A 33-year-old woman comes to the physician because of a 3-day history of dry cough and low-grade fever. Four months ago, she was diagnosed with major depressive disorder and started treatment with fluoxetine. Physical examination shows no abnormalities. A diagnosis of upper respiratory infection is made and medication is prescribed to relieve her symptoms. A drug with which of the following mechanisms of action should be avoided in this patient?
Q652
A 64-year-old man presents to his physician for a scheduled follow-up visit. He has chronic left-sided heart failure with systolic dysfunction. His current regular medications include captopril and digoxin, which were started after his last episode of symptomatic heart failure approximately 3 months ago. His last episode of heart failure was accompanied by atrial fibrillation, which followed an alcohol binge over a weekend. Since then he stopped drinking. He reports that he has no current symptoms at rest and is able to perform regular physical exercise without limitation. On physical examination, mild bipedal edema is noted. The physician suggested to him that he should discontinue digoxin and continue captopril and scheduled him for the next follow-up visit. Which of the following statements best justifies the suggestion made by the physician?
Q653
A 19-year-old G1P0 presents to the emergency department with severe abdominal pain. She states that the pain has been recurring every 3 to 5 minutes for the past 5 hours. She denies having regular prenatal care but recalls that her last menstrual period was about 9 months ago. She initially denies substance use but later admits to occasional prescription pain medication use during pregnancy. Her temperature is 98°F (37°C), blood pressure is 120/60 mmHg, pulse is 120/min, and respirations are 18/min. Tenderness is elicited in the lower abdominal quadrants. Clear fluid is seen in her vaginal vault with a fetal crown seen at 10 cm cervical dilation and +1 station. The patient is emergently taken into the labor and delivery suite, where she delivers a male infant with APGAR scores of 9 and 9 at 5 and 10 minutes, respectively. Several hours after delivery, the nurse notes that the infant is very irritable and crying in high pitches. The infant appears very diaphoretic with a runny nose and flailing limbs. What is the necessary pharmacological treatment for this patient?
Q654
A 25-year-old woman presents to the ED with nausea, vomiting, diarrhea, abdominal pain, and hematemesis after ingesting large quantities of a drug. Which of the following pairs a drug overdose with the correct antidote for this scenario?
Q655
A 48-year-old woman comes to the physician for a follow-up examination. At her visit 1 month ago, her glomerular filtration rate (GFR) was 100 mL/min/1.73 m2 and her renal plasma flow (RPF) was 588 mL/min. Today, her RPF is 540 mL/min and her filtration fraction (FF) is 0.2. After her previous appointment, this patient was most likely started on a drug that has which of the following effects?
Q656
A 17-year-old man presents to his primary care physician with bilateral tremor of the hands. He is a senior in high school and during the year, his grades have plummeted to the point that he is failing. He says his memory is now poor, and he has trouble focusing on tasks. His behavior has changed in the past 6 months in that he has frequent episodes of depression, separated by episodes of bizarre behavior, including excessive alcohol drinking and shoplifting. His parents have started to suspect that he is using street drugs, which he denies. His handwriting has become very sloppy. His parents have noted slight slurring of his speech. Family history is irrelevant. Physical examination reveals upper extremity tremors, mild dystonia of the upper extremities, and mild incoordination involving his hands. The patient’s eye is shown. Which of the following is the best initial management of this patient’s condition?
Q657
A 23-year-old male is brought into the emergency department by his girlfriend following an argument. The patient’s girlfriend claims that she threatened to break up with him. He then called her saying he was going to kill himself. When she arrived at the patient’s home, she found him lying on the couch with empty alcohol bottles and multiple pill containers. The patient reports he does not remember everything he took, but says he ingested many pills about four hours ago. The patient’s temperature is 99°F (37.2°C), blood pressure is 110/68 mmHg, pulse is 88/min, and respirations are 25/min with an oxygen saturation of 98% O2 on room air. An arterial blood gas (ABG) is obtained, with results shown below:
pH: 7.47
pO2: 94 mmHg
pCO2: 24 mmHg
HCO3-: 22 mEq/L
You check on him a couple hours later, and the patient appears agitated. His girlfriend says he keeps grabbing his head, yelling about non-stop ringing in his ears. Labs and a repeat ABG shows:
pH: 7.30
pO2: 90 mmHg
pCO2: 22 mmHg
HCO3-: 9 mEq/L
Na+: 144 mEq/L
Cl-: 98 mEq/L
K+: 3.6 mEq/L
BUN: 18 mg/dL
Glucose: 100 mg/dL
Creatinine: 1.4 mg/dL
Which of the following is the best next step in management?
