USMLE STEP 1 Pharmacology
What are the major functions of the α1 receptor? - correctanswerIncrease vascular
smooth muscle contraction, increase pupillary dilator muscle contraction (mydriasis),
increase intestinal and bladder sphincter muscle contraction
What are the major functions of the α2 receptor? - correctanswerDecrease sympathetic
outflow, decrease insulin release, decrease lipolysis, increase platelet aggregation,
decrease aqueous humor production
What are the major functions of the β1 receptor? - correctanswerIncrease heart rate,
increase contractility, increase renin release, increase lipolysis
What are the major functions of the β2 receptor? - correctanswerVasodilation,
bronchodilation, increase lipolysis, increase insulin release, decrease uterine tone
(tocolysis), ciliary muscle relaxation, increase aqueous humor production
What are the major functions of the M1 receptor? - correctanswerCNS, enteric nervous
system
What are the major functions of the M2 receptor? - correctanswerDecrease heart rate
and contractility of atria
What are the major functions of the M3 receptor? - correctanswerIncrease exocrine
gland secretions (e.g., lacrimal, salivary, gastric acid), increase gut peristalsis, increase
bladder contraction, increase bronchoconstriction, pupillary sphincter muscle
contraction (miosis), ciliary muscle contraction (accommodation)
What are the major functions of the D1 receptor? - correctanswerRelaxes renal vascular
smooth muscle
What are the major functions of the D2 receptor? - correctanswerModulates transmitter
release, especially in the brain
What are the major functions of the H1 receptor? - correctanswerIncrease nasal and
bronchial mucus production, increase vascular permeability, contraction of bronchioles,
pruritis, pain
What are the major functions of the H2 receptor? - correctanswerIncrease gastric acid
secretion
What are the major functions of the V1 receptor? - correctanswerIncrease vascular
smooth muscle contraction
,What are the major functions of the V2 receptor? - correctanswerIncrease H2O
permeability and reabsorption in collecting tubules of kidney (V2 is found in the "2"
kidneys)
What receptors are associate with Gq? - correctanswerH1, α1, V1, M1, and M3
What receptors are associated with Gs? - correctanswerH2, B1, B2, V2, D1
What receptors are associated with Gi? - correctanswerM2, α2, D2
Bethanechol - correctanswer-Direct cholinergic agonist
-Activates bowel and bladder smooth muscle
-Used in postoperative and neurogenic ileus
-Resistant to AChE
Carbachol - correctanswer-Direct cholinergic agonist
-Carbon copy of acetylcholine
-Constricts pupils and relieves intraocular pressure in glaucoma
Methacholine - correctanswer-Direct cholinergic agonist
-Stimulates muscarinic receptors in airways when inhaled
-Used as a challenge test for diagnosis of asthma
Pilocarpine - correctanswer-Direct cholinergic agonist
-Contracts ciliary muscle of eye (open angle glaucoma), contracts pupillary sphincter
(closed angle glaucoma)
-Potent stimulator of sweat, tears and saliva
-AChE resistant
Donepezil - correctanswer-Anticholinesterse - increases ACh
-Alzheimer disease
Galantamine - correctanswer-Anticholinesterse - increases ACh
-Alzheimer disease
Rivastigmine - correctanswer-Anticholinesterse - increases ACh
-Alzheimer disease
Edrophonium - correctanswer-Anticholinesterse - increases ACh
-Historically used to diagnose myasthenia gravis (MG is now diagnosed by anti-AChR
Ab test.
Neostigmine - correctanswer-Anticholinesterse - increases ACh
-Used in postoperative and neurogenic ileus and urinary retention, myasthenia gravis,
and postoperative reversal of neuromuscular junction blockade
,Physostigmine - correctanswer-Anticholinesterse - increases ACh
-Used in anticholinergic toxicity
-Crosses the blood-brain barrier (CNS)
Pyridostigmine - correctanswer-Anticholinesterse - increases ACh
-Increases muscle strength
-Used in myasthenia gravis (long acting)
-Does not penetrate CNS
Atropine - correctanswer-Muscarinic antagonist
-Used in bradycardia and for ophthalmic applications
-Also used as antidote for cholinesterase inhibitor poisoning
-Actions include increase pupil dilation, cycloplegia, decreased airway secretions,
decreased acid secretions, decreased gut motility, decreased bladder urgency in cystitis
-Toxicity: increased body temp (due to decreased sweating), rapid pulse, dry mouth, dry
and flushed skin, cycloplegia, constipation, disorientation;
-Can cause acute angle-closure glaucoma in elderly (due to mydriasis), urinary
retention in men with prostatic hyperplasia, and hyperthermia in infants
-See also homatropine and tropicamide
Benztropine - correctanswer-Muscarinic antagonist
-Works in CNS
-Used in Parkinson disease and acute dystonia
Glycopyrrolate - correctanswer-Muscarinic antagonist
-Parental use: preoperative use to reduce airway secretions
-Oral use: drooling, peptic ulcer
Hyoscyamine - correctanswer-Muscarinic antagonist
-Antispasmodics for IBS
Dicyclomide - correctanswer-Muscarinic antagonist
-Antispasmodics for IBS
Ipratropium - correctanswer-Muscarinic antagonist
-Used in COPD and asthma
Tiotropium - correctanswer-Muscarinic antagonist
-Used in COPD and asthma
Oxybutynin - correctanswer-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Solifenacin - correctanswer-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
, Tolterodine - correctanswer-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Scopalamine - correctanswer-Muscarinic antagonist
-Motion sickness
Tetrodotoxin - correctanswer-Poisoning can result from ingestion of poorly prepared
puffer fish (exotic sushi)
-Highly potent toxin that binds fast voltage-gated Na+ channels in cardiac and nerve
tissue, preventing depolarization - blocks action potential without changing resting
potential (same mechanism as Lidocaine)
-Causes nausea, diarrhea, paresthesias, weakness, dizziness, loss of reflexes.
