A patient with a history of binge alcohol intake presented to the emergency department with convulsions, altered sensorium, and a plasma glucose level of $45 \mathrm{mg} / \mathrm{dL}$. Which of the following treatments is needed?
Q12
What is a potential consequence of administering indomethacin beyond 36 weeks of gestation?
Q13
A 50-year-old patient with renal insufficiency was recently operated on for pyelolithotomy. Which drug is the most appropriate choice for post-operative analgesia?
Q14
Which of the following is false about pheochromocytoma?
Q15
Which of the following drugs is used for the long term management of obesity
Q16
Topiramate is used in
Q17
A 19-year-old woman with a history of poorly controlled asthma presents to her pulmonologist for a follow-up visit. She was recently hospitalized for an asthma exacerbation. It is her third hospitalization in the past five years. She currently takes inhaled salmeterol and medium-dose inhaled budesonide. Her past medical history is also notable for psoriasis. She does not smoke and does not drink alcohol. Her temperature is 98.6°F (37°C), blood pressure is 110/65 mmHg, pulse is 75/min, and respirations are 20/min. Physical examination reveals bilateral wheezes that are loudest at the bases. The patient’s physician decides to start the patient on zileuton. Which of the following is the most immediate downstream effect of initiating zileuton?
Q18
A 60-year-old man presents to the emergency department for fatigue and feeling off for the past week. He has not had any sick contacts and states that he can’t think of any potential preceding symptoms or occurrence to explain his presentation. The patient has a past medical history of diabetes, hypertension, and congestive heart failure with preserved ejection fraction. His temperature is 98°F (36.7°C), blood pressure is 125/65 mmHg, pulse is 90/min, respirations are 14/min, and oxygen saturation is 100% on room air. Laboratory values are obtained and shown below.
Hemoglobin: 12 g/dL
Hematocrit: 36%
Leukocyte count: 6,500/mm^3 with normal differential
Platelet count: 197,000/mm^3
Serum:
Na+: 147 mEq/L
Cl-: 105 mEq/L
K+: 4.1 mEq/L
HCO3-: 26 mEq/L
BUN: 21 mg/dL
Glucose: 100 mg/dL
Creatinine: 1.1 mg/dL
Ca2+: 10.1 mg/dL
AST: 12 U/L
ALT: 10 U/L
Urine:
Appearance: clear
Specific gravity: 1.003
The patient is admitted to the floor, a water deprivation test is performed, and his urine studies are repeated yet unchanged. Which of the following is the best next step in management?
Q19
A 25-year-old female with a history of childhood asthma presents to clinic complaining of a three month history of frequent, loose stools. She currently has three to four bowel movements per day, and she believes that these episodes have been getting worse and are associated with mild abdominal pain. She also endorses seeing red blood on the toilet tissue. On further questioning, she also endorses occasional palpitations over the past few months. She denies fevers, chills, headache, blurry vision, cough, shortness of breath, wheezing, nausea, or vomiting. She describes her mood as slightly irritable and she has been sleeping poorly. A review of her medical chart reveals a six pound weight loss since her visit six months ago, but she says her appetite has been normal. The patient denies any recent illness or travel. She is a non-smoker. Her only current medication is an oral contraceptive pill.
Her temperature is 37°C (98.6°F), pulse is 104/min, blood pressure is 95/65 mmHg, respirations are 16/min, and oxygen saturation is 99% on room air. On physical exam, the physician notes that her thyroid gland appears symmetrically enlarged but is non-tender to palpation. Upon auscultation there is an audible thyroid bruit. Her cranial nerve is normal and ocular exam reveals exophthalmos. Her abdomen is soft and non-tender to palpation. Deep tendon reflexes are 3+ throughout. Lab results are as follows:
Serum:
Na+: 140 mEq/L
K+: 4.1 mEq/L
Cl-: 104 mEq/L
HCO3-: 26 mEq/L
BUN: 18 mg/dL
Creatinine 0.9 mg/dL
Hemoglobin: 14.0 g/dL
Leukocyte count: 7,400/mm^3
Platelet count 450,000/mm^3
TSH & Free T4: pending
A pregnancy test is negative. The patient is started on propranolol for symptomatic relief. What is the most likely best next step in management for this patient?
