The big review Flashcards
A
- Lambert-Eaton Myasthenic Syndrome is caused by antibodies to pre-synaptic Ca2+ channels, which reduces acetylcholine release during action potentials*
- the mepp stays normal because each vesicle has a normal amount of ACh, the response to ACh is normal because the post-synaptic receptors are normal, but the epp amplitude is reduced because fewer ACh vesicles are released from the nerve terminal in each AP*
A severely depressed 45-year-old woman is unresponsive to antidepressant medications and is being prepared to undergo electroconvulsive shock therapy. The neuromuscular blocker of choice for this procedure is succinylcholine. Unfortunately the patient also has an undiagnosed pseudocholinesterase deficiency and the skeletal neuromuscular blockade becomes extremely long-lasting. Muscle tension measurements reveal that block was originally Phase I (block by depolarization) but proceeded to Phase 2 (block by desensitization). Phase 2 block most likely has which one of the following characteristics?
A. The end-plate is persistently depolarized.
B. The conduction of action potentials in motor nerve endings is impaired.
C. Transmission can be restored with exogenous acetylcholine.
D. No decrement in the muscle twitch is observed with repetitive stimulation
E. The electrical excitability of the muscle at the end-plate region is normal.
E. The electrical excitability of the muscle at the end-plate region is normal.
- phase 2 depolarizing block is when the membrane repolarizes to baseline levels but remains hyposensitive to neurotransmitters*
- can occur with prolonged treatment with depolarizing blockers (succinylcholine) but not with non-depolarizing blockers (ex. -curoniums)*
A 17-year-old woman underwent a 40 minute abdominal surgical procedure. The anesthesiologist used a combination of succinylcholine and vecuronium to produce neuromuscular blockade. Which one of the following statements represents the appropriate use and assessment of these blocking drugs?
A) Succinylcholine can be used for the duration of this surgical procedure.
B) The depth of neuromuscular block during surgery should show complete elimination of all twitches during train-of-four stimulation.
C) Reversal of neuromuscular block should show twitches to all four stimuli in the train of four paradigm.
D) Intubation should be accomplished with vecuronium followed by succinylcholine
E) Recovery is considered complete when the ratio of the fourth to the first twitch is 70%.
C) Reversal of neuromuscular block should show twitches to all four stimuli in the train of four paradigm.
- succinylcholine should be used only for intubation at the beginning*
- there does not need to be elimination of all four twitches, just 2 or 3 depending on the drug*
- ALL four twitches must be back to demonstrate complete reversal*
A 23-year-old woman is a Marine serving in Afghanistan. She is discovered in extreme distress suffering from the symptoms of sarin poisoning. Which one of the following is the most likely description of her symptoms?
A. Urinary retention, increased salivary secretion, involuntary defecation.
B. Bronchodilation, cycloplegia, excessive urination, constipation.
C. Pupillary dilation, cyclospasm, tachycardia, increased force of voluntary muscle contractions.
D. Decreased sweating, urinary retention, abdominal cramps, bradycardia
E. Miotic pupils, runny nose, excessive sweating, involuntary micturition and defecation
E. Miotic pupils, runny nose, excessive sweating, involuntary micturition and defecation
poisoning with irreversible cholinesterase inhibitors leads to SLUDD syndrome: Salivation, lacrimation, urination, defecation, and digestion. It can also include mitotic pupils.
Very early in the morning on November 3rd, 2016, a highly obtunded, 24-year-old-male was found wearing Chicago Cubs paraphernalia sitting next to his van staring into space near Wrigley Field. When paramedics arrived, he was heard repeatedly muttering repeatedly: “Finally, 108 years, 108 years, Oh My God, 108 years, Byrzzo for MVP, 108 years”. En route to the hospital, IV thiamine, glucose and naloxone (an opioid antagonist) were administered by paramedics without improvement of his condition. His face was red and flushed. Ophthalmological examination showed 7.5-mm-diameter pupils (2-3mm is normal). There was no ptosis. His body temperature was 38.9oC (102oF). He was unable to urinate and insertion of a Foley catheter revealed 500 mL of urine. Which of the following is the most likely cause of this patient’s condition?
A. Myasthenia gravis
B. Organophosphorus anticholinesterase poisoning
C. Muscarine poisoning from ingesting mushrooms.
D. Atropine poisoning
E. Botulism
D. Atropine poisoning
atropine poisoning: “blind as a bat, red as a beet, hot as a hare, mad as a hatter, dry as a bone”
An 81-year-old man who is a resident of a skilled nursing facility is being treated for urinary incontinence with bladder training and the use of absorbent pads. Fesoterodine is prescribed to treat the instability of the patient’s detrusor muscle. The patient is at increased risk for which one of the following adverse effects?