Q658
A 45-year-old woman comes to the physician because of a 6-month history of worsening involuntary movement of the left hand. Her symptoms are worse when she feels stressed at work. She has no history of serious illness and takes no medications. Neurological examination shows difficulty initiating movement and a tremor in the left hand at rest. The tremor decreases when the patient is asked to draw a circle. Which of the following is the most appropriate pharmacotherapy?
Q659
A previously healthy 29-year-old man comes to the emergency department because of a 4-day history of abdominal pain and confusion. Prior to the onset of the abdominal pain, he visited a festival where he consumed large amounts of alcohol. Examination shows a distended abdomen, decreased bowel sounds, and diffuse tenderness to palpation. There is motor weakness in the upper extremities. Sensation is decreased over the upper and lower extremities. Laboratory studies show no abnormalities. Which of the following is the most appropriate therapy for this patient's condition?
Q660
A 45-year-old male presents to the emergency room for toe pain. He reports that his right great toe became acutely painful, red, and swollen approximately five hours prior. He has had one similar prior episode six months ago that resolved with indomethacin. His medical history is notable for obesity, hypertension, and alcohol abuse. He currently takes hydrochlorothiazide (HCTZ). On physical examination, his right great toe is swollen, erythematous, and exquisitely tender to light touch. The patient is started on a new medication that decreases leukocyte migration and mitosis, and his pain eventually resolves; however, he develops nausea and vomiting as a result of therapy. Which of the following underlying mechanisms of action is characteristic of this patient’s new medication?
Autonomic/CV Drugs US Medical PG Practice Questions and MCQs
Question 651: A 33-year-old woman comes to the physician because of a 3-day history of dry cough and low-grade fever. Four months ago, she was diagnosed with major depressive disorder and started treatment with fluoxetine. Physical examination shows no abnormalities. A diagnosis of upper respiratory infection is made and medication is prescribed to relieve her symptoms. A drug with which of the following mechanisms of action should be avoided in this patient?
A. Inhibition of H1 receptors
B. Inhibition of NMDA glutamate receptors (Correct Answer)
C. Disruption of mucoid disulfide bonds
D. Inhibition of cyclooxygenase enzymes
E. Stimulation of α-adrenergic receptors
Explanation: ***Inhibition of NMDA glutamate receptors***
- This mechanism describes **dextromethorphan**, a commonly used antitussive (cough suppressant) for upper respiratory infections
- Dextromethorphan has **serotonergic activity** and can precipitate **serotonin syndrome** when combined with SSRIs like fluoxetine
- Serotonin syndrome presents with mental status changes, autonomic hyperactivity (hyperthermia, tachycardia, diaphoresis), and neuromuscular abnormalities (hyperreflexia, clonus, rigidity)
- This is a **well-documented drug interaction** that should be avoided; alternative antitussives like benzonatate or guaifenesin should be used instead
*Inhibition of H1 receptors*
- This mechanism describes **first-generation antihistamines** (e.g., diphenhydramine, chlorpheniramine) used for cough and congestion
- These are **generally safe** with fluoxetine, though may cause additive sedation
- Do not pose a risk for serotonin syndrome
*Disruption of mucoid disulfide bonds*
- This mechanism describes **mucolytics** like N-acetylcysteine, which break down mucus to facilitate expectoration
- No significant drug interaction with fluoxetine
- Safe to use concurrently
*Inhibition of cyclooxygenase enzymes*
- This mechanism describes **NSAIDs** (e.g., ibuprofen, naproxen) used for fever and body aches
- SSRIs can modestly increase risk of GI bleeding when combined with NSAIDs due to decreased platelet serotonin
- However, NSAIDs are **not contraindicated** for short-term symptomatic relief and do not cause serotonin syndrome
*Stimulation of α-adrenergic receptors*
- This mechanism describes **nasal decongestants** (e.g., pseudoephedrine, phenylephrine) used for nasal congestion
- Generally safe with SSRIs; no serotonin syndrome risk
- May cause mild elevation in blood pressure but this is typically not clinically significant
Question 652: A 64-year-old man presents to his physician for a scheduled follow-up visit. He has chronic left-sided heart failure with systolic dysfunction. His current regular medications include captopril and digoxin, which were started after his last episode of symptomatic heart failure approximately 3 months ago. His last episode of heart failure was accompanied by atrial fibrillation, which followed an alcohol binge over a weekend. Since then he stopped drinking. He reports that he has no current symptoms at rest and is able to perform regular physical exercise without limitation. On physical examination, mild bipedal edema is noted. The physician suggested to him that he should discontinue digoxin and continue captopril and scheduled him for the next follow-up visit. Which of the following statements best justifies the suggestion made by the physician?
