A 27-year-old man is brought to the emergency department by his girlfriend. The patient is a seasonal farm worker and was found laying down and minimally responsive under a tree. The patient was immediately brought to the emergency department. The patient has a past medical history of IV drug use, marijuana use, and alcohol use. His current medications include ibuprofen. His temperature is 98.2°F (36.8°C), blood pressure is 100/55 mmHg, pulse is 60/min, respirations are 15/min, and oxygen saturation is 98% on room air. On physical exam, the patient's extremities are twitching, and his clothes are soaked in urine and partially removed. The patient is also drooling and coughs regularly. Which of the following is the best next step in management?
Q32
A 50-year-old man is brought to the emergency department by his wife with acute onset confusion, disorientation, and agitation. The patient's wife reports that he has diabetic gastroparesis for which he takes domperidone in 3 divided doses every day. He also takes insulin glargine and insulin lispro for management of type 1 diabetes mellitus and telmisartan for control of hypertension. Today, she says the patient forgot to take his morning dose of domperidone to work and instead took 4 tablets of scopolamine provided to him by a coworker. Upon returning home after 4 hours, he complained of dizziness and became increasingly drowsy and confused. His temperature is 38.9°C (102.0°F), pulse rate is 112 /min, blood pressure is 140/96 mm Hg, and respiratory rate is 20/min. On physical examination, the skin is dry. Pupils are dilated. There are myoclonic jerks of the jaw present. Which of the following is the most likely cause of this patient’s symptoms?
Q33
A 56-year-old man presents seeking treatment for his baldness. He says he has noticed a bald patch in the center of his head which has increased in size over the past year. Physical examination and diagnostic tests show no evidence of an infectious cause. The patient is prescribed a drug be taken daily. After 4 months, the patient returns for follow-up and says that his hair growth has increased significantly. He denies any significant side effects except for a slight decrease in his sex drive. Which of the following is most likely the mechanism of action of the drug this patient was prescribed?
Q34
A 43-year-old woman is brought to the emergency department 10 minutes after the sudden onset of shortness of breath, dry cough, nausea, and an itchy rash. The symptoms started 15 minutes after she had dinner with her husband and her two sons at a local seafood restaurant. The patient has a 2-year history of hypertension treated with enalapril. She also uses an albuterol inhaler as needed for exercise-induced asthma. Empiric treatment with her inhaler has not notably improved her current symptoms. She has smoked one pack of cigarettes daily for the last 20 years. She drinks one to two glasses of wine every other day. She has never used illicit drugs. She appears uncomfortable and anxious. Her pulse is 124/min, respirations are 22/min and slightly labored, and blood pressure is 82/68 mm Hg. Examination of the skin shows erythematous patches and wheals over her trunk, back, upper arms, and thighs. Her lips appear slightly swollen. Expiratory wheezing is heard throughout both lung fields. The remainder of the physical examination shows no abnormalities. Which of the following is the most appropriate next step in the management of this patient?
Q35
An investigator is studying physiological changes in the autonomic nervous system in response to different stimuli. 40 μg of epinephrine is infused in a healthy volunteer over a period of 5 minutes, and phenoxybenzamine is subsequently administered. Which of the following effects is most likely to be observed in this volunteer?
Q36
A 30-year-old woman presents to an urgent care center with progressively worsening cough and difficulty breathing. She has had similar prior episodes since childhood, one of which required intubation with mechanical ventilation. On physical exam, she appears anxious and diaphoretic, with diffuse wheezes and diminished breath sounds bilaterally. First-line treatment for this patient’s symptoms acts by which of the following mechanisms of action?
Q37
A 47-year-old woman comes to the physician because of repetitive tongue twisting and abnormal movements of the hands and legs that started several days ago. She has a 2-year history of schizophrenia that has been controlled with fluphenazine. Two weeks ago, she was switched to risperidone. Examination shows protrusion of the tongue and smacking of the lips. She makes twisting movements of the arms and frequently taps her right foot. Which of the following is the most likely diagnosis?
