenoceptor blockers (timolol) and the α2-adrenoceptor agonists (apraclonidine) reduce the formation of cyclic adenosine monophosphate (cAMP), a substance that stimulates aqueous humor production. Carbonic anhydrase inhibitors (dorzolamide) reduce formation of bicarbonate, a substance required for aqueous humor secretion. (α = alpha, β = beta.)
1-4 Autonomic, Autacoid, and Neuromuscular Drugs
Site of action of β-adrenoceptor blockers, carbonic anhydrase
inhibitors, α2-adrenoceptor agonists, and epinephrine
Site of actionof muscarinic
receptor agonists
Site of action ofprostaglandins
CorneaTrabecularmeshwork
Anterior chamber
Schlemm canalIris
Lens
Episcleral vein
Ciliaryprocesses
Circularciliary muscle
Meridionalciliary muscle
Sites of action of drugs used in treating glaucoma. See other side for description.
1-5 Autonomic, Autacoid, and Neuromuscular Drugs
Atropine(at-roe-peen)
ATROPENSee Pharmacology, 5th ed., Chapter 7, pp. 73-75
Acetylcholine
Atropine
Muscarinic receptors
Heart, smooth muscle, glands
1-6 Atropine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Anticholinergic agent
Pharmacologic Class Muscarinic acetylcholine receptor antagonist
MOA Competitively blocks all muscarinic receptors, increases heart rate and conduction velocity, causes smooth muscle relaxation, and decreases exocrine gland secretion
Clinical Use Treatment (Tx) of bradycardia and atrioventricular block; Tx of irritable bowel symptoms; Tx of anticholinesterase poisoning; antisecretory agent (glycopyrrolate often used for this purpose in surgery); Tx of ocular inflammation (relaxes iris and ciliary muscles)
Special Considerations
Can slow heart rate when first administered, a result of central vagal stimulation
Adverse Effects Tachycardia; mydriasis and cycloplegia; warm, dry, flushed skin; delirium; and hallucinations
Interactions Additive anticholinergic effects with antihistamines (diphenhydramine) and tricyclic antidepressants (amitriptyline); slows absorption of other drugs by delaying gastric emptying
Similar drugs: Darifenacin, dicyclomine, glycopyrrolate, hyoscyamine, ipratropium, oxybutynin, solifenacin, scopolamine, tolterodine, trospium
1-7 Autonomic, Autacoid, and Neuromuscular Drugs
Bosentan(boe-sen-tan)
TRACLEERSee Pharmacology, 5th ed., Chapter 26, p. 309
Endothelin-1
Bosentan
Endothelin-1 ETA & ETBreceptors
Vascular smooth muscle
1-8 Bosentan Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Vasodilator drug
Pharmacologic Class Endothelin-1 receptor antagonist
MOA Blocks endothelinA (ETA) and endothelinB (ETB) receptors in vascular smooth muscle, causing vasodilation
Clinical Use Treatment of pulmonary arterial hypertension: decreases pulmonary vascular resistance and dyspnea; improves walking distance
Special Considerations Likely to cause birth defects; contraindicated in pregnancy
Adverse Effects Elevated serum aminotransferase levels
Interactions Inhibitors of cytochrome P450 2C9 (CYP2C9) or CYP3A4 (e.g., cyclosporine) elevate bosentan levels; bosentan induces CYP2C9 and CYP3A4 and decreases levels of affected drugs
Similar drugs: Ambrisentan, macitentan
1-9 Autonomic, Autacoid, and Neuromuscular Drugs
Dobutamine(doe-bue-ta-meen)
DOBUTREXSee Pharmacology, 5th ed., Chapter 8, pp. 86-87
Dobutamine b1, adrenoceptors
Cardiac muscle
Gs � G protein-s, cAMP � cyclic adenosine monophosphate,PKA � protein kinase A
Gs, cAMP, PKA
Ca2�
1-10 Dobutamine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Sympathomimetic; cardiac stimulant
Pharmacologic Class Selective β1-adrenoceptor agonist
MOA Activates β1-receptors > β2-receptors ≫ α1-receptors; increases phosphorylation of calcium channels and calcium Influx; increases cardiac contractility and cardiac output > heart rate
Clinical Use Treatment of acute heart failure and cardiogenic shock
Special Considerations Administered by intravenous infusion; must correct hypovolemia before giving dobutamine