Q20
A 12-year-old boy is brought to the emergency department by his mother because of progressive shortness of breath, difficulty speaking, and diffuse, colicky abdominal pain for the past 3 hours. Yesterday he underwent a tooth extraction. His father and a paternal uncle have a history of repeated hospitalizations for upper airway and orofacial swelling. The patient takes no medications. His blood pressure is 112/62 mm Hg. Examination shows edematous swelling of the lips, tongue, arms, and legs; there is no rash. Administration of a drug targeting which of the following mechanisms of action is most appropriate for this patient?
Autonomic/CV Drugs US Medical PG Practice Questions and MCQs
Question 11: A patient with a history of binge alcohol intake presented to the emergency department with convulsions, altered sensorium, and a plasma glucose level of $45 \mathrm{mg} / \mathrm{dL}$. Which of the following treatments is needed?
A. Thiamine
B. $25 \% $ Dextrose
C. Thiamine followed by Dextrose (Correct Answer)
D. Fomepizole
E. Glucagon
Explanation: ***Thiamine followed by Dextrose***
- In patients with **alcoholism** and suspected **hypoglycemia**, thiamine should always be administered before or concurrently with dextrose to prevent **Wernicke encephalopathy**.
- Dextrose alone can precipitate or worsen Wernicke encephalopathy in **thiamine-deficient** individuals by increasing carbohydrate metabolism, thereby depleting residual thiamine.
*Thiamine*
- While **thiamine** is crucial for patients with chronic alcohol intake, administering it alone will not immediately resolve the **hypoglycemia** and associated neurological symptoms like convulsions and altered sensorium.
- Thiamine is essential to prevent complications like **Wernicke-Korsakoff syndrome**, but the immediate life-threatening issue is the low blood glucose.
*25% Dextrose*
- Administering **dextrose** alone to an **alcohol-dependent** patient is risky because it can precipitate or worsen **Wernicke's encephalopathy** by increasing glucose metabolism without adequate thiamine.
- While dextrose will correct the **hypoglycemia**, its administration without prior thiamine is contraindicated in this patient population.
*Glucagon*
- **Glucagon** works by mobilizing hepatic glycogen stores to raise blood glucose levels.
- In patients with **chronic alcohol intake**, hepatic glycogen stores are often **depleted**, making glucagon ineffective.
- Additionally, glucagon has a **slower onset** compared to intravenous dextrose, making it unsuitable for this emergency situation with convulsions and altered sensorium.
*Fomepizole*
- **Fomepizole** is an antidote used in cases of **methanol** or **ethylene glycol poisoning** to inhibit alcohol dehydrogenase.
- It is not indicated for treating **alcohol withdrawal**, **hypoglycemia**, or related complications in patients with binge alcohol intake.
Question 12: What is a potential consequence of administering indomethacin beyond 36 weeks of gestation?
A. Teratogenic
B. No effect
C. Premature closure of the patent ductus arteriosus (PDA) (Correct Answer)
D. Still birth
E. Oligohydramnios
Explanation: ***Premature closure of the patent ductus arteriosus (PDA)***
- **Indomethacin**, a non-steroidal anti-inflammatory drug (NSAID), inhibits **prostaglandin synthesis**, which is crucial for maintaining PDA patency in utero.
- **Premature closure of the PDA** beyond 36 weeks of gestation can lead to **pulmonary hypertension** and **fetal heart failure**, as blood flow through the fetal circulation would be significantly altered.
- This is the **most serious cardiovascular complication** of indomethacin use in late pregnancy.
*Teratogenic*
- While some medications can be teratogenic (cause birth defects), **indomethacin** is not generally considered to have a significant teratogenic risk when used in the third trimester.
- The primary concern with NSAID use in late pregnancy is related to their effects on fetal circulation and renal function, not structural anomalies.
*No effect*
- This statement is incorrect because **indomethacin** has well-documented and significant effects on fetal circulation, particularly on the **ductus arteriosus**, especially in the third trimester.