Q38
A 30-year-old man presents with fatigue and low energy. He says that he has been "feeling down" and tired on most days for the last 3 years. He also says that he has had difficulty concentrating and has been sleeping excessively. The patient denies any manic or hypomanic symptoms. He also denies any suicidal ideation or preoccupation with death. A physical examination is unremarkable. Laboratory findings are significant for the following:
Serum glucose (fasting) 88 mg/dL
Serum electrolytes Sodium 142 mEq/L; Potassium: 3.9 mEq/L; Chloride: 101 mEq/L
Serum creatinine 0.8 mg/dL
Blood urea nitrogen 10 mg/dL
Hemoglobin (Hb %) 15 g/dL
Mean corpuscular volume (MCV) 85 fl
Reticulocyte count 1%
Erythrocyte count 5.1 million/mm3
Thyroid-stimulating hormone 3.5 μU/mL
Medication is prescribed to this patient that increases norepinephrine neurotransmission. After 2 weeks, the patient returns for follow-up and complains of dizziness, dry mouth, and constipation. Which of the following drugs was most likely prescribed to this patient?
Q39
A 25-year-old man is admitted to the hospital with acute onset dyspnea, chest pain, and fainting. The medical history is significant for infective endocarditis at the age of 17 years, and intravenous drug abuse prior to the disease. He reports a history of mild dyspnea on exertion. Currently, his only medication is duloxetine, which the patient takes for his depression. The vital signs include: blood pressure 160/100 mm Hg, heart rate 103/min, respiratory rate 21/min, temperature 38.1℃ (100.9℉), and oxygen saturation is 91% on room air. On physical examination, the patient is dyspneic, restless, confused, and anxious. His pupils are dilated, symmetrical, and reactive to light. The patient's skin is pale with acrocyanosis and clear without signs of injection. There is bilateral jugular venous distention. On lung auscultation, there are bilateral crackles at the lower lobes. Cardiac auscultation shows presence of an S3 gallop, an accentuated S2 best heard at the tricuspid and pulmonary areas, and a pansystolic grade 2/6 murmur over the tricuspid area. Abdominal examination is significant for enlarged liver palpated 3 cm below the costal margin. The complete blood count is only significant for decreased hemoglobin. His rapid HIV test is negative. Which of the following is the most likely cause of the condition of this patient?
Q40
A 68-year-old man presents with urinary retention for the past week. He says his symptoms onset gradually almost immediately after being prescribed a new medication for his depression. He states that he has increased his fluid intake to try to help the issue, but this has been ineffective. He also mentions that he has been having problems with constipation and dry mouth. His past medical history is significant for major depressive disorder, diagnosed 6 months ago. The patient denies any history of smoking, alcohol consumption, or recreational drug use. He is afebrile, and his vital signs are within normal limits. A physical examination is unremarkable. A urinalysis is normal. Which of the following medications was this patient most likely prescribed for his depression?
Cholinergic/Adrenergic drugs US Medical PG Practice Questions and MCQs
Question 31: A 27-year-old man is brought to the emergency department by his girlfriend. The patient is a seasonal farm worker and was found laying down and minimally responsive under a tree. The patient was immediately brought to the emergency department. The patient has a past medical history of IV drug use, marijuana use, and alcohol use. His current medications include ibuprofen. His temperature is 98.2°F (36.8°C), blood pressure is 100/55 mmHg, pulse is 60/min, respirations are 15/min, and oxygen saturation is 98% on room air. On physical exam, the patient's extremities are twitching, and his clothes are soaked in urine and partially removed. The patient is also drooling and coughs regularly. Which of the following is the best next step in management?
A. Atropine (Correct Answer)
B. Electroencephalography
C. Urine toxicology
D. Supportive therapy and monitoring
E. Lorazepam
Explanation: ***Atropine***
- The patient's symptoms (twitching, drooling, urinary incontinence, bradycardia, hypotension, and bronchorrhea evidenced by regular coughing) are classic for **organophosphate poisoning**, which causes a **cholinergic crisis**.
- **Atropine** is the primary antidote, acting as a competitive antagonist at **muscarinic acetylcholine receptors**, and is crucial for reversing severe cholinergic symptoms.
*Electroencephalography*
- While seizures can occur with some toxic ingestions, an **EEG** is not the immediate priority given the clear signs of cholinergic toxicity and the need for rapid antidotal therapy.
- An EEG might be considered later if the cause of neurological symptoms remains unclear or to assess for non-convulsive status epilepticus.
*Urine toxicology*
- While a **urine toxicology screen** could be useful for identifying other potential substances, the clinical presentation is highly suggestive of **organophosphate poisoning**, and immediate action with an antidote is more critical than waiting for lab results.