A. Long-term digoxin therapy produces significant survival benefits in patients with heart failure, but at the cost of increased heart failure-related admissions.
B. Both captopril and digoxin are likely to improve the long-term survival of the patient with heart failure, but digoxin has more severe side effects.
C. Captopril is likely to improve the long-term survival of the patient with heart failure, unlike digoxin.
D. Digoxin does not benefit patients with left-sided heart failure in the absence of atrial fibrillation.
E. Digoxin is useful to treat atrial fibrillation, but does not benefit patients with systolic dysfunction who are in sinus rhythm. (Correct Answer)
Explanation: ***Digoxin is useful to treat atrial fibrillation, but does not benefit patients with systolic dysfunction who are in sinus rhythm.***
- The patient's **atrial fibrillation** was likely triggered by the alcohol binge and has since resolved, suggesting he is now in **sinus rhythm**.
- Digoxin's primary benefit in heart failure with **systolic dysfunction** (HFrEF) is to control ventricular rate in patients with **atrial fibrillation**, but it does not offer survival benefit in HFrEF patients who are in **sinus rhythm** and well-managed with other therapies.
*Long-term digoxin therapy produces significant survival benefits in patients with heart failure, but at the cost of increased heart failure-related admissions.*
- This statement is incorrect; digoxin has been shown to **reduce hospital admissions** for heart failure, but it does **not provide a significant survival benefit** in patients with HFrEF in sinus rhythm.
- The main benefit of digoxin in HFrEF is to improve symptoms and quality of life, alongside reducing hospitalizations, but not prolonging life.
*Both captopril and digoxin are likely to improve the long-term survival of the patient with heart failure, but digoxin has more severe side effects.*
- **Captopril (an ACE inhibitor)** does improve **long-term survival** in heart failure, but **digoxin does not** demonstrably improve survival.
- While digoxin can have side effects, its lack of survival benefit for HFrEF in sinus rhythm is the primary reason for discontinuation, not just side effect severity.
*Captopril is likely to improve the long-term survival of the patient with heart failure, unlike digoxin.*
- This statement is partially correct that **captopril improves survival**, but it does not fully explain the physician's decision to discontinue digoxin.
- The key missing piece is the patient's current **sinus rhythm** and the lack of benefit of digoxin in that specific context for HFrEF.
*Digoxin does not benefit patients with left-sided heart failure in the absence of atrial fibrillation.*
- This statement is nearly correct, but "left-sided heart failure" is broad. It is specifically in patients with **systolic dysfunction (HFrEF)** who are in **sinus rhythm** that digoxin lacks significant benefit beyond symptom control, and does not provide survival benefit.
