ATI RN
Chapter 26 principles of pharmacology Questions
Question 1 of 5
A 79-year-old man with end-stage Alzheimer's disease and dysphagia is taking multiple medications. Physical examination reveals xerostomia and a limited gag reflex. Which of the following routes of medication administration would provide the lowest serum drug concentration?
Correct Answer: A
Rationale: Enteral (A) administration would provide the lowest serum drug concentration in this patient due to the challenges posed by his dysphagia and limited gag reflex, which impair swallowing and gastrointestinal absorption. Enteral routes (e.g., oral) rely on GI uptake, which can be erratic or reduced in such conditions, further complicated by xerostomia reducing dissolution. Intramuscular (B) and intravenous (D) routes deliver drugs directly into systemic circulation, yielding higher concentrations. Intrathecal (C) targets the CSF, not serum, but still achieves systemic levels. Transdermal (original E) offers steady absorption but higher serum levels than enteral in this context. Given his swallowing difficulties, enteral drugs face significant barriers (e.g., incomplete absorption, first-pass metabolism), making it the least effective for systemic delivery, critical in managing polypharmacy in Alzheimer's patients.
Question 2 of 5
The therapeutic index of a drug is the ratio of the dose that produces toxicity to the dose that produces an efficacious response. By this definition, which of the following medications has the largest therapeutic index?
Correct Answer: A
Rationale: Diazepam (A) has the largest therapeutic index (TI = TD50/ED50), often >100, as its toxic dose (e.g., respiratory depression) far exceeds its anxiolytic dose, making it relatively safe. Digoxin (B), gentamicin (C), lithium (D), and theophylline (original E) have narrow TIs (<10), with toxicity (e.g., arrhythmias, ototoxicity, tremors, bronchospasm) near therapeutic doses. Diazepam's wide TI reflects its forgiving dose-response, critical in anxiolytics vs. drugs requiring tight monitoring, a key safety metric in pharmacology.
Question 3 of 5
A 22-year-old woman who is afraid of running into her former boyfriend actually meets him unexpectedly in a shopping mall. Her fears are because their former relationship was marked by physical and mental abuse. Memories of him are met with increased anxiety and fear. Which of the following physiologic responses would this woman be expected to exhibit at this time of seeing this man?
Correct Answer: C
Rationale: Hypertension (C) is expected due to sympathetic activation from fear and anxiety, releasing catecholamines (e.g., epinephrine), increasing heart rate and vasoconstriction. Bradycardia (A) opposes this fight-or-flight response. Diarrhea (B) may occur later but isn't immediate. Sweating (D) accompanies but is secondary. Tracheal deviation (original E) is unrelated. This acute stress response, mediated by the HPA axis and sympathetics, elevates BP, a physiologic adaptation to perceived threat, relevant in anxiety pharmacology.
Question 4 of 5
Researchers interested in studying a certain cytochrome P450 enzyme wish to isolate the enzyme of interest from the many other proteins in the cells. One of their initial steps is to lyse the cells and isolate the organelle which carries the enzyme they want to study. Which organelle will they isolate to find CYP enzymes?
Correct Answer: E
Rationale: Smooth endoplasmic reticulum (E, original) houses CYP enzymes, where phase I metabolism (e.g., oxidation) occurs in hepatocytes. Golgi (A) processes proteins, lysosomes (B) degrade waste, mitochondria (C) produce energy, and peroxisomes (D) handle fatty acids. SER's microsomal fraction, rich in CYPs (e.g., CYP3A4), is isolated via centrifugation, critical for studying drug metabolism, enzyme induction (e.g., by rifampin), and interactions, a foundational step in pharmacology research.
Question 5 of 5
A 24-year-old woman presents to her primary care physician complaining of feeling sleepy all the time. She has a history of hay fever since the age of 9 years. She is currently taking an antihistamine but cannot remember the name. She says it controls her hay fever symptoms well. You suspect that her medication is causing her to feel sleepy. First generation antihistamines can cause drowsiness because they cross the blood-brain barrier and act on which receptor?
Correct Answer: A
Rationale: First-generation antihistamines (e.g., diphenhydramine) cause drowsiness by crossing the BBB and blocking H₠receptors (A) in the CNS, reducing alertness. H₂ (B) regulates gastric acid. H₃ (C) modulates histamine release. H₄ (D) affects immunity. Their lipid solubility enables CNS penetration, unlike second-generation (e.g., cetirizine), critical in hay fever management, where sedation is a trade-off for symptom relief, guiding drug choice.