USMLE STEP 1 PHARMACOLOGY
2026/2027 WITH 870 QUESTIONS AND
CORRECT ANSWERS RATED A+
Pilocarpine
-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
-Anticholinesterse - increases ACh
-Alzheimer disease
Galantamine
-Anticholinesterse - increases ACh
-Alzheimer disease
Rivastigmine
-Anticholinesterse - increases ACh
-Alzheimer disease
Edrophonium
-Anticholinesterse - increases ACh
-Historically used to diagnose myasthenia gravis (MG is now diagnosed by anti-
AChR Ab test.
Neostigmine
,-Anticholinesterse - increases ACh
-Used in postoperative and neurogenic ileus and urinary retention, myasthenia
gravis, and postoperative reversal of neuromuscular junction blockade
Physostigmine
-Anticholinesterse - increases ACh
-Used in anticholinergic toxicity
-Crosses the blood-brain barrier (CNS)
Pyridostigmine
-Anticholinesterse - increases ACh
-Increases muscle strength
-Used in myasthenia gravis (long acting)
-Does not penetrate CNS
Atropine
-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
-Muscarinic antagonist
-Works in CNS
-Used in Parkinson disease and acute dystonia
Glycopyrrolate
,-Muscarinic antagonist
-Parental use: preoperative use to reduce airway secretions
-Oral use: drooling, peptic ulcer
Hyoscyamine
-Muscarinic antagonist
-Antispasmodics for IBS
Dicyclomide
-Muscarinic antagonist
-Antispasmodics for IBS
Ipratropium
-Muscarinic antagonist
-Used in COPD and asthma
Tiotropium
-Muscarinic antagonist
-Used in COPD and asthma
Oxybutynin
-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Solifenacin
-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Tolterodine
-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Scopalamine
-Muscarinic antagonist
-Motion sickness
, Tetrodotoxin
-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
-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
-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
-β2 > β1 direct agonist
-Acute asthma
Salmterol
2026/2027 WITH 870 QUESTIONS AND
CORRECT ANSWERS RATED A+
Pilocarpine
-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
-Anticholinesterse - increases ACh
-Alzheimer disease
Galantamine
-Anticholinesterse - increases ACh
-Alzheimer disease
Rivastigmine
-Anticholinesterse - increases ACh
-Alzheimer disease
Edrophonium
-Anticholinesterse - increases ACh
-Historically used to diagnose myasthenia gravis (MG is now diagnosed by anti-
AChR Ab test.
Neostigmine
,-Anticholinesterse - increases ACh
-Used in postoperative and neurogenic ileus and urinary retention, myasthenia
gravis, and postoperative reversal of neuromuscular junction blockade
Physostigmine
-Anticholinesterse - increases ACh
-Used in anticholinergic toxicity
-Crosses the blood-brain barrier (CNS)
Pyridostigmine
-Anticholinesterse - increases ACh
-Increases muscle strength
-Used in myasthenia gravis (long acting)
-Does not penetrate CNS
Atropine
-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
-Muscarinic antagonist
-Works in CNS
-Used in Parkinson disease and acute dystonia
Glycopyrrolate
,-Muscarinic antagonist
-Parental use: preoperative use to reduce airway secretions
-Oral use: drooling, peptic ulcer
Hyoscyamine
-Muscarinic antagonist
-Antispasmodics for IBS
Dicyclomide
-Muscarinic antagonist
-Antispasmodics for IBS
Ipratropium
-Muscarinic antagonist
-Used in COPD and asthma
Tiotropium
-Muscarinic antagonist
-Used in COPD and asthma
Oxybutynin
-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Solifenacin
-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Tolterodine
-Muscarinic antagonist
-Reduced bladder spasms and urge urinary incontinence
Scopalamine
-Muscarinic antagonist
-Motion sickness
, Tetrodotoxin
-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
-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
-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
-β2 > β1 direct agonist
-Acute asthma
Salmterol