Question 653: A 19-year-old G1P0 presents to the emergency department with severe abdominal pain. She states that the pain has been recurring every 3 to 5 minutes for the past 5 hours. She denies having regular prenatal care but recalls that her last menstrual period was about 9 months ago. She initially denies substance use but later admits to occasional prescription pain medication use during pregnancy. Her temperature is 98°F (37°C), blood pressure is 120/60 mmHg, pulse is 120/min, and respirations are 18/min. Tenderness is elicited in the lower abdominal quadrants. Clear fluid is seen in her vaginal vault with a fetal crown seen at 10 cm cervical dilation and +1 station. The patient is emergently taken into the labor and delivery suite, where she delivers a male infant with APGAR scores of 9 and 9 at 5 and 10 minutes, respectively. Several hours after delivery, the nurse notes that the infant is very irritable and crying in high pitches. The infant appears very diaphoretic with a runny nose and flailing limbs. What is the necessary pharmacological treatment for this patient?
A. Morphine (Correct Answer)
B. Phenobarbital
C. Naloxone
D. Diazepam
E. Acetaminophen
Explanation: ***Morphine***
- The infant is presenting with symptoms consistent with **neonatal abstinence syndrome (NAS)** due to maternal opioid use, requiring opioid replacement therapy.
- **Morphine** is the most appropriate pharmacological treatment to manage these withdrawal symptoms and gradually wean the infant.
*Phenobarbital*
- While **phenobarbital** can be used as a second-line agent for NAS, particularly if seizures are present or first-line opioids are ineffective, it is not the initial treatment of choice.
- Its primary role is in controlling severe **irritability** and **seizures** associated with withdrawal.
*Naloxone*
- **Naloxone** is an opioid antagonist and would worsen the withdrawal symptoms in an infant with NAS by abruptly blocking opioid receptors.
- It is used to reverse **acute opioid overdose** and respiratory depression, not for managing withdrawal.
*Diazepam*
- **Diazepam**, a benzodiazepine, might be considered in severe cases of NAS, especially if there are significant **seizures** or uncontrollable irritability.
- However, it is not the first-line treatment and could cause sedation or respiratory depression.
*Acetaminophen*
- **Acetaminophen** is a pain reliever and antipyretic but does not address the underlying **opioid withdrawal** symptoms.
- It would not alleviate the neurological symptoms, autonomic dysfunction, or gastrointestinal distress typical of NAS.
Question 654: A 25-year-old woman presents to the ED with nausea, vomiting, diarrhea, abdominal pain, and hematemesis after ingesting large quantities of a drug. Which of the following pairs a drug overdose with the correct antidote for this scenario?
A. Iron; deferoxamine (Correct Answer)
B. Organophosphate; physostigmine
C. Atropine; fomepizole
D. Aspirin; N-acetylcysteine
E. Acetaminophen; naloxone
Explanation: ***Iron; deferoxamine***
- The symptoms of **nausea, vomiting, diarrhea, abdominal pain, and hematemesis** are classic signs of **iron overdose**, which causes direct corrosive injury to the GI mucosa.
- **Deferoxamine** is a **chelating agent** specifically used to bind iron ions and facilitate their excretion, thus reversing iron toxicity.
*Organophosphate; physostigmine*
- **Organophosphate poisoning** presents with a **cholinergic crisis** (SLUDGE: salivation, lacrimation, urination, defecation, GI upset, emesis, miosis), but **hematemesis** is not a primary feature.
- **Physostigmine** is an acetylcholinesterase inhibitor used for atropine overdose, not organophosphate poisoning; **atropine** and **pralidoxime** are the antidotes for organophosphate.
*Atropine; fomepizole*
- **Atropine overdose** causes **anticholinergic symptoms** (dry mouth, blurred vision, tachycardia, urinary retention, delirium), not GI irritation and hematemesis.
- **Fomepizole** is an antidote for **methanol** or **ethylene glycol poisoning**, not atropine.
*Aspirin; N-acetylcysteine*
- **Aspirin overdose** (salicylate toxicity) results in **tinnitus, hyperventilation, metabolic acidosis, and altered mental status**, but **hematemesis** is less common than with iron.
- **N-acetylcysteine** is the antidote for acetaminophen overdose, not aspirin; aspirin overdose is treated with **alkalinization of urine** and **hemodialysis**.
*Acetaminophen; naloxone*
- **Acetaminophen overdose** primarily causes **hepatic toxicity**, initially presenting with non-specific GI symptoms, but **hematemesis** is atypical, and the main concern is liver damage.
