ATI RN
Chapter 11 principles of pharmacology Questions
Question 1 of 5
Which of the following terms best describes a co-factor that is firmly bound to an apoenzyme?
Correct Answer: B
Rationale: A prosthetic group (B) is a cofactor firmly bound to an apoenzyme (e.g., heme in hemoglobin), forming a functional holoenzyme, unlike loosely bound coenzymes (C, e.g., NADâº). Holoenzyme (A) is the complete enzyme. Transferase (D) is an enzyme class. Heteropolysaccharide (original E) is unrelated. This tight binding enhances enzyme stability and activity, critical in drug metabolism (e.g., CYP450 with heme), influencing pharmacokinetics and therapeutic outcomes.
Question 2 of 5
Which of the following salts forms an aqueous solution that is alkaline to litmus?
Correct Answer: D
Rationale: Cefazolin sodium (D) forms an alkaline solution, as its conjugate base (cefazolin anion) hydrolyzes water, raising pH (e.g., >7). Sodium chloride (A) is neutral. Benzalkonium chloride (B) and meperidine hydrochloride (C) are acidic from quaternary ammonium or protonated amines. Chlordiazepoxide hydrochloride (original E) is acidic. This basicity, from cephalosporin salts, affects compatibility in IV solutions, critical in pharmaceutical preparation and administration.
Question 3 of 5
Which of the following emissions from the decay of radionuclides is most commonly used in nuclear medicine imaging?
Correct Answer: D
Rationale: Gamma (D) emissions are most used in nuclear medicine imaging (e.g., Tc-99m in SPECT), penetrating tissue for detection without significant damage. X-rays (A) are diagnostic, not decay emissions. Beta (B) and alpha (C) are ionizing, less suitable. Positron (original E) is for PET. Gamma's high energy and low mass enable non-invasive imaging, critical for diagnosing conditions (e.g., myocardial perfusion), balancing sensitivity and safety in nuclear pharmacy.
Question 4 of 5
A 48-year-old-man with end-stage liver disease is hospitalized on the intensive care unit. Review of his blood work reveals elevated liver function tests to five times the normal rate. The patient is receiving multiple intravenous medications. Which of the following medications is likely to be therapeutic for this patient?
Correct Answer: A
Rationale: Epinephrine (A) is likely therapeutic for this patient with end-stage liver disease, as it's minimally metabolized by the liver (via COMT/MAO) and given IV, bypassing hepatic impairment. Erythromycin (B), nifedipine (C), rifampin (D), and verapamil (original E) rely heavily on hepatic metabolism (CYP3A4 or conjugation), risking accumulation with fivefold LFT elevation. Epinephrine's rapid action (e.g., for shock) and renal clearance suit ICU needs, avoiding toxicity in liver failure, where cytochrome P450 activity is compromised, a critical consideration in critically ill patients.
Question 5 of 5
A researcher is studying the bioavailability of commonly used antimuscarinics to treat irritable bowel syndrome. Medication A is administered in a $100 \mathrm{mg}$ daily dose orally and $60 \mathrm{mg}$ of the drug is absorbed from the gastrointestinal tract unchanged. Thus, the bioavailability of Medication A is
Correct Answer: B
Rationale: The bioavailability of Medication A is $60\%$ (B). Bioavailability (F) = (Amount absorbed unchanged / Dose) × 100 = (60 mg / 100 mg) × 100 = $60\%$. Options A (50\%), C (70\%), D (80\%), and E (90\%, original) miscalculate. This reflects the fraction reaching systemic circulation intact (e.g., avoiding first-pass metabolism), typical for antimuscarinics (e.g., hyoscyamine), guiding dosing for IBS, where GI absorption and hepatic metabolism determine efficacy, a key pharmacokinetic metric.