- Delaying specific treatment for presumptive toxicology results could be detrimental to the patient's outcome.
*Supportive therapy and monitoring*
- **Supportive care** (e.g., airway management, intravenous fluids) is always important, but in this specific scenario, a targeted antidote is required to address the underlying toxicity effectively.
- Relying solely on monitoring without administering specific treatment would allow the patient's cholinergic crisis to worsen, potentially leading to respiratory failure.
*Lorazepam*
- **Lorazepam** is a benzodiazepine used to treat seizures and agitation. While the patient has twitching, this is likely part of the cholinergic crisis and not necessarily a primary seizure disorder.
- **Lorazepam** would not address the fundamental cholinergic overload and would not be the best first-line treatment compared to **atropine** for organophosphate poisoning.
Question 32: A 50-year-old man is brought to the emergency department by his wife with acute onset confusion, disorientation, and agitation. The patient's wife reports that he has diabetic gastroparesis for which he takes domperidone in 3 divided doses every day. He also takes insulin glargine and insulin lispro for management of type 1 diabetes mellitus and telmisartan for control of hypertension. Today, she says the patient forgot to take his morning dose of domperidone to work and instead took 4 tablets of scopolamine provided to him by a coworker. Upon returning home after 4 hours, he complained of dizziness and became increasingly drowsy and confused. His temperature is 38.9°C (102.0°F), pulse rate is 112 /min, blood pressure is 140/96 mm Hg, and respiratory rate is 20/min. On physical examination, the skin is dry. Pupils are dilated. There are myoclonic jerks of the jaw present. Which of the following is the most likely cause of this patient’s symptoms?
A. Hypoglycemia
B. Domperidone overdose
C. Diabetic ketoacidosis
D. Heatstroke
E. Scopolamine overdose (Correct Answer)
Explanation: ***Scopolamine overdose***
- The patient exhibits classic signs of **anticholinergic toxicity**, including acute onset confusion, disorientation, agitation, dilated pupils, dry skin, fever, and tachycardia. **Scopolamine** is a potent anticholinergic agent.
- The history of taking four tablets of scopolamine, especially after forgetting his domperidone (which is a dopamine receptor antagonist, indirectly affecting cholinergic tone), strongly points to an overdose.
*Hypoglycemia*
- While confusion and dizziness can be symptoms of **hypoglycemia**, the presence of dilated pupils, dry skin, fever, and agitation are inconsistent with this diagnosis.
- Patients with hypoglycemia typically present with **sweating**, pallor, and a normal or constricted pupil size.
*Domperidone overdose*
- **Domperidone** is a dopamine receptor antagonist and would generally cause **extrapyramidal symptoms**, hyperprolactinemia, or QT prolongation, not the anticholinergic syndrome observed.
- An overdose would likely lead to symptoms such as **dystonia**, **akathisia**, or sedation, which are distinct from the patient's presentation.
*Diabetic ketoacidosis*
- **Diabetic ketoacidosis (DKA)** typically presents with severe hyperglycemia, metabolic acidosis, fruity breath, and deep, rapid breathing (**Kussmaul respirations**).
- While confusion can occur, the lack of respiratory distress, the presence of markedly dilated pupils, and dry skin are not typical for DKA.
*Heatstroke*
- While **hyperthermia** and altered mental status are features of heatstroke, the presence of dilated pupils and agitation is also characteristic of anticholinergic toxicity.
- The specific history of scopolamine ingestion makes anticholinergic overdose a more probable and direct cause than primary heatstroke, especially given the rapid onset after drug intake.
Question 33: A 56-year-old man presents seeking treatment for his baldness. He says he has noticed a bald patch in the center of his head which has increased in size over the past year. Physical examination and diagnostic tests show no evidence of an infectious cause. The patient is prescribed a drug be taken daily. After 4 months, the patient returns for follow-up and says that his hair growth has increased significantly. He denies any significant side effects except for a slight decrease in his sex drive. Which of the following is most likely the mechanism of action of the drug this patient was prescribed?
A. GnRH analog
B. Androgen receptor activation
C. Androgen receptor blocker
D. α1 adrenergic antagonist
E. 5α reductase inhibitor (Correct Answer)
Explanation: ***5α reductase inhibitor***
- The patient's presentation of male pattern baldness (androgenic alopecia) and improved hair growth with a **decreased sex drive** strongly suggests the use of a 5α-reductase inhibitor, such as **finasteride**.