Adverse Effects Tachycardia and arrhythmia
Interactions Synergistic effect on cardiac output with nitroprusside (a vasodilator that decreases cardiac afterload)
Similar drugs: None
1-11 Autonomic, Autacoid, and Neuromuscular Drugs
Edrophonium(ed-roe-foe-nee-um)
TENSILONSee Pharmacology, 5th ed., Chapter 6, p. 66
Edrophonium
CholinesteraseAcetate � CholineAcetylcholine
1-12 Edrophonium Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Diagnostic agent
Pharmacologic Class Cholinesterase inhibitor
MOA Reversibly inhibits cholinesterase; increases acetylcholine levels at neuroeffector junctions
Clinical Use Diagnosis of myasthenia gravis (MG); increases muscle strength in persons with MG but increases weakness in MG patients treated with excessive doses of a cholinesterase inhibitor; used to reverse effects of curariform-type neuromuscular blocking agents such as rocuronium
Special Considerations Very short-acting after intravenous administration
Adverse Effects Muscarinic effects (e.g., miosis, salivation) can be treated with atropine
Interactions None usually significant
Similar drugs: Neostigmine, physostigmine, pyridostigmine
1-13 Autonomic, Autacoid, and Neuromuscular Drugs
Epinephrine(e-pi-nef-rin)
ADRENALINSee Pharmacology, 5th ed., Chapter 8, p. 86-88
Epinephrine
a1- & b2-adrenoceptors
Vascular smooth muscle
b1-adrenoceptors
Cardiac tissue
1-14 Epinephrine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Vasopressor; bronchodilator
Pharmacologic Class Nonselective adrenoceptor agonist
MOA Activates α- and β-receptors, increasing inositol triphosphate and cyclic adenosine monophosphate, respectivelyα1: vasoconstriction and increased blood pressureβ1: increased heart rate, conduction, and contractilityβ2: vasodilation and decreased diastolic blood pressure; bronchodilation
Clinical Use Treatment (Tx) of cardiac arrest; ventricular fibrillation; anaphylactic shock; Tx of asthma and chronic obstructive pulmonary disease; prolongs duration of local anesthetics
Adverse Effects Hypertension; tachycardia; ischemia; hyperglycemia
Interactions None usually significant
Similar drugs: Norepinephrine (does not activate β2-receptors significantly)
1-15 Autonomic, Autacoid, and Neuromuscular Drugs
Epoprostenol(e-poe-pros-te-nole)
FLOLANSee Pharmacology, 5th ed., Chapter 26, pp. 308-309
1-16 Epoprostenol Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Vasodilator
Pharmacologic Class Naturally occurring prostacyclin (PGI2)
MOA Activates prostaglandin IP receptors, causing vascular smooth muscle relaxation and vasodilation; increases pulmonary blood flow and reduces dyspnea
Clinical Use Treatment of pulmonary arterial hypertension (PAH); administered via central venous catheter
Special Considerations Treprostinil is a stable prostacyclin analogue administered by subcutaneous infusion pump that reduces dyspnea and improves physical activity in PAH patients; selexipag is an orally administered prostacyclin IP receptor agonist for treating PAH
Adverse Effects Flushing, hypotension, tachycardia, diarrhea, nausea, vomiting, flulike symptoms
Interactions None usually significant
Similar drugs: Treprostinil, selexipag
1-17 Autonomic, Autacoid, and Neuromuscular Drugs
Metoprolol(meh-toh-pruh-lawl)
LOPRESSORSee Pharmacology, 5th ed., Chapter 9, pp. 96-99
EpinephrineNorepinephrine
Metoprolol
b1-adrenoceptors
Heart
1-18 Metoprolol Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Sympatholytic; antihypertensive
Pharmacologic Class Selective β1-adrenoceptor antagonist
MOA Competitively blocks β-adrenoceptors; decreases heart rate, cardiac output, renin secretion, blood pressure, and myocardial oxygen demand
Clinical Use Treatment of angina and hypertension; post–myocardial infarction to reduce mortality
Special Considerations Given orally or intravenously; lacks local anesthetic or partial agonist activity
Adverse Effects Bronchoconstriction with higher doses because of β2-receptor blockade