- Its mechanism of action profoundly impacts the maintenance of the fetal circulatory shunts.
*Still birth*
- While **indomethacin** use in late pregnancy can lead to serious fetal complications such as **pulmonary hypertension** and **renal dysfunction**, leading to **fetal compromise**, it does not directly or exclusively cause stillbirth.
- The specific and most direct consequence on the cardiovascular system is the premature closure of the PDA.
*Oligohydramnios*
- While **oligohydramnios** (decreased amniotic fluid) can occur with prolonged NSAID use due to **decreased fetal urine output** from renal effects, this is not the primary concern beyond 36 weeks.
- The more immediate and serious risk is **premature PDA closure** with its cardiovascular consequences.
Question 13: A 50-year-old patient with renal insufficiency was recently operated on for pyelolithotomy. Which drug is the most appropriate choice for post-operative analgesia?
A. Diclofenac sodium
B. Naproxen
C. Indomethacin
D. Acetaminophen (Correct Answer)
E. Ketorolac
Explanation: ***Acetaminophen***
- **Acetaminophen** is primarily metabolized in the liver, with minimal renal excretion, making it a safer option for patients with **renal insufficiency**.
- It provides effective **analgesia** without the adverse renal effects associated with NSAIDs.
*Diclofenac sodium*
- **Diclofenac** is a non-steroidal anti-inflammatory drug (**NSAID**) that can impair renal function, especially in patients with pre-existing **renal insufficiency**, by inhibiting prostaglandin synthesis.
- Its use can lead to further **kidney damage** or exacerbate existing renal impairment.
*Naproxen*
- **Naproxen** is an **NSAID** that carries a significant risk of causing acute kidney injury in patients with **compromised renal function**.
- It reduces renal blood flow and glomerular filtration rate, making it unsuitable for this patient.
*Indomethacin*
- **Indomethacin** is a potent **NSAID** known for its adverse renal effects, including acute renal failure.
- It should be avoided in patients with **renal insufficiency** due to its potential to further decline kidney function.
*Ketorolac*
- **Ketorolac** is a potent **NSAID** commonly used for post-operative pain but is **contraindicated** in patients with renal insufficiency.
- It has significant nephrotoxic potential and can cause acute renal failure, especially in patients with pre-existing kidney disease.
Question 14: Which of the following is false about pheochromocytoma?
A. Surgery is the treatment of choice
B. VMA (vanillylmandelic acid) is a diagnostic test
C. Propranolol is the preferred drug for hypertension control (Correct Answer)
D. Catecholamines are a diagnostic test
E. Most pheochromocytomas are benign
Explanation: ***Propranolol is the preferred drug for hypertension control***
- Propranolol, a **beta-blocker**, is generally contraindicated as monotherapy in pheochromocytoma because blocking beta-receptors unopposed can lead to a **hypertensive crisis** due to unopposed alpha-adrenergic vasoconstriction.
- **Alpha-blockers** (e.g., phenoxybenzamine) are the first-line agents for hypertension control, followed by beta-blockers once adequate alpha-blockade is established.
*Surgery is the treatment of choice*
- **Surgical resection** of the tumor is indeed the definitive treatment for pheochromocytoma once the patient has been appropriately prepared with alpha-blockade.
- This approach aims to remove the source of excessive catecholamine production and resolve the associated symptoms.
*VMA (vanillylmandelic acid) is a diagnostic test*
- **VMA** is a metabolic breakdown product of catecholamines, and its measurement in a **24-hour urine collection** is a long-standing method for diagnosing pheochromocytoma.
- Elevated VMA levels indicate overproduction of catecholamines, which is characteristic of the tumor.
*Catecholamines are a diagnostic test*
- Measuring **plasma free metanephrines** and **24-hour urinary fractionated metanephrines** (which are methylated metabolites of catecholamines) are highly sensitive and specific diagnostic tests for pheochromocytoma.
- Elevated levels confirm the excessive secretion of these hormones by the tumor.
*Most pheochromocytomas are benign*
- Approximately **90% of pheochromocytomas are benign**, with only about 10% being malignant.