- These drugs inhibit the conversion of **testosterone to dihydrotestosterone (DHT)**, which is the primary androgen responsible for hair follicle miniaturization in androgenic alopecia, while the decreased DHT can lead to reduced libido.
*GnRH analog*
- **GnRH analogs** initially stimulate and then suppress the release of LH and FSH, leading to a significant reduction in sex hormone levels, which would likely cause more severe side effects like hot flashes and more pronounced sexual dysfunction.
- While they can reduce androgen levels, they are typically used for conditions like prostate cancer or precocious puberty, not primarily for male pattern baldness due to their profound systemic effects.
*Androgen receptor activation*
- **Androgen receptor activation** would exacerbate male pattern baldness, as DHT acts by binding to these receptors in hair follicles.
- Drugs that activate androgen receptors, such as exogenous testosterone, typically lead to increased hair loss on the scalp and other androgenic effects.
*Androgen receptor blocker*
- **Androgen receptor blockers** (e.g., spironolactone) can reduce hair loss in women but are less commonly used in men for male pattern baldness due to feminizing side effects and broader anti-androgenic effects beyond just DHT.
- While they reduce the effect of androgens, the specific side effect profile and clinical use for male pattern baldness do not align as perfectly as a 5α-reductase inhibitor.
*α1 adrenergic antagonist*
- **α1 adrenergic antagonists** (e.g., tamsulosin) are primarily used to treat benign prostatic hyperplasia (BPH) or hypertension by relaxing smooth muscle.
- These drugs have no direct role in hair growth or the mechanism of androgenetic alopecia and do not typically cause a decrease in sex drive as a primary or common side effect in this context.
Question 34: A 43-year-old woman is brought to the emergency department 10 minutes after the sudden onset of shortness of breath, dry cough, nausea, and an itchy rash. The symptoms started 15 minutes after she had dinner with her husband and her two sons at a local seafood restaurant. The patient has a 2-year history of hypertension treated with enalapril. She also uses an albuterol inhaler as needed for exercise-induced asthma. Empiric treatment with her inhaler has not notably improved her current symptoms. She has smoked one pack of cigarettes daily for the last 20 years. She drinks one to two glasses of wine every other day. She has never used illicit drugs. She appears uncomfortable and anxious. Her pulse is 124/min, respirations are 22/min and slightly labored, and blood pressure is 82/68 mm Hg. Examination of the skin shows erythematous patches and wheals over her trunk, back, upper arms, and thighs. Her lips appear slightly swollen. Expiratory wheezing is heard throughout both lung fields. The remainder of the physical examination shows no abnormalities. Which of the following is the most appropriate next step in the management of this patient?
A. Intravenous diphenhydramine and ranitidine administration
B. Intravenous methylprednisolone administration
C. Endotracheal intubation
D. Nebulized albuterol administration
E. Intramuscular epinephrine administration (Correct Answer)
Explanation: ***Intramuscular epinephrine administration***
- The patient presents with classic signs of **anaphylaxis**, including **acute onset**, **skin manifestations (hives, angioedema)**, **respiratory distress (shortness of breath, wheezing)**, and **hypotension (BP 82/68 mmHg)**, all following a potential allergen exposure (seafood).
- **Epinephrine** is the **first-line treatment** for anaphylaxis due to its **alpha-1 adrenergic effects** (vasoconstriction, increasing blood pressure and reducing angioedema) and **beta-2 adrenergic effects** (bronchodilation, improving respiratory symptoms).
*Intravenous diphenhydramine and ranitidine administration*
- While **antihistamines (H1 blockers like diphenhydramine and H2 blockers like ranitidine)** can help alleviate cutaneous symptoms like itching and urticaria in anaphylaxis, they are **second-line agents** and do not address the life-threatening respiratory or cardiovascular compromise.
- Relying solely on antihistamines in a hypotensive patient with respiratory distress would delay definitive treatment and risk clinical deterioration.
*Intravenous methylprednisolone administration*
- **Corticosteroids** like methylprednisolone are useful in anaphylaxis to prevent **biphasic reactions** and reduce prolonged inflammation, but their onset of action is **slow** (hours) and they are **not effective** for immediate life-threatening symptoms.
- They should be administered after epinephrine and other immediate supportive measures are in place.
