1-1 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
Ach N Ach M3 Parasympathetic nerves Heart
M3 β2 M2
β1 α1 Exocrine glands Smooth muscle
Ach N NE Sympathetic nerves
Ach N Adrenal N Ach medulla Somatic nerves
Skeletal E and NE muscle in the blood
Cholinergic and adrenergic neurotransmission and sites of drug action. See back of card for description. 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 Cornea of muscarinic Trabecular receptor agonists meshwork Anterior chamber Iris Site of action of Schlemm canal prostaglandins
Episcleral vein
Lens
Ciliary Meridional Site of action of β-adrenoceptor processes ciliary muscle blockers, carbonic anhydrase inhibitors, α2-adrenoceptor Circular agonists, and epinephrine ciliary 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)
ATROPEN See Pharmacology, 5th ed., Chapter 7, pp. 73-75
Heart, smooth muscle, glands Acetylcholine Muscarinic receptors
Atropine 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 Can slow heart rate when first administered, a result of central Considerations 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)
TRACLEER See Pharmacology, 5th ed., Chapter 26, p. 309
Vascular smooth muscle
Endothelin-1 Endothelin-1 ETA & ETB receptors Bosentan 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)
DOBUTREX See Pharmacology, 5th ed., Chapter 8, pp. 86-87
Cardiac muscle Ca2ϩ Dobutamine b1, adrenoceptors Gs, cAMP, PKA
Gs ϭ G protein-s, cAMP ϭ cyclic adenosine monophosphate, PKA ϭ protein kinase A 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)
TENSILON See Pharmacology, 5th ed., Chapter 6, p. 66
Cholinesterase Acetylcholine Acetate ϩ Choline
Edrophonium 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)
ADRENALIN See Pharmacology, 5th ed., Chapter 8, p. 86-88
Vascular smooth muscle
a1- & b2- adrenoceptors
Epinephrine
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, respectively α1: vasoconstriction and increased blood pressure β1: increased heart rate, conduction, and contractility β2: 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)
FLOLAN See 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)
LOPRESSOR See Pharmacology, 5th ed., Chapter 9, pp. 96-99
Heart Epinephrine Norepinephrine b1-adrenoceptors
Metoprolol 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)
DEMSER See Pharmacology, 5th ed., Chapter 8, pp. 81-82; Chapter 10, p. 115
Tyrosine hydroxylase Tyrosine Dihydroxyphenylalanine (DOPA) Dopamine Norepinephrine
Metyrosine 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)
DIBENZYLINE See Pharmacology, 5th ed., Chapter 9, pp. 93-95
Vascular smooth muscle Epinephrine Norepinephrine a1- > a2-adrenoceptors
Phenoxybenzamine 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)
REGITINE See Pharmacology, 5th ed., Chapter 9, pp. 93-94
Vascular smooth muscle Epinephrine Norepinephrine a1- & a2-adrenoceptors
Phentolamine 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-SYNEPHRINE See Pharmacology, 5th ed., Chapter 8, p. 89
Vascular smooth muscle Muscle contraction
Phenylephrine a1-adrenoceptors Sarcoplasmic Ca2ϩ reticulum Gq, PKC, iP3
PKC ϭ protein kinase C, iP3 ϭ inositol triphosphate 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)
SALAGEN See Pharmacology, 5th ed., Chapter 6, p. 66
Salivary glands and ocular muscles Gland secretion
Pilocarpine Muscarinic M3 receptors Gq, PKC, IP3 Muscle contraction
PKC ϭ protein kinase C, lP3 ϭ 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 Useful in patients with xerostomia caused by radiation of head and Considerations 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)
PROTOPAM See 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)
INDERAL See Pharmacology, 5th ed., Chapter 9, pp. 96-99; Chapter 32, p. 32-35
Cardiac and smooth muscle Epinephrine Norepinephrine b1- & b2-adrenoceptors
Propranolol 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)
SUDAFED See 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)
MESTINON See Pharmacology, 5th ed., Chapter 6, p. 68
Cholinesterase Acetylcholine Acetate ϩ Choline
Pyridostigmine 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)
ZEMURON See Pharmacology, 5th ed., Chapter 7, pp. 76-78
Skeletal neuromuscular junction Acetylcholine Nicotinic receptors
Rocuronium 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)
VIAGRA See Pharmacology, 5th ed., Chapter 6, p. 70
Type 5 Phosphodiesterase Cyclic GMP 5Ј-GMP (inactive)
Sildenafil 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)
VESICARE See Pharmacology, 5th ed., Chapter 7, pp. 75-76
Urinary bladder muscle Acetylcholine Muscarinic receptors
Solifenacin 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)
ANECTINE See Pharmacology, 5th ed., Chapter 7, p. 78
Skeletal neuromuscular junction Acetylcholine Nicotinic receptors Prolonged Succinylcholine depolarization 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)
FLOMAX See Pharmacology, 5th ed., Chapter 9, pp. 95-96
Prostate & bladder muscle Epinephrine Norepinephrine a1A-adrenoceptors
Tamsulosin 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)
HYTRIN See Pharmacology, 5th ed., Chapter 9, pp. 94-96
Smooth muscle Epinephrine Norepinephrine a1-adrenoceptors
Terazosin 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