- **Naloxone** is an opioid antagonist used to reverse opioid overdose, not acetaminophen.
Question 655: A 48-year-old woman comes to the physician for a follow-up examination. At her visit 1 month ago, her glomerular filtration rate (GFR) was 100 mL/min/1.73 m2 and her renal plasma flow (RPF) was 588 mL/min. Today, her RPF is 540 mL/min and her filtration fraction (FF) is 0.2. After her previous appointment, this patient was most likely started on a drug that has which of the following effects?
A. Inhibition of the renal Na-K-Cl cotransporter
B. Constriction of the afferent arteriole
C. Relaxation of urinary smooth muscle
D. Constriction of the efferent arteriole (Correct Answer)
E. Inhibition of vasopressin
Explanation: ***Constriction of the efferent arteriole***
- The previous GFR was 100 mL/min and RPF was 588 mL/min. For the follow-up, RPF is 540 mL/min and FF is 0.2. The new GFR can be calculated as FF × RPF = 0.2 × 540 = **108 mL/min**.
- The patient shows **increased GFR** (100→108 mL/min) with **decreased RPF** (588→540 mL/min), resulting in an **increased filtration fraction**.
- Medications that **constrict the efferent arteriole**, such as **NSAIDs**, produce this pattern by blocking prostaglandin synthesis. Prostaglandins normally cause vasodilation (predominantly of the afferent arteriole). When blocked, there is relatively more **efferent arteriolar constriction**, which increases glomerular hydrostatic pressure, thereby **increasing GFR while reducing overall RPF**.
*Inhibition of the renal Na-K-Cl cotransporter*
- This effect describes **loop diuretics** (e.g., furosemide), which increase sodium excretion and water diuresis.
- Loop diuretics typically cause a **decrease in GFR** due to reduced fluid volume and lower filtration pressure, which contradicts the slight increase in GFR observed.
*Constriction of the afferent arteriole*
- **Afferent arteriole constriction** (e.g., by NSAIDs in high doses or norepinephrine) would decrease blood flow into the glomerulus, leading to a **decrease in both RPF and GFR**.
- While RPF decreased in this case, GFR actually increased, making this option incorrect.
*Relaxation of urinary smooth muscle*
- Relaxation of urinary smooth muscle is characteristic of drugs like **alpha-blockers** (e.g., tamsulosin) or antimuscarinics used for conditions like benign prostatic hyperplasia or overactive bladder.
- This effect primarily impacts urine flow out of the bladder and does **not directly affect GFR or RPF** in the way described.
*Inhibition of vasopressin*
- Vasopressin (ADH) inhibition leads to **increased water excretion** and is seen with drugs like **vasopressin receptor antagonists** (vaptans) or ethanol.
- While it affects fluid balance, it typically causes a **decrease in GFR** due to hypovolemia and has no direct mechanism to increase GFR with decreased RPF as observed.
Question 656: A 17-year-old man presents to his primary care physician with bilateral tremor of the hands. He is a senior in high school and during the year, his grades have plummeted to the point that he is failing. He says his memory is now poor, and he has trouble focusing on tasks. His behavior has changed in the past 6 months in that he has frequent episodes of depression, separated by episodes of bizarre behavior, including excessive alcohol drinking and shoplifting. His parents have started to suspect that he is using street drugs, which he denies. His handwriting has become very sloppy. His parents have noted slight slurring of his speech. Family history is irrelevant. Physical examination reveals upper extremity tremors, mild dystonia of the upper extremities, and mild incoordination involving his hands. The patient’s eye is shown. Which of the following is the best initial management of this patient’s condition?
A. Watchful waiting
B. Oral zinc
C. Penicillamine (Correct Answer)
D. Oral deferasirox
E. Liver transplantation
Explanation: ***Penicillamine***
- This patient presents with classic **Wilson's disease**: tremor, dystonia, cognitive decline, psychiatric symptoms, and **Kayser-Fleischer rings** visible on examination.
- For **symptomatic patients with neurological manifestations**, **chelation therapy** is the first-line initial treatment.
- **Penicillamine** is a copper-chelating agent that promotes urinary excretion of copper and is the **standard initial therapy** for symptomatic Wilson's disease.
