ATI RN
Chapter 2 pharmacologic principles Questions
Question 1 of 5
Flurazepam has pKa of 8.2. What percentage of flurazepam will be ionized at a urine pH of 5.2 ?
Correct Answer: B
Rationale: Flurazepam (pKa 8.2), a weak base, is 1% ionized at urine pH 5.2 (B). Henderson-Hasselbalch: pH = pKa + log([B]/[BHâº]); 5.2 = 8.2 + log([B]/[BHâº]), log([B]/[BHâº]) = -3, [B]/[BHâº] = 0.001, so BH⺠(ionized) is 99.9/100.9 ≈ 99%, un-ionized ~1%. Options A (0.1%), C (50%), and D (99%) miscalculate. Option E (original, 99.9%) inverts. This low ionization favors reabsorption, slowing excretion, relevant in benzodiazepine pharmacokinetics and overdose management.
Question 2 of 5
A hospitalized patient with systemic candidiasis is receiving intravenous antifungal medications. He also has hepatic and renal insufficiency. Which of the following drug administration schemes would allow for the most steady state amount of drug in the body over a 2-week hospitalization period where medication administration will be necessary?
Correct Answer: A
Rationale: Continuous IV infusion (A) provides the most steady-state drug levels over 2 weeks in a patient with systemic candidiasis and hepatic/renal insufficiency. It delivers a constant rate, compensating for impaired clearance (e.g., antifungals like amphotericin), avoiding peaks/troughs of intermittent dosing (B, C, D, E original). Weekly (B) or twice-weekly (E) injections risk subtherapeutic gaps; daily (C) or twice-daily (D) cause fluctuations. Steady-state maintenance is critical in severe infections with compromised metabolism/excretion, ensuring consistent therapeutic levels, reducing toxicity, and optimizing outcomes in critical care.
Question 3 of 5
A 59-year-old female with diabetes presents to her primary care physician for routine follow-up. Her current medications include insulin. Her fasting blood sugars are in the range of 80 to $120 \mathrm{mg} / \mathrm{dL}$. The intracellular effects of this medication are likely caused by which of the following mechanisms of action?
Correct Answer: C
Rationale: Insulin's intracellular effects occur via protein phosphorylation (C). Binding its tyrosine kinase receptor, insulin triggers autophosphorylation, activating cascades (e.g., PI3K-Akt) that phosphorylate proteins, promoting glucose uptake (GLUT4 translocation). Ionic changes (A) and membrane potential (B) are ion channel effects. Protein and receptor phosphorylation (D) overcomplicates; receptor phosphorylation initiates, but cellular effects are downstream. Receptor destruction (original E) is false. This mechanism ensures glycemic control (80-120 mg/dL), critical in diabetes management, distinguishing insulin from ionotropic drugs.
Question 4 of 5
A 61-year-old man is taking over-the-counter pseudoephedrine for cold and flulike symptoms. Over the course of the next few days, he experiences improvement in his rhinitis but should be concerned about the possibility of which of the following problems?
Correct Answer: D
Rationale: Urinary retention (D) is a concern with pseudoephedrine, an $\alpha_1$-agonist causing urethral sphincter contraction, impairing bladder emptying, especially in older men (e.g., with BPH). Iris contraction (A) is muscarinic, not adrenergic. Bronchoconstriction (B) contradicts its $\beta_2$-mediated dilation. Erectile improvement (C) isn't typical; $\alpha$-effects may worsen it. Thinning secretions (original E) occurs but isn't problematic. This $\alpha$-adrenergic side effect, critical in the elderly, requires caution, balancing rhinitis relief with urinary risks.
Question 5 of 5
A 34-year-old female insists on drinking a cup of grapefruit juice every morning for 'body cleansing.' Grapefruit juice is known to interfere with the cytochrome P450 system, disrupting levels of certain drugs. The cytochrome P450 system includes dozens of enzymes. Which is the most abundant CYP enzyme in human livers?
Correct Answer: E
Rationale: CYP3A4 (E, original) is the most abundant CYP enzyme in human livers (~30-40\% of total), metabolizing many drugs (e.g., statins). Grapefruit juice inhibits it, raising drug levels (e.g., felodipine). CYP1A2 (A) handles caffeine, CYP2A6 (B) nicotine, CYP2D6 (C) antidepressants, and CYP2E1 (D) ethanol:all less abundant. CYP3A4's dominance and intestinal presence amplify juice interactions, critical in pharmacokinetics, necessitating caution with co-administered substrates.