Pharmacology USMLE step 1 Exam NEW UPDATE 2023 WITH QUESTIONS AND CORRECT ANSWERS |GRADED A What are the major functions of the α1 receptor? - ANSWER - Increase vascular smooth muscle contraction, increase pupillary dilator muscle contraction (mydriasis), increase intestin al and bladder sphincter muscle contraction What are the major functions of the α2 receptor? - ANSWER - Decrease sympathetic outflow, decrease insulin release, decrease lipolysis, increase platelet aggregation, decrease aqueous humor production What are t he major functions of the β1 receptor? - ANSWER - Increase heart rate, increase contractility, increase renin release, increase lipolysis What are the major functions of the β2 receptor? - ANSWER - Vasodilation, 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? - ANSWER - CNS, enteric nervous system What are the major functions of the M2 receptor? - ANSWER - Decrease heart rate and contractility of atria What are the major functions of the M3 receptor? - ANSWER - Increase exocrine gland secretions (e.g., lacrimal, salivary, gastric acid), increase gut peristalsis, increase bladder contraction, increase b ronchoconstriction, pupillary sphincter muscle contraction (miosis), ciliary muscle contraction (accommodation) What are the major functions of the D1 receptor? - ANSWER - Relaxes renal vascular smooth muscle What are the major functions of the D2 receptor? - ANSWER - Modulates transmitter release, especially in the brain What are the major functions of the H1 receptor? - ANSWER - Increase nasal and bronchial mucus production, increase vascular permeability, con traction of bronchioles, pruritis, pain What are the major functions of the H2 receptor? - ANSWER - Increase gastric acid secretion What are the major functions of the V1 receptor? - ANSWER - Increase vascular smooth muscle contraction What are the major functions of the V2 receptor? - ANSWER - Increase H2O permeability and reabsorption in collecting tubules of kidney (V2 is found in the "2" kidneys) What receptors are associate with Gq? - ANSWER - H1, α1, V1, M1, and M3 What receptors are associated with Gs? - ANSWER - H2, B1, B2, V2, D1 What receptors are associated with Gi? - ANSWER - M2, α2, D2 Bethanechol - ANSWER - -Direct cholinergic agonist -Activates bowel and bladder smooth muscle -Used in postoperative and neurogenic ileus -Resistant to AChE Carbachol - ANSWER - -Direct cholinergic agonist -Carbon copy of acetylcholine -Constricts pupils and relieves intraocular pressure in glaucoma Methacholine - ANSWER - -Direct cholinergic agonist -Stimulates muscarinic receptors in airways when inhaled -Used as a challenge test for diagnosis of asthma Pilocarpine - ANSWER - -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 - ANSWER - -Anticholinesterse - increases ACh -Alzheimer disease Galantamine - ANSWER - -Anticholinesterse - increases ACh -Alzheimer disease Rivastigmine - ANSWER - -Anticholinesterse - increases ACh -Alzheimer disease Edrophon ium - ANSWER - -Anticholinesterse - increases ACh -Historically used to diagnose myasthenia gravis (MG is now diagnosed by anti -AChR Ab test. Neostigmine - ANSWER - -Anticholinesterse - increases ACh -Used in postoperative and neurogenic ileus and urinary r etention, myasthenia gravis, and postoperative reversal of neuromuscular junction blockade Physostigmine - ANSWER - -Anticholinesterse - increases ACh -Used in anticholinergic toxicity -Crosses the blood -brain barrier (CNS) Pyridostigmine - ANSWER - -Antic holinesterse - increases ACh -Increases muscle strength -Used in myasthenia gravis (long acting) -Does not penetrate CNS Atropine - ANSWER - -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, an d hyperthermia in infants -See also homatropine and tropicamide Benztropine - ANSWER - -Muscarinic antagonist -Works in CNS -Used in Parkinson disease and acute dystonia Glycopyrrolate - ANSWER - -Muscarinic antagonist -Parental use: preoperative use to r educe airway secretions -Oral use: drooling, peptic ulcer Hyoscyamine - ANSWER - -Muscarinic antagonist -Antispasmodics for IBS Dicyclomide - ANSWER - -Muscarinic antagonist -Antispasmodics for IBS Ipratropium - ANSWER - -Muscarinic antagonist -Used in COP D and asthma Tiotropium - ANSWER - -Muscarinic antagonist -Used in COPD and asthma Oxybutynin - ANSWER - -Muscarinic antagonist -Reduced bladder spasms and urge urinary incontinence Solifenacin - ANSWER - -Muscarinic antagonist -Reduced bladder spasms and urge urinary incontinence Tolterodine - ANSWER - -Muscarinic antagonist -Reduced bladder spasms and urge urinary incontinence Scopalamine - ANSWER - -Muscarinic antagonist -Motion sickness Tetrodotoxin - ANSWER - -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 me chanism as Lidocaine) -Causes nausea, diarrhea, paresthesias, weakness, dizziness, loss of reflexes. -Treatment is primarily supportive. Ciguatoxin - ANSWER - -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 - ANSWER - -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 - ANSWER - -β2 > β1 direct agonist -Acute asthma Salmterol - ANSWER - -β2 > β1 direct agonist -Long term asthma or COPD control Dobutami ne - ANSWER - -β1 > β2, α direct agonist -Uses: heart failure (HF) (inotropic > chronotropic), cardiac stress testing. Dopamine - ANSWER - -D1 = D2 > β > α direct agonist