- Alternative chelators like **trientine** may be used if penicillamine is not tolerated, but penicillamine remains a primary option for initial management.
- While penicillamine can have side effects, it is necessary for this patient who requires urgent copper removal due to significant neurological symptoms.
*Oral zinc*
- Zinc works by blocking intestinal copper absorption and is effective in Wilson's disease management.
- However, zinc is **too slow-acting** for symptomatic patients and is primarily used for:
- **Maintenance therapy** after initial chelation
- **Asymptomatic or presymptomatic patients**
- Patients who cannot tolerate chelators
- This patient has significant neurological symptoms requiring more aggressive initial therapy with chelation.
*Watchful waiting*
- Wilson's disease is **progressive and fatal if untreated**.
- This patient has significant neurological, cognitive, and psychiatric symptoms indicating active disease.
- Delaying treatment would lead to irreversible neurological damage and further deterioration.
*Oral deferasirox*
- Deferasirox is an **iron-chelating agent** used for iron overload conditions (hemochromatosis, transfusional hemosiderosis).
- It has **no role in copper overload** and is not used in Wilson's disease management.
*Liver transplantation*
- Liver transplantation is reserved for:
- **Fulminant hepatic failure** with Wilson's disease
- **Decompensated cirrhosis** unresponsive to medical therapy
- It is a major surgical procedure, not appropriate for **initial management** of a patient with predominantly neurological symptoms who can be treated medically.
- This patient shows no evidence of acute liver failure or end-stage liver disease.
Question 657: A 23-year-old male is brought into the emergency department by his girlfriend following an argument. The patient’s girlfriend claims that she threatened to break up with him. He then called her saying he was going to kill himself. When she arrived at the patient’s home, she found him lying on the couch with empty alcohol bottles and multiple pill containers. The patient reports he does not remember everything he took, but says he ingested many pills about four hours ago. The patient’s temperature is 99°F (37.2°C), blood pressure is 110/68 mmHg, pulse is 88/min, and respirations are 25/min with an oxygen saturation of 98% O2 on room air. An arterial blood gas (ABG) is obtained, with results shown below:
pH: 7.47
pO2: 94 mmHg
pCO2: 24 mmHg
HCO3-: 22 mEq/L
You check on him a couple hours later, and the patient appears agitated. His girlfriend says he keeps grabbing his head, yelling about non-stop ringing in his ears. Labs and a repeat ABG shows:
pH: 7.30
pO2: 90 mmHg
pCO2: 22 mmHg
HCO3-: 9 mEq/L
Na+: 144 mEq/L
Cl-: 98 mEq/L
K+: 3.6 mEq/L
BUN: 18 mg/dL
Glucose: 100 mg/dL
Creatinine: 1.4 mg/dL
Which of the following is the best next step in management?
A. N-acetylcysteine
B. IV sodium bicarbonate (Correct Answer)
C. Acetazolamide
D. Activated charcoal
E. IV haloperidol
Explanation: ***IV sodium bicarbonate***
- The patient's condition, including **tinnitus**, agitation, and the ABG showing **mixed acid-base disturbance** (initially respiratory alkalosis, progressing to metabolic acidosis), is highly suggestive of **salicylate toxicity**. **IV sodium bicarbonate** is crucial here to **alkalinize the urine** and plasma, which promotes salicylate excretion and reduces its CNS penetration.
- The calculated **anion gap** (Na - (Cl + HCO3) = 144 - (98 + 9) = 37) is significantly elevated, indicating a **high anion gap metabolic acidosis**, which is characteristic of salicylate poisoning during the later stages.
*N-acetylcysteine*
- This is the antidote for **acetaminophen overdose**, which presents differently. The patient's symptoms, especially **tinnitus** and the specific acid-base derangements, are not consistent with acetaminophen toxicity.
- While it's important to consider co-ingestions, the dominant clinical picture points away from acetaminophen being the primary or most life-threatening agent here.
*Acetazolamide*
- **Acetazolamide** is a carbonic anhydrase inhibitor that **promotes renal bicarbonate wasting**, leading to **systemic metabolic acidosis** which would worsen the patient's existing acidosis.
