ATI RN
Chapter 12 principles of pharmacology Questions
Question 1 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 2 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 3 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.
Question 4 of 5
The following drugs obey non-linear (dose-dependent) elimination pharmacokinetics:
Correct Answer: C
Rationale: Phenytoin (C) exhibits non-linear kinetics, with saturable hepatic metabolism (CYP2C9) causing half-life to increase at high doses (e.g., >300 mg/day). Aspirin overdose (A) and ethanol (D) are zero-order at high levels, also correct but C is chosen. Heparin (B) is complex, not purely non-linear. Ceftazidime (original E) is first-order. Non-linear kinetics, as with phenytoin, complicate dosing (e.g., toxicity risk), requiring monitoring, unlike linear drugs with predictable clearance.
Question 5 of 5
The systemic bioavailability of the following oral drugs is increased if taken in the fasting state:
Correct Answer: A
Rationale: Oxytetracycline (A) has increased bioavailability fasting, as food (e.g., calcium) chelates it, reducing absorption. Amoxicillin (B) is unaffected. Levodopa (C) competes with dietary amino acids, correct but A is chosen. Acetylsalicylic acid (D) and fluconazole (original E) are minimally impacted. Fasting enhances tetracycline uptake, critical in antibiotic therapy, avoiding food interactions that lower efficacy, a practical dosing consideration.