ATI RN
Chapter 26 principles of pharmacology Questions
Question 1 of 5
The plasma clearance of a drug:
Correct Answer: A
Rationale: Plasma clearance (A) is the volume of plasma cleared of drug per unit time (e.g., mL/min), reflecting total elimination (hepatic, renal). Option B is true (CL = dose rate / Css), but A defines it. Option C is correct but less definitional. Option D is false; hepatic metabolism is included. Option E (original) about renal function is true but secondary. Clearance's volume-based metric, critical in dosing (e.g., gentamicin), integrates all elimination pathways, offering a comprehensive efficiency measure over half-life alone.
Question 2 of 5
The following drugs are effectively administered by the rectal route to produce their systemic effect:
Correct Answer: C
Rationale: Metronidazole (C) is effective rectally for systemic effects (e.g., anaerobic infections), partially avoiding first-pass metabolism. Indometacin (A) is correct too but C is chosen. Sulfasalazine (B) acts locally. Glycerin (D) is local (laxative). Diazepam (original E) is systemic via rectum. Rectal administration, useful in nausea or unconsciousness, enhances metronidazole's bioavailability, a key alternative route in pharmacology.
Question 3 of 5
The following agents induce hepatic CYP450:
Correct Answer: A
Rationale: Rifampicin (A) induces CYP450 (e.g., CYP3A4), increasing metabolism of substrates (e.g., warfarin), reducing their levels. Carbamazepine (B), St John's wort (C), and phenobarbital (D) are inducers too, correct but A is chosen. Penicillin (original E) is not. Induction, critical in drug interactions, accelerates clearance, necessitating dose adjustments, a key pharmacokinetic principle in polypharmacy.
Question 4 of 5
The following drugs must be avoided in severe renal failure (glomerular filtration rate (GFR) <10 mL/min):
Correct Answer: D
Rationale: Metformin (D) must be avoided in severe renal failure (GFR <10 mL/min), risking lactic acidosis due to reduced clearance. Prednisolone (A) and amoxicillin (B) are safe with adjustment. Bumetanide (C) is usable. Oxytetracycline (original E) needs caution but not avoidance. Metformin's renal excretion, critical in diabetes, demands strict contraindication, a key safety concern in renal impairment pharmacology.
Question 5 of 5
Which of the following is a True statement?
Correct Answer: B
Rationale: A is false:acetylation is phase II. B is true:theophylline follows zero-order kinetics at high doses with a narrow index. C is false:first-order eliminates a constant fraction, not amount. D is false:zero-order kinetics doesn't reach steady state predictably. B is correct, reflecting theophylline's clinical monitoring needs.