*Endotracheal intubation*
- **Endotracheal intubation** is a major invasive procedure for airway management and is considered when there is **imminent airway obstruction** or **refractory respiratory failure**.
- While the patient has respiratory distress, the initial management for anaphylaxis-related airway compromise involves epinephrine, which can rapidly improve bronchospasm and laryngeal edema, potentially averting the need for intubation.
*Nebulized albuterol administration*
- **Nebulized albuterol** is a **beta-2 agonist** that can relieve bronchospasm and is appropriate for asthma exacerbations or isolated bronchoconstriction.
- However, in anaphylaxis, the respiratory symptoms are just one component of a multi-system reaction that includes cardiovascular collapse and widespread vasodilation, which albuterol alone cannot address. Epinephrine is preferred as it has both **beta-2 and alpha-1 agonist** effects.
Question 35: An investigator is studying physiological changes in the autonomic nervous system in response to different stimuli. 40 μg of epinephrine is infused in a healthy volunteer over a period of 5 minutes, and phenoxybenzamine is subsequently administered. Which of the following effects is most likely to be observed in this volunteer?
A. Increased secretion of insulin
B. Increased pressure inside the bladder
C. Decreased breakdown of muscle glycogen
D. Decreased secretion of aqueous humor (Correct Answer)
E. Increased peripheral vascular resistance
Explanation: ***Decreased secretion of aqueous humor***
- Epinephrine activates **beta-2 adrenergic receptors** in the ciliary epithelium, which **reduces aqueous humor production**.
- After phenoxybenzamine (an irreversible **alpha-blocker**) is administered, the **beta-receptor effects persist** because phenoxybenzamine only blocks alpha receptors.
- Therefore, the beta-2 mediated reduction in aqueous humor secretion continues, making this the correct answer.
*Increased secretion of insulin*
- Epinephrine **inhibits insulin secretion** via alpha-2 receptor activation on pancreatic beta cells.
- Even after alpha-blockade with phenoxybenzamine, beta-2 receptor activation can still suppress insulin release.
- Insulin secretion would remain decreased or normal, not increased.
*Increased pressure inside the bladder*
- Epinephrine causes **beta-2 mediated relaxation** of the detrusor muscle (bladder wall).
- After phenoxybenzamine blocks alpha-1 receptors at the internal sphincter, the beta-2 relaxation effects persist.
- This would **decrease bladder pressure**, not increase it.
*Decreased breakdown of muscle glycogen*
- Epinephrine strongly stimulates **beta-2 receptors** in skeletal muscle, promoting **glycogenolysis** (breakdown of glycogen).
- After alpha-blockade, beta receptor activation continues, so glycogen breakdown remains **increased**, not decreased.
*Increased peripheral vascular resistance*
- Initially, epinephrine causes alpha-1 mediated vasoconstriction and increased peripheral resistance.
- However, after **phenoxybenzamine blocks alpha receptors**, only beta-2 effects remain.
- Beta-2 activation causes **vasodilation** in skeletal muscle vessels, leading to **decreased peripheral vascular resistance** (this is the classic "epinephrine reversal" phenomenon).
- Therefore, peripheral resistance would be **decreased**, not increased.
Question 36: A 30-year-old woman presents to an urgent care center with progressively worsening cough and difficulty breathing. She has had similar prior episodes since childhood, one of which required intubation with mechanical ventilation. On physical exam, she appears anxious and diaphoretic, with diffuse wheezes and diminished breath sounds bilaterally. First-line treatment for this patient’s symptoms acts by which of the following mechanisms of action?
A. Beta-2 antagonist
B. Beta-1 agonist
C. Beta-2 agonist (Correct Answer)
D. Beta-1 antagonist
E. Beta-3 agonist
Explanation: ***Beta-2 agonist***
- The patient's presentation with **worsening cough**, **difficulty breathing**, **diffuse wheezes**, and a history of similar episodes since childhood requiring intubation is highly suggestive of an **acute asthma exacerbation**.
- **Short-acting beta-2 agonists (SABAs)** like albuterol are the **first-line treatment** for acute asthma symptoms, as they cause rapid **bronchodilation** by stimulating **beta-2 receptors** on airway smooth muscle.
*Beta-2 antagonist*
- A **beta-2 antagonist** would cause **bronchoconstriction**, exacerbating the patient's respiratory distress rather than relieving it.
