ATI RN
Chapter 26 principles of pharmacology Questions
Question 1 of 5
With regard to clinical trials of new drugs, which of the following is most correct?
Correct Answer: A
Rationale: Phase I involves the study of a small number of normal volunteers by highly trained clinical pharmacologists (A), assessing safety, pharmacokinetics, and tolerability (e.g., 20-100 subjects) in controlled settings. Phase II (B) tests efficacy in patients (100-300), not thousands. Phase III (C) compares efficacy and safety in larger populations (300-3000), not inducing toxicity for therapeutic index. Option D is irrelevant. Phase II with controls (original E) is true but less defining than A. Phase I's focus on healthy subjects establishes safe dosing, critical for advancing drug development, balancing risk and scientific rigor.
Question 2 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 3 of 5
Vanishing cream is an ointment that may be classified as
Correct Answer: D
Rationale: Vanishing cream is an emulsion base (D), typically oil-in-water (o/w), disappearing on skin application as water evaporates, leaving a non-greasy film (e.g., cosmetic creams). Water-soluble bases (A) dissolve in water (e.g., PEG ointments), oleaginous bases (B) are greasy (e.g., petrolatum), and absorption bases (C) absorb water (e.g., lanolin). Option E (original) is invalid. This o/w emulsion enhances drug delivery (e.g., hydrocortisone) and patient compliance due to its aesthetic appeal, contrasting with greasy bases in topical formulations.
Question 4 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 5 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.