ATI RN
Chapter 26 principles of pharmacology Questions
Question 1 of 5
The pH of a buffer system can be calculated with the
Correct Answer: B
Rationale: The Henderson-Hasselbalch equation (B) calculates the pH of a buffer system, pH = pKa + log([Aâ»]/[HA]), balancing weak acid/base and conjugate forms (e.g., acetate buffer). Noyes-Whitney (A) governs dissolution rates. Michaelis-Menten (C) describes enzyme kinetics. Yong (D) and Stokes (original E) are unrelated to buffers. This equation predicts ionization (e.g., aspirin at pH 7.4), crucial for drug absorption and formulation stability, maintaining pH despite acid/base challenges, a key principle in pharmaceutical buffering.
Question 2 of 5
The shells of soft gelatin capsules may be made elastic or plastic-like by the addition of
Correct Answer: A
Rationale: Sorbitol (A) makes soft gelatin capsule shells elastic or plastic-like, a polyol plasticizer softening the gelatin matrix, enhancing flexibility (e.g., vitamin D capsules). Povidone (B) is a binder, not a plasticizer here. Polyethylene glycol (C) can plasticize but is less common. Lactose (D) is a filler, not elasticizing. pKa (original E) is irrelevant. Sorbitol's hygroscopicity maintains shell integrity, improving handling and patient acceptability in liquid-filled capsules, a key formulation advantage.
Question 3 of 5
Match the drug product below with the type of controlled-release dosage form that it represents
Correct Answer: A
Rationale: A matrix device (A) matches Biphenamine Capsules (1), where drug release occurs via diffusion through an inert matrix (e.g., wax). Ion-exchange (B) fits Thorazine Spansule (2), releasing via resin binding. Hydrocolloid (C) suits Valrelease (3), swelling to control release. Osmotic system (D) matches Slow-K (4), using osmotic pressure. Coated granules (original E) are distinct. Matrix systems provide sustained release, balancing simplicity and efficacy, widely used for chronic conditions, minimizing peak-trough fluctuations.
Question 4 of 5
The rate of drug bioavailability is most rapid when the drug is formulated as a
Correct Answer: D
Rationale: A solution (D) offers the most rapid bioavailability rate, as the drug is pre-dissolved, bypassing disintegration and dissolution (e.g., oral syrups absorbed in minutes). Controlled-release (A) delays release. Hard gelatin capsules (B) and tablets (C) require disintegration. Suspension (original E) is fast but slower than solutions. This immediacy maximizes absorption speed, ideal for acute conditions, though solutions may face stability or palatability challenges in formulation.
Question 5 of 5
All of the following statements about plasma protein binding of a drug are true except
Correct Answer: D
Rationale: Option D is false; drugs highly bound to plasma proteins (e.g., warfarin) have a smaller V_D, as they stay in plasma, unlike tissue-bound drugs (e.g., digoxin, large V_D). Displacement increases V_D transiently (A), boosts free drug for filtration (B), and risks toxicity in highly bound drugs (C), all true. Option E (original) is replaced. Protein binding restricts distribution, reducing V_D, a key pharmacokinetic factor affecting free drug levels and potential interactions, critical in polypharmacy.