The Ames test is a method for detecting

Correct Answer: D

Rationale: The Ames test detects mutagenesis in bacteria (D), using Salmonella strains to identify reverse mutations from chemicals (e.g., aflatoxin), a rapid screen for potential carcinogens due to mutation-cancer correlation. Options A and B (carcinogenesis) require animal models, not bacteria. Option C (teratogenesis) involves developmental toxicity, not the Ames focus. Option E (original) is redundant with D. Developed by Bruce Ames, this assay's simplicity and sensitivity make it a cornerstone in genotoxicity screening, though positive results need animal confirmation for carcinogenicity, balancing cost and predictive power.

Correct Answer: D

Rationale: Aspirin (pKa 3.49) is most soluble at pH 4.0 (D). As a weak acid, its solubility increases when ionized (A⁻ form), per Henderson-Hasselbalch: pH = pKa + log([A⁻]/[HA]). At pH 4.0, pH > pKa, favoring ionization (log(0.51) ≈ 0.2, [A⁻] > [HA]), enhancing water solubility. At pH 1.0 (A), 2.0 (B), and 3.0 (C), pH < pKa, aspirin is mostly un-ionized (lipid-soluble), less soluble. pH 6.0 (original E) increases solubility further, but D is closest optimal. This pH-dependent solubility aids aspirin's absorption in the intestine (pH ~6), not stomach (pH ~2), guiding formulation strategies.

Correct Answer: B

Rationale: A very fine powder completely passes through a #120 sieve (B), with mesh size ~125 μm, per USP standards, ensuring small, uniform particles for rapid dissolution (e.g., in suspensions). Option A (#80, ~180 μm) is fine, not very fine. Option C (#20, ~850 μm) is coarse. Option D describes a fine powder range. Option E (original) is coarser still. This fineness enhances bioavailability and mixing, critical in formulations where particle size affects absorption rates, like oral powders or inhalants.

Correct Answer: A

Rationale: Divided powders are dispensed in individual-dose packets (A), pre-measured paper or foil packets (e.g., headache powders) ensuring accurate dosing and convenience. Bulk containers (B) suit undivided powders. Sifter-type containers (C) are for topical use, not oral doses. No option D or original E exists. This packaging protects hygroscopic or unstable drugs, enhancing patient compliance and stability, a traditional yet effective dispensing method in pharmacy practice.

Correct Answer: C

Rationale: Drugs are absorbed best from the duodenum (C) after oral administration, due to its large surface area (villi), neutral pH (~6-7), and long transit time, favoring ionization and dissolution (e.g., aspirin). Buccal (A) suits sublingual bypass. Stomach (B) has acidic pH, limiting weak acid absorption. Ileum (D) absorbs but less than duodenum. Rectum (original E) is for suppositories. This small intestinal dominance, post-gastric emptying, maximizes bioavailability, critical for oral drug design, though first-pass metabolism may reduce it.