- This class of drugs is generally contraindicated in patients with asthma unless used with extreme caution and for specific indications like glaucoma, where topical beta-blockers might be used.
*Beta-1 agonist*
- **Beta-1 agonists** primarily affect the **heart**, increasing **heart rate** and **contractility**.
- While they might have some minor beta-2 effects at higher doses, their primary action is not bronchodilation and they would be associated with significant unwanted cardiac side effects in this setting.
*Beta-1 antagonist*
- **Beta-1 antagonists** (beta-blockers) primarily act on the **heart** to decrease heart rate and contractility and would have no beneficial effect on bronchoconstriction.
- Non-selective beta-blockers can even cause **bronchoconstriction** by blocking beta-2 receptors, making them potentially harmful in asthma.
*Beta-3 agonist*
- **Beta-3 agonists** are primarily involved in **lipolysis** and **bladder relaxation**.
- They are used for conditions like overactive bladder but have no significant role in the treatment of acute asthma exacerbations.
Question 37: A 47-year-old woman comes to the physician because of repetitive tongue twisting and abnormal movements of the hands and legs that started several days ago. She has a 2-year history of schizophrenia that has been controlled with fluphenazine. Two weeks ago, she was switched to risperidone. Examination shows protrusion of the tongue and smacking of the lips. She makes twisting movements of the arms and frequently taps her right foot. Which of the following is the most likely diagnosis?
A. Acute dystonia
B. Akathisia
C. Tardive dyskinesia (Correct Answer)
D. Neuroleptic malignant syndrome
E. Cerebellar stroke
Explanation: ***Tardive dyskinesia***
- This condition involves **involuntary, repetitive movements** such as **tongue twisting, lip smacking, and abnormal movements of the hands and legs**, which are classic symptoms described.
- It typically occurs after **prolonged use of dopamine receptor-blocking agents** (antipsychotics), usually requiring **months to years of exposure**. This patient had been on fluphenazine for 2 years.
- The **switch from fluphenazine to risperidone** may have **unmasked or exacerbated** pre-existing tardive dyskinesia, as changes in antipsychotic regimens can alter the balance of dopamine blockade.
*Acute dystonia*
- Characterized by **sudden, sustained muscle contractions** causing abnormal postures, often affecting the neck, eyes (oculogyric crisis), or trunk.
- Typically occurs within **hours to days** of initiating or increasing antipsychotic medication.
- While timing could fit, the **repetitive, choreiform nature of the movements** (rather than sustained muscle contractions) makes tardive dyskinesia more likely.
*Akathisia*
- Presents as a subjective feeling of **inner restlessness** and an objective compulsion to move, such as frequently shifting weight, pacing, or inability to sit still.
- Although the patient taps her foot, the predominant symptoms are **involuntary orofacial and limb movements** without described subjective restlessness, which are not typical of akathisia.
*Neuroleptic malignant syndrome*
- A life-threatening reaction characterized by a **tetrad of symptoms**: high fever, severe muscle rigidity ("lead-pipe" rigidity), autonomic instability (tachycardia, labile blood pressure, diaphoresis), and altered mental status.
- The patient's presentation lacks these severe systemic signs and is instead focused on involuntary hyperkinetic movements.
*Cerebellar stroke*
- A stroke affecting the cerebellum would primarily cause **ataxia, nystagmus, dysarthria, and problems with coordination and balance**.
- The described symptoms are primarily **involuntary hyperkinetic movements** related to chronic dopamine pathway dysfunction from antipsychotic use, not acute cerebellar pathology.
Question 38: A 30-year-old man presents with fatigue and low energy. He says that he has been "feeling down" and tired on most days for the last 3 years. He also says that he has had difficulty concentrating and has been sleeping excessively. The patient denies any manic or hypomanic symptoms. He also denies any suicidal ideation or preoccupation with death. A physical examination is unremarkable. Laboratory findings are significant for the following:
Serum glucose (fasting) 88 mg/dL
Serum electrolytes Sodium 142 mEq/L; Potassium: 3.9 mEq/L; Chloride: 101 mEq/L
Serum creatinine 0.8 mg/dL
Blood urea nitrogen 10 mg/dL
Hemoglobin (Hb %) 15 g/dL
Mean corpuscular volume (MCV) 85 fl
Reticulocyte count 1%
Erythrocyte count 5.1 million/mm3
Thyroid-stimulating hormone 3.5 μU/mL
Medication is prescribed to this patient that increases norepinephrine neurotransmission. After 2 weeks, the patient returns for follow-up and complains of dizziness, dry mouth, and constipation. Which of the following drugs was most likely prescribed to this patient?