- Systemic acidosis increases salicylate penetration into the CNS, potentially worsening neurotoxicity and clinical outcomes.
*Activated charcoal*
- Activated charcoal is effective in **adsorbing toxins** in the gastrointestinal tract, but its efficacy is time-dependent and significantly reduced if administered several hours post-ingestion.
- The patient ingested pills about four hours ago, and while it might be considered early on, it is not the most definitive treatment for established salicylate toxicity with severe acid-base derangements.
*IV haloperidol*
- **Haloperidol** is an antipsychotic used to treat agitation, but it does not address the underlying **toxidrome** or the severe metabolic derangements.
- Treating agitation symptomatically without addressing the root cause, especially in the context of a drug overdose, is inappropriate and could mask critical clinical deterioration.
Question 658: A 45-year-old woman comes to the physician because of a 6-month history of worsening involuntary movement of the left hand. Her symptoms are worse when she feels stressed at work. She has no history of serious illness and takes no medications. Neurological examination shows difficulty initiating movement and a tremor in the left hand at rest. The tremor decreases when the patient is asked to draw a circle. Which of the following is the most appropriate pharmacotherapy?
A. Trihexyphenidyl
B. Pramipexole (Correct Answer)
C. Clonazepam
D. Donepezil
E. Methimazole
Explanation: ***Pramipexole***
- This patient's symptoms of difficulty initiating movement, a **resting tremor** that improves with purposeful movement, and worsening with stress are characteristic of **Parkinson's disease**.
- **Pramipexole** is a **dopamine agonist** that directly stimulates dopamine receptors, effectively treating motor symptoms in Parkinson's disease.
*Trihexyphenidyl*
- **Trihexyphenidyl** is an **anticholinergic** agent primarily used for Parkinson's disease symptoms like **tremor** and **dystonia**, especially in younger patients.
- However, its side effects (e.g., dry mouth, blurred vision, confusion) are more pronounced in older patients, and **dopamine agonists** are generally preferred for initial treatment of motor symptoms in middle-aged adults.
*Clonazepam*
- **Clonazepam** is a **benzodiazepine** used to treat anxiety, seizures, and some movement disorders like essential tremor or restless legs syndrome.
- It is not a primary treatment for **Parkinson's disease** and would not address the underlying dopaminergic deficit or difficulty initiating movement.
*Donepezil*
- **Donepezil** is an **acetylcholinesterase inhibitor** used to treat the cognitive symptoms of Alzheimer's disease.
- It has no role in the treatment of the motor symptoms of **Parkinson's disease**.
*Methimazole*
- **Methimazole** is an **antithyroid medication** used to treat hyperthyroidism.
- It has no relevance to the neurological symptoms presented by the patient, which are indicative of a movement disorder.
Question 659: A previously healthy 29-year-old man comes to the emergency department because of a 4-day history of abdominal pain and confusion. Prior to the onset of the abdominal pain, he visited a festival where he consumed large amounts of alcohol. Examination shows a distended abdomen, decreased bowel sounds, and diffuse tenderness to palpation. There is motor weakness in the upper extremities. Sensation is decreased over the upper and lower extremities. Laboratory studies show no abnormalities. Which of the following is the most appropriate therapy for this patient's condition?
A. Chlordiazepoxide
B. Ethylenediaminetetraacetic acid
C. Intravenous immunoglobulin
D. Chloroquine
E. Hemin (Correct Answer)
Explanation: ***Hemin***
- The patient's presentation with **abdominal pain**, **confusion**, **motor weakness**, **sensory deficits**, and a recent history of **alcohol consumption** (a known trigger) is highly suggestive of **acute intermittent porphyria (AIP)**.
- **Hemin** is the most appropriate therapy for acute porphyria attacks as it inhibits **aminolevulinate synthase (ALA synthase)**, the rate-limiting enzyme in heme synthesis, thereby reducing the harmful buildup of neurotoxic porphyrin precursors.
*Chlordiazepoxide*
- **Chlordiazepoxide** is a **benzodiazepine** used to treat alcohol withdrawal symptoms, anxiety, and insomnia.
