Which of the following terms best defines the tested drug?

Correct Answer: A

Rationale: The tested drug is best defined as a noncompetitive antagonist, which binds irreversibly to the receptor site and prevents the activation of the receptor by the endogenous ligand. This property distinguishes noncompetitive antagonists from other types of drugs and is important in understanding their mechanism of action and therapeutic effects.

Correct Answer: D

Rationale: The coma caused by thio- pental is most likely due to a pseudoallergic reaction, as this type of reaction can lead to severe symptoms such as seizures and coma. Pseudoallergic reactions are non-immunologic reactions that can occur in individuals even without prior exposure to the drug, making them unpredictable and potentially life-threatening. In this case, the patient's history of acute intermittent porphyria may have contributed to the pseudoallergic reaction to thio- pental.

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.