- The **"rule of 10s"** is a helpful mnemonic: 10% bilateral, 10% extra-adrenal, 10% malignant, 10% familial, and 10% occur in children.
Question 15: Which of the following drugs is used for the long term management of obesity
A. Fenfluramine
B. Sibutramine
C. Liraglutide (Correct Answer)
D. Metformin
E. Orlistat
Explanation: ***Liraglutide***
- **Liraglutide** is a **GLP-1 receptor agonist** approved for **long-term weight management** in adults with obesity or overweight with comorbidities.
- It works by **delaying gastric emptying**, increasing satiety, and reducing appetite, leading to sustained weight loss.
*Fenfluramine*
- **Fenfluramine** was an **anorectic drug** that was withdrawn from the market due to its association with **pulmonary hypertension** and **cardiac valvulopathy**.
- It is **not used** for the long-term management of obesity due to severe cardiovascular side effects.
*Sibutramine*
- **Sibutramine** is a **serotonin-norepinephrine reuptake inhibitor** previously used for weight loss, but it was withdrawn due to increased risk of **cardiovascular events** such as heart attack and stroke.
- It is **not recommended** for long-term obesity management due to its significant cardiovascular risks.
*Orlistat*
- **Orlistat** is a **pancreatic lipase inhibitor** that is approved for long-term obesity management but works by **reducing fat absorption** in the gastrointestinal tract.
- While approved for long-term use, it is **less preferred** than GLP-1 agonists due to gastrointestinal side effects (steatorrhea, fecal incontinence) and lower efficacy in weight reduction compared to newer agents like liraglutide.
*Metformin*
- **Metformin** is primarily an **antidiabetic drug** used for type 2 diabetes and sometimes for polycystic ovary syndrome (PCOS).
- While it may cause modest weight loss as a side effect, it is **not approved or indicated** as a primary drug for the long-term management of obesity in individuals without diabetes.
Question 16: Topiramate is used in
A. 1st Line Treatment of ADHD
B. Treatment of Acute Migraine
C. Management of Seizures in Lennox-Gastaut Syndrome (Correct Answer)
D. Treatment of Dementia
E. Treatment of Bipolar Disorder
Explanation: ***Management of Seizures in Lennox-Gastaut Syndrome***
- Topiramate is an **antiepileptic drug** approved for the treatment of **partial-onset seizures**, tonic-clonic seizures, and seizures associated with **Lennox-Gastaut syndrome**.
- Its multiple mechanisms of action, including blocking **voltage-gated sodium channels**, enhancing **GABAergic activity**, and antagonizing **AMPA/kainate glutamate receptors**, make it effective in managing complex seizure disorders.
- This is a **primary FDA-approved indication** for topiramate.
*1st Line Treatment of ADHD*
- First-line treatments for ADHD typically involve **stimulants** like methylphenidate or amphetamines, or non-stimulants such as atomoxetine.
- While topiramate can have cognitive side effects like "brain fog," it is **not considered a primary treatment** for ADHD.
*Treatment of Acute Migraine*
- Topiramate is used for **migraine prophylaxis (prevention)**, not for the acute treatment of a migraine attack.
- Acute migraine treatments include triptans, NSAIDs, and CGRP inhibitors.
- The key distinction is **prophylaxis vs. acute treatment**.
*Treatment of Dementia*
- There is **no evidence** that topiramate is effective in treating dementia or improving cognitive function in patients with dementia.
- Current treatments for dementia often involve cholinesterase inhibitors or NMDA receptor antagonists.
*Treatment of Bipolar Disorder*
- While topiramate has been studied in bipolar disorder, it is **not FDA-approved** for this indication.
- Standard mood stabilizers include lithium, valproate, carbamazepine, and atypical antipsychotics.
- Topiramate lacks sufficient evidence for efficacy in bipolar disorder management.