Interactions Additive hypotensive effect with nitrates and antihypertensive drugs; additive bradycardia with digoxin; decreases effects of dopamine and dobutamine; unopposed α-adrenergic receptor stimulation with epinephrine and related drugs
Similar drugs: Bisoprolol
1-19 Autonomic, Autacoid, and Neuromuscular Drugs
Metyrosine(me-tyre-o-seen)
DEMSERSee Pharmacology, 5th ed., Chapter 8, pp. 81-82; Chapter 10, p. 115
Metyrosine
Tyrosine hydroxylaseDihydroxyphenylalanine (DOPA) Dopamine NorepinephrineTyrosine
1-20 Metyrosine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Sympatholytic
Pharmacologic Class Tyrosine hydroxylase inhibitor
M.O.A. Inhibits norepinephrine and epinephrine synthesis
Clinical Use Reduction of blood pressure and heart rate in patients with pheochromocytoma; used preoperatively, or chronically for inoperable tumors; often combined with phenoxybenzamine
Adverse Effects Hypotension, bradycardia
Interactions Additive effects with α- and β-adrenoceptor antagonists
Similar drugs: None
1-21 Autonomic, Autacoid, and Neuromuscular Drugs
Phenoxybenzamine(fen-ox-i-benz-a-meen)
DIBENZYLINESee Pharmacology, 5th ed., Chapter 9, pp. 93-95
EpinephrineNorepinephrine
Phenoxybenzamine
a1- > a2-adrenoceptors
Vascular smooth muscle
1-22 Phenoxybenzamine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Vasodilator
Pharmacologic Class Irreversible α-adrenoceptor antagonist
MOA Blocks α1-receptors > α2-receptors; forms covalent bond with α-receptor and causes irreversible receptor blockade
Clinical Use Presurgical treatment of hypertension caused by pheochromocytoma
Special Considerations Effects last several days
Adverse Effects Postural hypotension
Interactions Hypotensive effect increased by β-adrenoceptor blockers and calcium channel blockers
Similar drugs: Phentolamine
1-23 Autonomic, Autacoid, and Neuromuscular Drugs
Phentolamine(fen-toe-la-meen)
REGITINESee Pharmacology, 5th ed., Chapter 9, pp. 93-94
EpinephrineNorepinephrine
Phentolamine
a1- & a2-adrenoceptors
Vascular smooth muscle
1-24 Phentolamine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Vasodilator
Pharmacologic Class Nonselective α-adrenoceptor antagonist
MOA Competitive, reversible antagonist of α1- and α2-receptors causing vasodilation
Clinical Use Counteracts vasoconstriction caused by accidental injection or extravasation of epinephrine and other vasoconstrictors; control of blood pressure during surgery for pheochromocytoma
Special Considerations Parenteral administration only; short duration of action
Adverse Effects Hypotension
Interactions Severe hypotension if given with epinephrine; blocks effects of α-adrenoceptor agonists
Similar drugs: Phenoxybenzamine
1-25 Autonomic, Autacoid, and Neuromuscular Drugs
Phenylephrine(fen-il-ef-rin)
NEO-SYNEPHRINESee Pharmacology, 5th ed., Chapter 8, p. 89
Phenylephrine a1-adrenoceptors
Vascular smooth muscle Muscle contraction
PKC � protein kinase C, iP3 � inositol triphosphate
Sarcoplasmicreticulum
Gq, PKC, iP3Ca2�
1-26 Phenylephrine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Vasoconstrictor; decongestant
Pharmacologic Class Selective α1-adrenoceptor agonist
MOA Activates α1-receptors, increasing inositol triphosphate via protein kinase C activation, and causing release of calcium and contraction of vascular smooth muscle and vasoconstriction
Clinical Use Nasal and ocular decongestant; treatment of drug-induced hypotension and spinal shock; dilation of pupil for ophthalmoscopy; local hemorrhoid treatment
Special Considerations Ocular administration causes mydriasis without cycloplegia (paralysis of accommodation)
Adverse Effects Rebound nasal congestion if used topically more than 3 days; hypertension
Interactions May cause severe hypertension if given with monoamine oxidase inhibitors; vasopressor effect increased by tricyclic antidepressants
Similar drugs: Norepinephrine, pseudoephedrine