A. Pupillary miosis
B. Diarrhea
C. Dry mouth
D. Excessive secretion from lacrimal glands
E. Ciliary muscle spasm
C. Dry mouth
- fesoterodine is a muscarinic antagonist, so it can help with contstriction of the ureter and relaxation of the bladder walls but it also has side effects related to inhibition of parasympathetic activity*
- dry mouth is a symptom of lack of lacrimal secretion, which occurs as a result of dampened parasympathetic responses*
A 45-year-old woman is brought to the emergency department because of a 7-hour history of severe eye pain. She said that she fell asleep while wearing her contact lenses. Ophthalmological examination shows abrasions on both corneas and you suspect that ciliary muscle spasms are responsible for the patient’s eye pain. Which of the following is the most appropriate pharmacotherapy to alleviate the patient’s pain?
A. Neostigmine
B. Pilocarpine
C. Phenylephrine
D. Homatropine
E. Amphetamine
D. Homatropine
- homatropine is a muscarinic antagonist that can reduce ciliary muscle spasm*
- neostigmine = anti-cholinesterase*
- pilocarpine = muscarinic receptor agonist*
- phenylephrine = alpha 1 agonist*
- amphetamine = elevates concentration of NE*
A 69-year-old man faints while on stage at a university function. Prior to fainting, he complained of fatigue, dizziness and labored breathing. His blood pressure was 80/60 mm Hg, heart rate=45/min. The ECG reveals a normal QRS complex but the PR interval is increased. Lung exam demonstrates wheezing. He was started on a new drug for hypertension 4 days ago and laboratory analysis revealed that the plasma levels of this drug were elevated beyond the desirable level. Based upon this history, which one of the following is the most likely pairing of antihypertensive agent and cytochrome P450 (CYP) polymorphism responsible for his symptoms?
A. Clonidine-CYP2D6
B. Clonidine-CYP3A4
C. Propranolol-CYP2D6
D. Propranolol-CYP3A4
E. Albuterol-CYP2D6
C. Propranolol-CYP2D6
- propranolol is a beta1 and beta2 blocker, which explains his “wheezing” on exam (beta2 blockade leads to bronchoconstriction)*
- propranolol is also metabolized with CYP2D6*
- clonidine is selective for alpha receptors of the CNS and is not used for hypertension*
- albuterol is a beta2 agonist and would lead to bronchodilation*
A 72-year-old woman with pure autonomic failure (a disease associated with defective baroreflexes) is being treated with midodrine for postural hypotension. Which one of the following is most likely to result from an injection of midodrine in this patient?
A. A decrease in total peripheral resistance (tpr) and an increase in heart rate (hr)
B. An increase in tpr and an increase in hr
C. An increase in tpr and no change in hr
D. A decrease in tpr and an increase in systolic blood pressure
E. A decrease in tpr and a decrease in systolic blood pressure
C. An increase in tpr and no change in hr
midodrine is a selective alpha1 receptor agonist, which leads to vasoconstriction and increased TPR without changing the heart rate
A 28-year-old man is recovering from abdominal surgery. Rocuronium was used to reduce skeletal muscle tone during the surgery and the anesthesiologist wishes to rapidly reverse the effects of blocking drug with an agent that does not affect autonomic nervous system function. Which of the following drugs was the most likely to be used to reverse rocuronium block?
- Neostigmine
- Edrophonium
- Sugammadex
- Succinylcholine
- Ephedrine
A. Sugammadex
- sugammadex reverses blockade by -curonium drugs*
- neostigmine and edrophonium are anti-cholinesterases, succinylcholine is a depolarizing blocker, ephedrine is a sympathomimetic*
A 58-year-old woman undergoes a retinal examination. The intraocular pressure in the right eye is 24 mmHg and 19 mmHg in the left eye. The patient has hazel eyes. The ophthalmologist prescribes a drug that increases the outflow of aqueous humor to be used in the right eye alone. The patient begins to notice a gradual change in her eye color from hazel to dark brown in the effected eye as well as a darkening of the eyelid. Which one of the following drugs was most likely to have been prescribed?