Question 17: A 19-year-old woman with a history of poorly controlled asthma presents to her pulmonologist for a follow-up visit. She was recently hospitalized for an asthma exacerbation. It is her third hospitalization in the past five years. She currently takes inhaled salmeterol and medium-dose inhaled budesonide. Her past medical history is also notable for psoriasis. She does not smoke and does not drink alcohol. Her temperature is 98.6°F (37°C), blood pressure is 110/65 mmHg, pulse is 75/min, and respirations are 20/min. Physical examination reveals bilateral wheezes that are loudest at the bases. The patient’s physician decides to start the patient on zileuton. Which of the following is the most immediate downstream effect of initiating zileuton?
A. Decreased signaling via the leukotriene receptor
B. Decreased signaling via the muscarinic receptor
C. Decreased mast cell degranulation
D. Decreased production of leukotrienes (Correct Answer)
E. Decreased IgE-mediated pro-inflammatory activity
Explanation: ***Decreased production of leukotrienes***
- **Zileuton** is a **5-lipoxygenase inhibitor**. This enzyme is crucial for the synthesis of **leukotrienes** from arachidonic acid.
- By inhibiting 5-lipoxygenase, zileuton directly reduces the overall production of all types of leukotrienes, including LTB4, LTC4, LTD4, and LTE4.
*Decreased signaling via the leukotriene receptor*
- This describes the mechanism of action for **leukotriene receptor antagonists** (LTRAs) like montelukast and zafirlukast, which block leukotriene receptors.
- While zileuton ultimately reduces leukotriene effects, its direct and immediate action is on leukotriene synthesis, not receptor blockade.
*Decreased signaling via the muscarinic receptor*
- This is the mechanism of action for **anticholinergic bronchodilators** (e.g., ipratropium, tiotropium), which block the action of acetylcholine at muscarinic receptors.
- Zileuton does not act on the muscarinic receptor system.
*Decreased mast cell degranulation*
- This is the primary action of **mast cell stabilizers** like cromolyn and nedocromil, which prevent the release of inflammatory mediators from mast cells.
- While leukotrienes are involved in inflammation, zileuton's direct action is not on preventing mast cell degranulation itself but rather on blocking a pathway downstream from initial triggers.
*Decreased IgE-mediated pro-inflammatory activity*
- This describes the mechanism of action for **omalizumab**, a monoclonal antibody that targets IgE, preventing its binding to mast cells and basophils.
- Zileuton acts on the leukotriene synthesis pathway, independent of IgE-mediated processes.
Question 18: A 60-year-old man presents to the emergency department for fatigue and feeling off for the past week. He has not had any sick contacts and states that he can’t think of any potential preceding symptoms or occurrence to explain his presentation. The patient has a past medical history of diabetes, hypertension, and congestive heart failure with preserved ejection fraction. His temperature is 98°F (36.7°C), blood pressure is 125/65 mmHg, pulse is 90/min, respirations are 14/min, and oxygen saturation is 100% on room air. Laboratory values are obtained and shown below.
Hemoglobin: 12 g/dL
Hematocrit: 36%
Leukocyte count: 6,500/mm^3 with normal differential
Platelet count: 197,000/mm^3
Serum:
Na+: 147 mEq/L
Cl-: 105 mEq/L
K+: 4.1 mEq/L
HCO3-: 26 mEq/L
BUN: 21 mg/dL
Glucose: 100 mg/dL
Creatinine: 1.1 mg/dL
Ca2+: 10.1 mg/dL
AST: 12 U/L
ALT: 10 U/L
Urine:
Appearance: clear
Specific gravity: 1.003
The patient is admitted to the floor, a water deprivation test is performed, and his urine studies are repeated yet unchanged. Which of the following is the best next step in management?
A. Administer desmopressin (Correct Answer)
B. Administer hypotonic fluids
C. Perform a head CT
D. Administer demeclocycline
E. Obtain a serum renin:aldosterone ratio
Explanation: ***Administer desmopressin***
- The patient's presentation with **fatigue**, **hypernatremia**, **dilute urine** (specific gravity 1.003), and unchanged urine studies after a **water deprivation test** is characteristic of **central diabetes insipidus**.
- **Desmopressin (dDAVP)** is a synthetic analog of **ADH** and is the primary treatment for central diabetes insipidus, as it will **replace the missing ADH** and allow the kidneys to concentrate urine.
