ATI RN
Chapter 12 principles of pharmacology Questions
Question 1 of 5
A 40-year-old man is brought to the emergency department after suffering a cardiac arrest while in a shopping mall. His blood pressure is $70 / 40 \mathrm{~mm} \mathrm{Hg}$ and his pulse is 40 beats/minute. He is given a dose of intravenous epinephrine. Which of the following reactions is necessary to induce a biologic response of increased heart rate?
Correct Answer: B
Rationale: Drug-receptor complex formation (B) is necessary for epinephrine to increase heart rate. Epinephrine binds $\beta_1$-adrenergic receptors on cardiac myocytes, activating Gs proteins, increasing cAMP, and enhancing contractility/chronotropy. Detrusor contraction (A) is bladder-related. Hepatic oxidation (C) is metabolism, not action. Renal contraction (D) or splanchnic stimulation (original E) are unrelated. This receptor interaction, critical in cardiac arrest, drives rapid hemodynamic response, a pharmacodynamic cornerstone for catecholamines in emergencies.
Question 2 of 5
An 80-year-old male nursing home resident is hospitalized on a morphine drip to control pain for his terminal metastatic pancreatic cancer. Morphine undergoes phase I and phase II metabolism in the liver as well as being metabolized by other enzymes. Some of these metabolic reactions decrease with age. Which of the following metabolic reactions is likely still intact in this patient?
Correct Answer: A
Rationale: Glucuronidation (A) is likely intact in this elderly patient. This phase II reaction, conjugating morphine to morphine-6-glucuronide via UGT enzymes, declines less with age than phase I reactions (e.g., CYP450 oxidation), which slow significantly. Hydrolysis (B), oxidation (C), reduction (D), and unmasking (original E) are phase I, more affected by aging liver function. Morphine's active metabolite from glucuronidation retains potency, critical in pain control, with preserved conjugation ensuring clearance despite age-related hepatic decline, a key consideration in geriatric pharmacology.
Question 3 of 5
A 44-year-old black male is brought to the emergency department with 6 h of worsening lethargy and confusion. Past medical history is significant for easy bruising, 3 months of bone pain, and frequent pneumococcal infections. Labs were ordered, revealing serum calcium of $17 \mathrm{mg} / \mathrm{dL}$ (normal: 9.0 to $10.5 \mathrm{mg} / \mathrm{dL}$ ). To rapidly lower his serum calcium, you administer calcitonin. However, calcitonin alone is insufficient because it is known to rapidly and suddenly lose its effectiveness within 2 to 3 days of repeated dosing. For this reason, a bisphosphonate, which take 2 to 3 days to become effective, is added simultaneously. What is the term for the rapid decrease in response to calcitonin?
Correct Answer: C
Rationale: Tachyphylaxis (C) is the rapid decrease in response to calcitonin after repeated dosing (2-3 days), likely from receptor downregulation or desensitization, common with peptide hormones. Anaphylaxis (A) is allergic. Prophylaxis (B) is prevention. Tolerance (D) is slower, chronic. Calcitonin's short-term calcium drop (hypercalcemia, 17 mg/dL) pairs with bisphosphonates' delayed onset, a strategic combo in multiple myeloma (suggested by history), highlighting tachyphylaxis's impact on acute management.
Question 4 of 5
A 52-year-old woman with multiple endocrine neoplasia syndromes has a large pancreatic tumor and bilateral adrenal tumors. She is hospitalized on the medicine service. The tumor is considered inoperable. Her blood pressure is $180 / 100 \mathrm{~mm} \mathrm{Hg}$. In addition to intravenous fluids, this patient may benefit from which of the following interventions?
Correct Answer: D
Rationale: Phentolamine IV (D) benefits this patient with likely pheochromocytoma (adrenal tumors, hypertension 180/100), an $\alpha$-blocker reversing catecholamine-induced vasoconstriction rapidly, critical in MEN syndromes. Oral analgesics (A) and transdermal (B) address pain, not BP. Phenoxybenzamine (C) is oral, slower. Tolterodine (original E) is irrelevant. Phentolamine's IV onset controls acute hypertensive crises, stabilizing for surgery or palliation, a key intervention in endocrine emergencies.
Question 5 of 5
The following drugs cause their primary pharmacodynamic effect via non-receptor mediated mechanisms:
Correct Answer: B
Rationale: Mannitol (B) acts via osmotic diuresis, increasing urine volume without receptor binding, used in cerebral edema. Magnesium trisilicate (A) neutralizes gastric acid chemically, also correct but B is selected. Methotrexate (C) inhibits DHFR, an enzyme. Dimercaprol (D) chelates metals, non-receptor mediated too. Sumatriptan (original E) is a 5-HTâ‚ agonist. Non-receptor mechanisms, like mannitol's osmotic effect, bypass traditional signaling, critical in emergencies for rapid, physical action, contrasting receptor-based drugs in pharmacology.