-Treatment is primarily supportive.
Ciguatoxin - correctanswer-Consumption of reef fish (e.g. barracuda, snapper, eel...)
-Causes ciguatera fish poisoning.
-Opens Na+ channels causing depolarization. Symptoms easily confused with
cholinergic poisoning.
-Temperature-related dysesthesia (e.g., "cold feels hot; hot feels cold") is regarded as a
specific finding of ciguatera.
-Treatment is primarily supportive.
Scombroid poisoning - correctanswer-Caused by consumption of dark-meat fish (e.g.,
bonito, mackerel, mahi-mahi, tuna) improperly stored at warm temperature.
-Bacterial histidine decarboxylase converts histidine to histamine. Histamine is not
degraded by cooking.
-Acute-onset burning sensation of the mouth, flushing of face, erythema, urticaria,
pruritus, headache. May cause anaphylaxis-like presentation (i.e., bronchospasm,
angioedema, hypotension).
-Frequently misdiagnosed as allergy to fish.
-Treat supportively with antihistamines; if needed, antianaphylactics (e.g.,
bronchodilators, epinephrine).
Albuterol - correctanswer-β2 > β1 direct agonist
-Acute asthma
Salmterol - correctanswer-β2 > β1 direct agonist
-Long term asthma or COPD control
Dobutamine - correctanswer-β1 > β2, α direct agonist
-Uses: heart failure (HF) (inotropic > chronotropic), cardiac stress testing.
Dopamine - correctanswer-D1 = D2 > β > α direct agonist
-Uses: unstable bradycardia, HF, shock; inotropic and chronotropic α effects
predominate at high doses.
What are the major functions of the α1 receptor? - correctanswerIncrease vascular
smooth muscle contraction, increase pupillary dilator muscle contraction (mydriasis),
increase intestinal and bladder sphincter muscle contraction
What are the major functions of the α2 receptor? - correctanswerDecrease sympathetic
outflow, decrease insulin release, decrease lipolysis, increase platelet aggregation,
decrease aqueous humor production
What are the major functions of the β1 receptor? - correctanswerIncrease heart rate,
increase contractility, increase renin release, increase lipolysis
What are the major functions of the β2 receptor? - correctanswerVasodilation,
bronchodilation, increase lipolysis, increase insulin release, decrease uterine tone
(tocolysis), ciliary muscle relaxation, increase aqueous humor production
What are the major functions of the M1 receptor? - correctanswerCNS, enteric nervous
system
What are the major functions of the M2 receptor? - correctanswerDecrease heart rate
and contractility of atria
What are the major functions of the M3 receptor? - correctanswerIncrease exocrine
gland secretions (e.g., lacrimal, salivary, gastric acid), increase gut peristalsis, increase
bladder contraction, increase bronchoconstriction, pupillary sphincter muscle
contraction (miosis), ciliary muscle contraction (accommodation)
What are the major functions of the D1 receptor? - correctanswerRelaxes renal vascular
smooth muscle
What are the major functions of the D2 receptor? - correctanswerModulates transmitter
release, especially in the brain
What are the major functions of the H1 receptor? - correctanswerIncrease nasal and
bronchial mucus production, increase vascular permeability, contraction of bronchioles,
pruritis, pain
What are the major functions of the H2 receptor? - correctanswerIncrease gastric acid
secretion
What are the major functions of the V1 receptor? - correctanswerIncrease vascular
smooth muscle contraction
,What are the major functions of the V2 receptor? - correctanswerIncrease H2O
permeability and reabsorption in collecting tubules of kidney (V2 is found in the "2"
kidneys)
What receptors are associate with Gq? - correctanswerH1, α1, V1, M1, and M3
What receptors are associated with Gs? - correctanswerH2, B1, B2, V2, D1
What receptors are associated with Gi? - correctanswerM2, α2, D2
Bethanechol - correctanswer-Direct cholinergic agonist
-Activates bowel and bladder smooth muscle
-Used in postoperative and neurogenic ileus
-Resistant to AChE
Carbachol - correctanswer-Direct cholinergic agonist
-Carbon copy of acetylcholine
-Constricts pupils and relieves intraocular pressure in glaucoma
Methacholine - correctanswer-Direct cholinergic agonist
-Stimulates muscarinic receptors in airways when inhaled
-Used as a challenge test for diagnosis of asthma
Pilocarpine - correctanswer-Direct cholinergic agonist
-Contracts ciliary muscle of eye (open angle glaucoma), contracts pupillary sphincter
(closed angle glaucoma)
-Potent stimulator of sweat, tears and saliva
-AChE resistant
Donepezil - correctanswer-Anticholinesterse - increases ACh
-Alzheimer disease
Galantamine - correctanswer-Anticholinesterse - increases ACh
-Alzheimer disease
Rivastigmine - correctanswer-Anticholinesterse - increases ACh
-Alzheimer disease
Edrophonium - correctanswer-Anticholinesterse - increases ACh
-Historically used to diagnose myasthenia gravis (MG is now diagnosed by anti-AChR
Ab test.