A. Timolol
B. Phenylephrine
C. Latanoprost
D. Pilocarpine
E. Brimonidine
C. Latanoprost
- latanoprost increases outflow of aqueous humor, but has a side effect of changing eye and eyelid color*
- timolol is a beta blocker that reduces formation of aqueous humor but does not have these side effects*
- phenylephrine is an alpha1 agonist used as a nasal decongestant*
- pilocarpine is a muscarinic agonist that causes pupil constriction*
- brimonidine is an alpha2 agonist that reduces aqueous humor production*
An 81-year-old man being treated with terazosin for benign prostatic hypertrophy (BPH) complains to his physician that he gets very dizzy upon standing up. Monitoring of the patient’s blood pressure revealed a sustained fall in blood pressure upon standing. Given these symptoms, which one of the following drugs is the most appropriate drug to substitute for terazosin to treat the patient’s BPH and alleviate the orthostatic hypotension this patient experiences?
A. Terazosin
B. Silodosin
C. Doxazosin
D. Prazosin
E. Phentolamine
B. Silodosin
- silodosin is highly uroselective antagonist for alpha 1A and does not have the other alpha 1 effects (like hypotension)*
- -zosin drugs all have hypotensive side effects*
- phentolamine is not selective for alpha1 over alpha2*
A 40-year-old man comes to the physician because of a 2-month history of decreased libido associated with erectile dysfunction (ED). He has a major depressive disorder treated with a selective serotonin reuptake inhibitor for the past 10 weeks. He reports that his depressive symptoms have improved. You add an oral drug to treat his ED. Which of the following is the most likely mechanism of action of the drug used to treat ED in this patient?
A. Increased release of nitric oxide from parasympathetic nerve endings.
B. Increased cAMP degradation in the corpus cavernosum
C. Inhibition of nitric oxide synthase
D. Inhibition of cGMP degradation in the corpus cavernosum
E. Deceased cAMP synthesis in cavernosal nerve endings
D. Inhibition of cGMP degradation in the corpus cavernosum
nerve signaling in the corpus cavernosum causes erections, so inhibition of cGMP degradation will prolong nerve activation
A 29-year-old-woman reports to her physician with symptoms of chronic dry eyes and dry mouth. She is diagnosed with Primary Sjogren’s Syndrome. The physician prescribes a drug that has the highest efficacy in treating these symptoms. Which one of the following agents is the most likely to be prescribed?
A. Pilocarpine
B. Atropine
C. Cevimiline
D. Tolterodine
E. Neostigmine
C. Cevimiline
cevimiline is a muscarinic agonist that can increase secretions (lack of secretions is a key problem in Sjogren’s)
A 57-year-old man returns to his urologist after beings treated for 3 weeks with a muscarinic receptors antagonist for overactive bladder. The patient complains that the drug had no effect to alleviate his symptoms of urinary urgency, frequency and leakage. The urologist advises the patient to stop taking the drug and instead prescribes a different drug that acts as an agonist on beta-3 receptors. Which one of the following agents was the new drug prescribed?
A. Toterodine
B. Mirabegron
C. Darifenacin
D. Tropicamide
D. Bethanechol
B. Mirabegron
- mirabegron is a beta3 agonist, which is selective for the bladder*
- toterodine, darifenacin, and tropicamide are muscarinic antagonists, bethanechol is a parasympathomimetic*
A. alpha-adrenoreceptors are desensitized
B. beta-adrenoreceptors are desensitized
C. muscarinic receptors are downregulated
D. the central nervous system input to the pupil is damaged
E. Sympathetic nerves have been severed
E. Sympathetic nerves have been severed
the left pupil is still able to be dilated through direct activation of the adrenoreceptors on the eye when epinephrine is administered, but when tyramine is added (which leads to increased release of norepinephrine) there is no effect which indicates that the sympathetic pathway is disrupted somewhere upstream of the eye
A. Prazosin
- this experiment shows epinephrine reversal, which occurs when epinephrine is administered with an alpha selective blocker, which allows the beta effects of epinephrine to dominate (leading to decreased TPR)*
- prazosin is the only alpha selective blocker listed*
A. Drug A is norepinephrine; drug B is epinephrine
B. Drug A is norepinephrine; drug B is isoproterenol
C. Drug A is epinephrine; drug B is isoproterenol
D. Drug A is epinephrine; drug B is norepinephrine
E. Drug A is isoproterenol; drug B is epinephrine
B. Drug A is norepinephrine; drug B is isoproterenol
- norepinephrine favors alpha receptors, which vasoconstrict and have slight reflex bradycardia*
- isoproterenol favors beta receptors, which vasodilate and increase heart rate/contractility*
- epinephrine’s effects are dose dependent –> low doses = decreased TPR, high doses = initial increase in TPR (why epi is used as a pressor)*