1-27 Autonomic, Autacoid, and Neuromuscular Drugs
Pilocarpine(pye-loe-car-peen)
SALAGENSee Pharmacology, 5th ed., Chapter 6, p. 66
Pilocarpine Muscarinic M3 receptors
Salivary glands and ocular muscles
Gland secretion
Muscle contraction
Gq, PKC, IP3
PKC � protein kinase C, lP3 � phospho-inositol
1-28 Pilocarpine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Antiglaucoma agent; sialagogue
Pharmacologic Class Muscarinic acetylcholine receptor agonist
MOA Activates muscarinic receptors in ciliary muscle, increasing aqueous humor outflow; activates muscarinic receptors in salivary gland, increasing salivation
Clinical Use Treatment of glaucoma (topical ocular administration) and dry mouth (xerostomia) by oral administration
Special Considerations
Useful in patients with xerostomia caused by radiation of head and neck and Sjögren syndrome (arthritis, dry eyes, dry mouth)
Adverse Effects Miosis, blurred vision (accommodative spasm) caused by excessive contraction of iris sphincter and ciliary muscles, respectively
Interactions Additive effects with other cholinergic drugs; effects decreased by atropine and other anticholinergic drugs
Similar drugs: Cevimeline
1-29 Autonomic, Autacoid, and Neuromuscular Drugs
Pralidoxime(pral-i-dox-ime)
PROTOPAMSee Pharmacology, 5th ed., Chapter 6, p. 70
1-30 Pralidoxime Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Organophosphate antidote
Pharmacologic Class Cholinesterase reactivator
MOA Binds phosphorus of organophosphate and breaks bond with cholinesterase
Clinical Use Treatment of organophosphate toxicity (used to reverse muscle weakness)
Special Considerations Give as soon as possible after organophosphate exposure (before aging of organophosphate-cholinesterase bond prevents reactivation)
Adverse Effects When treating organophosphate poisoning, it is difficult to differentiate the toxic effects of pralidoxime from those produced by atropine or organophosphate compounds
Interactions When used with atropine, signs of atropinization occur earlier than when atropine is used alone
Similar drugs: None
1-31 Autonomic, Autacoid, and Neuromuscular Drugs
Propranolol(proe-pran-oh-lol)
INDERALSee Pharmacology, 5th ed., Chapter 9, pp. 96-99; Chapter 32, p. 32-35
EpinephrineNorepinephrine
Propranolol
b1- & b2-adrenoceptors
Cardiac and smooth muscle
1-32 Propranolol Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Sympatholytic; antihypertensive
Pharmacologic Class Nonselective β-adrenoceptor antagonist
MOA Competitively blocks β1- and β2-receptors; decreases heart rate, cardiac output, blood pressure, myocardial oxygen demand
Clinical Use Treatment of angina, cardiomyopathy, hypertension, thyrotoxicosis, and benign tremor; migraine prophylaxis
Special Considerations Highly lipophilic, causing central nervous system side effects; local anesthetic activity prevents ocular use
Adverse Effects Bronchoconstriction; inhibits glycogenolysis; nightmares and mood depression
Interactions Additive hypotensive effect with nitrates and antihypertensive drugs; additive bradycardia with digoxin; decreases effects of dopamine and dobutamine; causes unopposed α-adrenoceptor stimulation with epinephrine and related drugs
Similar drugs: Nadolol, pindolol, timolol
1-33 Autonomic, Autacoid, and Neuromuscular Drugs
Pseudoephedrine(soo-doe-e-fed-rin)
SUDAFEDSee Pharmacology, 5th ed., Chapter 8, pp. 90-91
1-34 Pseudoephedrine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Decongestant
Pharmacologic Class Indirect- and direct-acting adrenoceptor agonist
MOA Increases release of norepinephrine and directly activates adrenoceptors, causing vasoconstriction and cardiac stimulation
Clinical Use Administered orally as nasal decongestant for allergic and viral rhinitis and sinusitis
Special Considerations Use is restricted to prevent diversion for methamphetamine synthesis