- While the patient consumed alcohol, the symptoms of abdominal pain, neurologic deficits, and confusion point away from typical alcohol withdrawal and more towards an underlying metabolic disorder.
*Ethylenediaminetetraacetic acid*
- **Ethylenediaminetetraacetic acid (EDTA)** is a chelating agent primarily used to treat **lead poisoning** by binding to heavy metals.
- The symptoms described do not fit the typical presentation of lead poisoning, and there's no indication of heavy metal exposure.
*Intravenous immunoglobulin*
- **Intravenous immunoglobulin (IVIG)** is used to treat various autoimmune and inflammatory disorders, such as Guillain-Barré syndrome or myasthenia gravis.
- While the patient has neurological symptoms, the constellation of abdominal pain and confusion triggered by alcohol is not characteristic of conditions for which IVIG is first-line therapy.
*Chloroquine*
- **Chloroquine** is an antimalarial drug also used in the treatment of some autoimmune conditions like lupus.
- It is **contraindicated** in patients with **porphyrias** (especially porphyria cutanea tarda) as it can exacerbate the condition by interfering with porphyrin metabolism.
Question 660: A 45-year-old male presents to the emergency room for toe pain. He reports that his right great toe became acutely painful, red, and swollen approximately five hours prior. He has had one similar prior episode six months ago that resolved with indomethacin. His medical history is notable for obesity, hypertension, and alcohol abuse. He currently takes hydrochlorothiazide (HCTZ). On physical examination, his right great toe is swollen, erythematous, and exquisitely tender to light touch. The patient is started on a new medication that decreases leukocyte migration and mitosis, and his pain eventually resolves; however, he develops nausea and vomiting as a result of therapy. Which of the following underlying mechanisms of action is characteristic of this patient’s new medication?
A. Inhibits microtubule polymerization (Correct Answer)
B. Prevents conversion of xanthine to uric acid
C. Decreases cyclooxygenase-induced production of prostaglandins
D. Decreases phospholipase A2-induced production of arachidonic acid
E. Metabolizes uric acid to water-soluble allantoin
Explanation: ***Inhibits microtubule polymerization***
- The patient's presentation with acute, exquisitely painful, red, and swollen great toe, history of similar episodes, and risk factors (obesity, hypertension, alcohol abuse, HCTZ use) are highly suggestive of **acute gout**. The medication's effect of decreasing **leukocyte migration and mitosis** with side effects of nausea and vomiting points to **colchicine**.
- **Colchicine** exerts its anti-inflammatory effects by binding to **tubulin** and inhibiting its polymerization into microtubules, thereby disrupting leukocyte function, migration, and mitosis.
*Prevents conversion of xanthine to uric acid*
- This mechanism of action describes **allopurinol** and **febuxostat**, which are **xanthine oxidase inhibitors** used for chronic uric acid lowering to prevent future gout attacks, not for acute treatment.
- These medications do not primarily decrease leukocyte migration or cause acute gastrointestinal distress like colchicine.
*Decreases cyclooxygenase-induced production of prostaglandins*
- This is the mechanism of action for **NSAIDs** (like indomethacin, which the patient previously used), which primarily reduce pain and inflammation by inhibiting the synthesis of prostaglandins.
- While NSAIDs are effective for acute gout, they do not decrease leukocyte migration and mitosis directly in the way colchicine does.
*Decreases phospholipase A2-induced production of arachidonic acid*
- This mechanism describes **corticosteroids** (e.g., prednisone), which inhibit the entire pathway of arachidonic acid metabolism, leading to reduced production of inflammatory mediators.
- Corticosteroids are used for acute gout, but their mechanism is broader than just affecting leukocyte migration and mitosis, and they don't exclusively cause the specific GI side effects described as the primary concern.
*Metabolizes uric acid to water-soluble allantoin*
- This describes the mechanism of action for **rasburicase** and **pegloticase**, which are **recombinant uricases** used to break down uric acid in severe cases (e.g., tumor lysis syndrome, refractory chronic gout).
- These agents are not typically used for acute gout attacks and act to reduce uric acid levels, not by inhibiting leukocyte function directly as was described.