*Administer hypotonic fluids*
- Administering hypotonic fluids would be indicated for **hypernatremia** due to **dehydration**, but the underlying issue here is the **inability to retain water** due to **ADH deficiency**, not solely insufficient fluid intake.
- While necessary to correct the hypernatremia, without addressing the underlying ADH deficiency, the patient would continue to excrete large volumes of dilute urine, leading to persistent hypernatremia or requiring continuous, large volumes of hypotonic fluids.
*Perform a head CT*
- A head CT could be considered later to investigate the **cause of central diabetes insipidus** (e.g., tumor, trauma, inflammation), but the immediate priority is to **treat the ADH deficiency** to prevent severe dehydration and neurological complications from hypernatremia.
- While diagnosing the underlying cause is important, it is not the best *next step in management* for the acute symptoms and electrolyte imbalance.
*Administer demeclocycline*
- **Demeclocycline** is a drug used to treat the **syndrome of inappropriate antidiuretic hormone (SIADH)**, which is characterized by **hyponatremia** and **concentrated urine** due to excessive ADH.
- This patient presents with **hypernatremia** and **dilute urine**, which is the exact opposite of SIADH, making demeclocycline an inappropriate treatment.
*Obtain a serum renin:aldosterone ratio*
- A serum **renin:aldosterone ratio** is used to evaluate for primary **hyperaldosteronism** (Conn's syndrome), which is characterized by **hypertension**, **hypokalemia**, and **metabolic alkalosis**.
- This patient has **hypernatremia** and a normal potassium level, with no clear indication of hyperaldosteronism.
Question 19: A 25-year-old female with a history of childhood asthma presents to clinic complaining of a three month history of frequent, loose stools. She currently has three to four bowel movements per day, and she believes that these episodes have been getting worse and are associated with mild abdominal pain. She also endorses seeing red blood on the toilet tissue. On further questioning, she also endorses occasional palpitations over the past few months. She denies fevers, chills, headache, blurry vision, cough, shortness of breath, wheezing, nausea, or vomiting. She describes her mood as slightly irritable and she has been sleeping poorly. A review of her medical chart reveals a six pound weight loss since her visit six months ago, but she says her appetite has been normal. The patient denies any recent illness or travel. She is a non-smoker. Her only current medication is an oral contraceptive pill.
Her temperature is 37°C (98.6°F), pulse is 104/min, blood pressure is 95/65 mmHg, respirations are 16/min, and oxygen saturation is 99% on room air. On physical exam, the physician notes that her thyroid gland appears symmetrically enlarged but is non-tender to palpation. Upon auscultation there is an audible thyroid bruit. Her cranial nerve is normal and ocular exam reveals exophthalmos. Her abdomen is soft and non-tender to palpation. Deep tendon reflexes are 3+ throughout. Lab results are as follows:
Serum:
Na+: 140 mEq/L
K+: 4.1 mEq/L
Cl-: 104 mEq/L
HCO3-: 26 mEq/L
BUN: 18 mg/dL
Creatinine 0.9 mg/dL
Hemoglobin: 14.0 g/dL
Leukocyte count: 7,400/mm^3
Platelet count 450,000/mm^3
TSH & Free T4: pending
A pregnancy test is negative. The patient is started on propranolol for symptomatic relief. What is the most likely best next step in management for this patient?
A. Thyroid scintigraphy with I-123
B. Surgical thyroidectomy
C. IV hydrocortisone
D. Adalimumab
E. Methimazole (Correct Answer)
Explanation: ***Methimazole***
- The patient's symptoms (tachycardia, weight loss despite normal appetite, irritability, insomnia, diarrhea, exophthalmos, goiter with bruit, hyperreflexia) are classic for **hyperthyroidism**, most likely **Graves' disease**.
- **Methimazole** is an antithyroid drug that inhibits thyroid hormone synthesis and is a primary treatment for hyperthyroidism.
