What factors regulate the relationship between the concentration of a drug and the association and dissociation of the drug-receptor complex?

Correct Answer: D

Rationale: The law of mass action governs the relationship between the concentration of a drug and the association and dissociation of the drug-receptor complex. According to this law, the rate of a chemical reaction is directly proportional to the product of the concentrations of the reacting substances. In the context of pharmacology, this means that the concentration of a drug influences its interaction with receptors, affecting the pharmacological response.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: B

Rationale: Lipid solubility of a drug is influenced by its pKa value. Since valproic acid has a pKa of 5, it would likely be lipid soluble at a pH of 7 in the duodenal lumen. The Henderson-Hasselbalch equation suggests that when the pH is higher than the pKa, the drug will predominantly be in its non-ionized, lipid-soluble form. In this case, the drug would be about 24% lipid soluble in the duodenal lumen, making choice B the correct answer.

Correct Answer: D

Rationale: The injected dose of cocaine can be calculated using the formula Dose = Cp * Vd, where Cp is the plasma concentration, and Vd is the volume of distribution. Given that the plasma level of cocaine was 0.75 mg/L, and the volume of distribution is about 130 L, the injected dose can be calculated as 0.75 * 130 = 97.5 mg, which is closest to option D.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.