A. Clonidine
B. Lithium
C. Paroxetine
D. Venlafaxine (Correct Answer)
E. Phenylephrine
Explanation: ***Venlafaxine***
- This patient likely suffers from **persistent depressive disorder (dysthymia)** given the chronic fatigue, low energy, and depressed mood for over 2 years without manic/hypomanic episodes.
- **Venlafaxine** is a **serotonin-norepinephrine reuptake inhibitor (SNRI)** that increases both serotonin and norepinephrine levels by blocking their reuptake at nerve terminals, thereby enhancing norepinephrine neurotransmission.
- Common side effects include **dizziness, dry mouth, and constipation** due to anticholinergic effects and increased noradrenergic activity.
*Clonidine*
- **Clonidine** is an **alpha-2 adrenergic agonist** that reduces sympathetic outflow by activating presynaptic alpha-2 receptors, effectively decreasing norepinephrine release, which is contrary to the question's premise of increasing norepinephrine neurotransmission.
- It is primarily used to treat **hypertension** and **ADHD**, and its side effects can include sedation and dry mouth, but it would not be prescribed to enhance norepinephrine activity.
*Lithium*
- **Lithium** is a mood stabilizer primarily used in the treatment of **bipolar disorder** and is not typically prescribed as a standalone antidepressant to increase norepinephrine neurotransmission.
- Its side effects include **tremor, polyuria, polydipsia, and thyroid dysfunction**, which do not match the described side effect profile.
*Paroxetine*
- **Paroxetine** is a **selective serotonin reuptake inhibitor (SSRI)**, primarily increasing serotonin levels. It does not significantly increase norepinephrine neurotransmission.
- While it can cause side effects like **dry mouth and constipation**, it would not fit the description of a drug that increases norepinephrine neurotransmission.
*Phenylephrine*
- **Phenylephrine** is an **alpha-1 adrenergic agonist** used as a decongestant or to increase blood pressure by directly stimulating postsynaptic alpha-1 receptors rather than enhancing neurotransmission through reuptake inhibition.
- It would not be used to treat depression, and its side effects include **hypertension and reflex bradycardia**, which are not reported in the patient.
Question 39: A 25-year-old man is admitted to the hospital with acute onset dyspnea, chest pain, and fainting. The medical history is significant for infective endocarditis at the age of 17 years, and intravenous drug abuse prior to the disease. He reports a history of mild dyspnea on exertion. Currently, his only medication is duloxetine, which the patient takes for his depression. The vital signs include: blood pressure 160/100 mm Hg, heart rate 103/min, respiratory rate 21/min, temperature 38.1℃ (100.9℉), and oxygen saturation is 91% on room air. On physical examination, the patient is dyspneic, restless, confused, and anxious. His pupils are dilated, symmetrical, and reactive to light. The patient's skin is pale with acrocyanosis and clear without signs of injection. There is bilateral jugular venous distention. On lung auscultation, there are bilateral crackles at the lower lobes. Cardiac auscultation shows presence of an S3 gallop, an accentuated S2 best heard at the tricuspid and pulmonary areas, and a pansystolic grade 2/6 murmur over the tricuspid area. Abdominal examination is significant for enlarged liver palpated 3 cm below the costal margin. The complete blood count is only significant for decreased hemoglobin. His rapid HIV test is negative. Which of the following is the most likely cause of the condition of this patient?
A. Coronary atherosclerosis
B. Cocaine toxicity (Correct Answer)
C. Sepsis
D. Acute viral hepatitis
E. Duloxetine overdose
Explanation: **Cocaine toxicity**
- This patient's acute symptoms, including **dyspnea**, **chest pain**, **tachycardia**, **hypertension**, **dilated pupils**, and **altered mental status (restlessness, confusion, anxiety)**, are highly consistent with acute **cocaine toxicity**.
- Cocaine use can precipitate acute cardiac events like **myocardial ischemia** or **tachyarrhythmias**, leading to cardiogenic shock, and can also cause **pulmonary edema** from sympathetic overstimulation and direct cardiotoxicity, explaining the crackles and jugular venous distention.