Adverse Effects Tachycardia; increased blood pressure; central nervous system stimulation
Interactions Concurrent use with monoamine oxidase (MAO) inhibitors causes severe hypertension; urine acidification or alkalinization increases or decreases excretion, respectively
Similar drugs: Norepinephrine, phenylephrine
1-35 Autonomic, Autacoid, and Neuromuscular Drugs
Pyridostigmine(peer-i-doe-stig-meen)
MESTINONSee Pharmacology, 5th ed., Chapter 6, p. 68
Pyridostigmine
CholinesteraseAcetate � CholineAcetylcholine
1-36 Pyridostigmine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Antimyasthenic agent
Pharmacologic Class Cholinesterase inhibitor; indirect-acting cholinergic agonist
MOA Reversibly inhibits cholinesterase; increases acetylcholine levels at neuroeffector junctions
Clinical Use Treatment of myasthenia gravis (severe muscle weakness); reversal of nondepolarizing neuromuscular blockers such as vecuronium during surgery
Special Considerations Muscarinic effects blocked by atropine
Adverse Effects Muscarinic effects (e.g., miosis, salivation)
Interactions Prolongs effects of succinylcholine; effects reduced by atropine, antidepressants, phenothiazine drugs, quinidine, and other drugs with anticholinergic effects
Similar drugs: Edrophonium, neostigmine
1-37 Autonomic, Autacoid, and Neuromuscular Drugs
Rocuronium(roe-cue-roe-nee-um)
ZEMURONSee Pharmacology, 5th ed., Chapter 7, pp. 76-78
Acetylcholine
Rocuronium
Nicotinic receptors
Skeletal neuromuscularjunction
1-38 Rocuronium Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Paralytic agent
Pharmacologic Class Nondepolarizing neuromuscular blocking agent
MOA Competitively blocks nicotinic receptors in skeletal muscle; has little effect on autonomic ganglia
Clinical Use Skeletal muscle relaxation for intubation, surgery, and electroconvulsive therapy; 30- to 60-min duration of action
Special Considerations Effects reversed by neostigmine, pyridostigmine, and edrophonium; effects more rapidly reversed by sugammadex
Adverse Effects Respiratory muscle paralysis and apnea
Interactions Effects potentiated by anesthetics, Ca2+ channel blockers, tetracycline, and aminoglycoside antibiotics
Similar drugs: Vecuronium, pancuronium
1-39 Autonomic, Autacoid, and Neuromuscular Drugs
Sildenafil(sil-den-a-fil)
VIAGRASee Pharmacology, 5th ed., Chapter 6, p. 70
Sildenafil
Type 5 Phosphodiesterase5�-GMP (inactive)Cyclic GMP
1-40 Sildenafil Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Vasodilator
Pharmacologic Class Phosphodiesterase inhibitor
MOA Inhibits type-5 phosphodiesterase breakdown of cyclic guanosine monophosphate and increases vasodilation in corpus cavernosum evoked by acetylcholine-mediated release of nitric oxide
Clinical Use Treatment (Tx) of erectile dysfunction; Tx of pulmonary arterial hypertension
Special Considerations Tadalafil and vardenafil also used to treat urinary symptoms of benign prostatic hyperplasia; tadalafil also approved for pulmonary arterial hypertension
Adverse Effects Headache; nasal congestion; back pain; visual disturbances; concurrent use with organic nitrates can cause profound hypotension, reflex tachycardia, angina, and death
Interactions Potentiates vasodilation produced by organic nitrates; serum levels increased by cytochrome P450 3A4 (CYP3A4) inhibitors
Similar drugs: Avanafil, tadalafil, vardenafil
1-41 Autonomic, Autacoid, and Neuromuscular Drugs
Solifenacin(sol-ee-fen-a-sin)
VESICARESee Pharmacology, 5th ed., Chapter 7, pp. 75-76
Acetylcholine
Solifenacin
Muscarinic receptors
Urinary bladder muscle
1-42 Solifenacin Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Overactive bladder (OAB) agent
Pharmacologic Class Muscarinic receptor antagonist
MOA Competitively blocks muscarinic acetylcholine receptors in the urinary bladder and elsewhere; relaxes urinary bladder smooth muscle
Clinical Use Treatment of OAB: relieves urgency, incontinence, and frequency while increasing voided volume per micturition