Neostigmine - correctanswer-Anticholinesterse - increases ACh
-Used in postoperative and neurogenic ileus and urinary retention, myasthenia gravis,
and postoperative reversal of neuromuscular junction blockade
,Physostigmine - correctanswer-Anticholinesterse - increases ACh
-Used in anticholinergic toxicity
-Crosses the blood-brain barrier (CNS)
Pyridostigmine - correctanswer-Anticholinesterse - increases ACh
-Increases muscle strength
-Used in myasthenia gravis (long acting)
-Does not penetrate CNS
Atropine - correctanswer-Muscarinic antagonist
-Used in bradycardia and for ophthalmic applications
-Also used as antidote for cholinesterase inhibitor poisoning
-Actions include increase pupil dilation, cycloplegia, decreased airway secretions,
decreased acid secretions, decreased gut motility, decreased bladder urgency in cystitis
-Toxicity: increased body temp (due to decreased sweating), rapid pulse, dry mouth, dry
and flushed skin, cycloplegia, constipation, disorientation;
-Can cause acute angle-closure glaucoma in elderly (due to mydriasis), urinary
retention in men with prostatic hyperplasia, and hyperthermia in infants
-See also homatropine and tropicamide
Benztropine - correctanswer-Muscarinic antagonist
-Works in CNS
-Used in Parkinson disease and acute dystonia
Glycopyrrolate - correctanswer-Muscarinic antagonist
-Parental use: preoperative use to reduce airway secretions
-Oral use: drooling, peptic ulcer
Hyoscyamine - correctanswer-Muscarinic antagonist
-Antispasmodics for IBS
Dicyclomide - correctanswer-Muscarinic antagonist
-Antispasmodics for IBS
Ipratropium - correctanswer-Muscarinic antagonist
-Used in COPD and asthma
Tiotropium - correctanswer-Muscarinic antagonist
-Used in COPD and asthma
Oxybutynin - correctanswer-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Solifenacin - correctanswer-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
, Tolterodine - correctanswer-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Scopalamine - correctanswer-Muscarinic antagonist
-Motion sickness
Tetrodotoxin - correctanswer-Poisoning can result from ingestion of poorly prepared
puffer fish (exotic sushi)
-Highly potent toxin that binds fast voltage-gated Na+ channels in cardiac and nerve
tissue, preventing depolarization - blocks action potential without changing resting
potential (same mechanism as Lidocaine)
-Causes nausea, diarrhea, paresthesias, weakness, dizziness, loss of reflexes.
-Treatment is primarily supportive.
Ciguatoxin - correctanswer-Consumption of reef fish (e.g. barracuda, snapper, eel...)
-Causes ciguatera fish poisoning.
-Opens Na+ channels causing depolarization. Symptoms easily confused with
cholinergic poisoning.
-Temperature-related dysesthesia (e.g., "cold feels hot; hot feels cold") is regarded as a
specific finding of ciguatera.
-Treatment is primarily supportive.
Scombroid poisoning - correctanswer-Caused by consumption of dark-meat fish (e.g.,
bonito, mackerel, mahi-mahi, tuna) improperly stored at warm temperature.
-Bacterial histidine decarboxylase converts histidine to histamine. Histamine is not
degraded by cooking.
-Acute-onset burning sensation of the mouth, flushing of face, erythema, urticaria,
pruritus, headache. May cause anaphylaxis-like presentation (i.e., bronchospasm,
angioedema, hypotension).
-Frequently misdiagnosed as allergy to fish.
-Treat supportively with antihistamines; if needed, antianaphylactics (e.g.,
bronchodilators, epinephrine).
Albuterol - correctanswer-β2 > β1 direct agonist
-Acute asthma
Salmterol - correctanswer-β2 > β1 direct agonist
-Long term asthma or COPD control
Dobutamine - correctanswer-β1 > β2, α direct agonist
-Uses: heart failure (HF) (inotropic > chronotropic), cardiac stress testing.
Dopamine - correctanswer-D1 = D2 > β > α direct agonist
-Uses: unstable bradycardia, HF, shock; inotropic and chronotropic α effects
predominate at high doses.