*Coronary atherosclerosis*
- While coronary atherosclerosis can cause acute chest pain and dyspnea, it is less likely in a **25-year-old** without significant risk factors other than a history of intravenous drug abuse, which is a stronger risk factor for conditions like endocarditis or acute stimulant-induced cardiac events.
- The prominent neurological symptoms like **dilated pupils**, **confusion**, and **anxiety** point strongly towards a stimulant-induced cause rather than primary atherosclerosis.
*Sepsis*
- Although the patient has a fever (38.1°C), tachycardia, and altered mental status, common in sepsis, the presence of **hypertension (160/100 mmHg)** and **dilated pupils** makes sepsis less likely as the primary cause. Sepsis typically presents with **hypotension** and sometimes constricted pupils in opioid-related cases.
- The distinct cardiac findings, such as an **accentuated S2** and new **pansystolic murmur** (suggesting tricuspid regurgitation, possibly exacerbated by right heart strain), are not typical initial presentations of sepsis.
*Acute viral hepatitis*
- Acute viral hepatitis primarily affects the liver, causing symptoms like **jaundice**, **fatigue**, **nausea**, and **abdominal pain**.
- It does not typically cause acute onset **dyspnea**, **chest pain**, **hypertension**, **tachycardia**, **dilated pupils**, or **pulmonary crackles** as the prominent features described in this patient.
*Duloxetine overdose*
- Duloxetine is a serotonin-norepinephrine reuptake inhibitor. Overdose can cause symptoms like **tachycardia**, **hypertension**, and **dilated pupils**, which overlap with the patient's presentation.
- However, the severity of the **pulmonary edema** (bilateral crackles, dyspnea, low SpO2) and the **acute onset chest pain**, coupled with a history of intravenous drug abuse, make **cocaine toxicity** a more compelling diagnosis given its widely recognized acute cardiotoxicity.
Question 40: A 68-year-old man presents with urinary retention for the past week. He says his symptoms onset gradually almost immediately after being prescribed a new medication for his depression. He states that he has increased his fluid intake to try to help the issue, but this has been ineffective. He also mentions that he has been having problems with constipation and dry mouth. His past medical history is significant for major depressive disorder, diagnosed 6 months ago. The patient denies any history of smoking, alcohol consumption, or recreational drug use. He is afebrile, and his vital signs are within normal limits. A physical examination is unremarkable. A urinalysis is normal. Which of the following medications was this patient most likely prescribed for his depression?
A. Amitriptyline (Correct Answer)
B. Phenelzine
C. Mirtazapine
D. Citalopram
E. Venlafaxine
Explanation: **Amitriptyline**
- This patient's symptoms of **urinary retention**, **dry mouth**, and **constipation** are classic **anticholinergic side effects** commonly associated with tricyclic antidepressants (TCAs) like amitriptyline.
- The gradual onset and immediate appearance after starting a new antidepressant strongly point to an anticholinergic mechanism.
- TCAs block muscarinic receptors, leading to decreased parasympathetic activity and these characteristic symptoms.
*Phenelzine*
- Phenelzine is a **monoamine oxidase inhibitor (MAOI)**. While effective for depression, it is generally associated with side effects such as **orthostatic hypotension**, **insomnia**, and **hypertensive crisis** with certain food interactions, not primarily anticholinergic effects like urinary retention.
- Urinary retention is not a common or prominent side effect of MAOIs.
*Mirtazapine*
- Mirtazapine is an **alpha-2 adrenergic antagonist (NaSSA)** that primarily causes side effects like **sedation**, **increased appetite**, and **weight gain**.
- While it has some antihistaminergic activity, it is less likely to cause severe anticholinergic effects such as urinary retention compared to TCAs.
*Citalopram*
- Citalopram is a **selective serotonin reuptake inhibitor (SSRI)**. Common side effects include **gastrointestinal upset**, **sexual dysfunction**, and **insomnia**.
- SSRIs generally have a very low incidence of anticholinergic side effects; urinary retention is rare.
*Venlafaxine*
- Venlafaxine is a **serotonin-norepinephrine reuptake inhibitor (SNRI)**. Its common side effects include **nausea**, **dizziness**, **insomnia**, and **hypertension**.
- Like SSRIs, SNRIs have minimal anticholinergic activity, making urinary retention an unlikely primary side effect.