Special Considerations Once-daily oral administration with or without food; oxybutynin available as a topical gel for OAB
Adverse Effects Dry mouth, constipation, blurred vision (accommodation abnormalities), urinary retention, and dry eyes
Interactions Metabolized by CYP3A4; strong inhibitors of CYP3A4 (ketoconazole) increase serum levels, and lowest dose of solifenacin should be employed if given concurrently
Similar drugs: Darifenacin, oxybutynin, tolterodine, trospium
1-43 Autonomic, Autacoid, and Neuromuscular Drugs
Succinylcholine(sux-sin-il-koe-leen)
ANECTINESee Pharmacology, 5th ed., Chapter 7, p. 78
Acetylcholine
Succinylcholine
Nicotinic receptors
Skeletal neuromuscularjunction
Prolongeddepolarization
1-44 Succinylcholine Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Paralytic agent
Pharmacologic Class Depolarizing neuromuscular blocker
MOA Binds to nicotinic receptors, causing persistent depolarization of skeletal muscle and muscle paralysis; rapidly metabolized by plasma cholinesterase; short duration of action (5-10 min)
Clinical Use Short-term skeletal muscle relaxation for intubation and surgery; often preferred for intubation owing to short duration of action
Special Considerations Causes transient muscle fasciculations; effects are not reversed by neostigmine or edrophonium (unlike those of rocuronium and other curariform drugs)
Adverse Effects Respiratory muscle paralysis and apnea, especially in persons with rare atypical cholinesterase
Interactions Neuromuscular blockade enhanced by aminoglycoside antibiotics, clindamycin, amphotericin B, quinidine, and cholinesterase inhibitors
Similar drugs: None
1-45 Autonomic, Autacoid, and Neuromuscular Drugs
Tamsulosin(tam-soo-loe-sin)
FLOMAXSee Pharmacology, 5th ed., Chapter 9, pp. 95-96
EpinephrineNorepinephrine
Tamsulosin
a1A-adrenoceptors
Prostate & bladder muscle
1-46 Tamsulosin Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Urologic agent
Pharmacologic Class Uroselective α1-adrenoceptor antagonist
MOA Competitively blocks α1A-receptors in bladder and prostate; relaxes prostatic and bladder smooth muscle and facilitates bladder emptying
Clinical Use Treatment of urinary tract symptoms of benign prostatic hyperplasia: urinary frequency, urgency, and nocturia (the need to urinate more frequently at night)
Special Considerations Alfuzosin, silodosin, and tamsulosin are not indicated for treatment of hypertension
Adverse Effects Dizziness; headache; postural hypotension
Interactions Cimetidine may increase blood levels and effects
Similar drugs: Alfuzosin, silodosin
1-47 Autonomic, Autacoid, and Neuromuscular Drugs
Terazosin(ter-az-oh-sin)
HYTRINSee Pharmacology, 5th ed., Chapter 9, pp. 94-96
EpinephrineNorepinephrine
Terazosin
a1-adrenoceptors
Smooth muscle
1-48 Terazosin Autonomic, Autacoid, and Neuromuscular Drugs
Therapeutic Class Antihypertensive agent; urologic agent
Pharmacologic Class α1-adrenoceptor antagonist
MOA Competitively blocks α1A and α1B-receptors; relaxes arteriolar smooth muscle and decreases vascular resistance and blood pressure; relaxes prostatic and bladder smooth muscle to facilitate emptying of bladder
Clinical Use Treatment of hypertension and urinary symptoms caused by prostatic hyperplasia
Special Considerations Less selective for prostatic smooth muscle than selective α1A blockers such as alfuzosin, silodosin, and tamsulosin
Adverse Effects Hypotension; first-dose syncope; start with low dose and gradually increase
Interactions Additive hypotensive effect with diuretics and other antihypertensive drugs
Similar drugs: Doxazosin
I Autonomic, Autacoid, and Neuromuscular DrugsAtropineBosentanDobutamineEdrophoniumEpinephrineEpoprostenolMetoprololMetyrosinePhenoxybenzaminePhentolaminePhenylephrinePilocarpinePralidoximePropranololPseudoephedrinePyridostigmineRocuroniumSildenafilSolifenacinSuccinylcholineTamsulosinTerazosin