*Thyroid scintigraphy with I-123*
- While thyroid scintigraphy is useful for differentiating causes of hyperthyroidism, it is typically performed **after initial laboratory confirmation** of hyperthyroidism (TSH and T4 levels) to guide long-term treatment.
- Given the strong clinical picture, immediate treatment to control symptoms (propranolol) and reduce hormone synthesis (methimazole) is a more pressing next step.
*Surgical thyroidectomy*
- **Thyroidectomy** is a definitive treatment for hyperthyroidism but is usually reserved for cases that fail medical therapy, have very large goiters, or suspicion of malignancy.
- It also requires the patient to be **euthyroid** before surgery to minimize operative risks.
*IV hydrocortisone*
- **IV hydrocortisone** is used for the treatment of **thyroid storm**, a severe, life-threatening manifestation of hyperthyroidism, or in cases of adrenal crisis.
- While the patient is symptomatic, her vital signs and lack of severe multi-organ dysfunction do not suggest thyroid storm.
*Adalimumab*
- **Adalimumab** is a TNF-alpha inhibitor used to treat autoimmune conditions like inflammatory bowel disease (Crohn's disease, ulcerative colitis), rheumatoid arthritis, or psoriasis.
- Although the patient has GI symptoms, **inflammatory bowel disease** is less likely given the constellation of other symptoms pointing to hyperthyroidism, and adalimumab is not a treatment for thyroid disease.
Question 20: A 12-year-old boy is brought to the emergency department by his mother because of progressive shortness of breath, difficulty speaking, and diffuse, colicky abdominal pain for the past 3 hours. Yesterday he underwent a tooth extraction. His father and a paternal uncle have a history of repeated hospitalizations for upper airway and orofacial swelling. The patient takes no medications. His blood pressure is 112/62 mm Hg. Examination shows edematous swelling of the lips, tongue, arms, and legs; there is no rash. Administration of a drug targeting which of the following mechanisms of action is most appropriate for this patient?
A. Antagonist at bradykinin receptor (Correct Answer)
B. Antagonist at histamine receptor
C. Agonist at glucocorticoid receptor
D. Agonist at androgen receptor
E. Inhibitor of angiotensin-converting enzyme
Explanation: ***Antagonist at bradykinin receptor***
- The patient's symptoms (laryngeal edema, abdominal pain, diffuse limb swelling without rash), family history (recurrent angioedema), and recent dental procedure (a known trigger) are highly suggestive of **hereditary angioedema (HAE)**.
- HAE is caused by a deficiency or dysfunction of **C1 esterase inhibitor**, leading to uncontrolled activation of the **kallikrein-kinin system** and excessive production of **bradykinin**, which mediates the edema. Treatment involves targeting bradykinin directly (e.g., icatibant, a bradykinin B2 receptor antagonist) or replacing C1 esterase inhibitor.
*Antagonist at histamine receptor*
- **Antihistamines** are effective for histamine-mediated angioedema, which typically presents with **urticaria (hives)** and pruritus.
- The absence of a rash and lack of pruritus in this patient, along with the specific triggers and family history, make histamine-mediated angioedema (e.g., allergic angioedema) unlikely.
*Agonist at glucocorticoid receptor*
- **Glucocorticoids** (corticosteroids) are effective in treating inflammatory conditions and allergic reactions, often used for histamine-mediated angioedema.
- They are **ineffective** in acute attacks of hereditary angioedema because bradykinin-mediated pathways do not primarily involve inflammation responsive to corticosteroids.
*Agonist at androgen receptor*
- **Androgens** (e.g., danazol, stanozolol) are used for the **long-term prophylaxis** of hereditary angioedema by increasing C1 esterase inhibitor production.
- They are **not appropriate for acute treatment** due to their slow onset of action and are contraindicated in prepubertal children due to side effects.
*Inhibitor of angiotensin-converting enzyme*
- **ACE inhibitors** can cause acquired angioedema by **inhibiting bradykinin degradation**, leading to its accumulation.
- However, the patient is currently on no medications, making **ACE inhibitor-induced angioedema unlikely**, and stopping the ACE inhibitor (if he were on one) would be crucial, but an acute specific treatment targeting bradykinin is still needed.