If the coma was caused by thio- pental, which of the following drug reactions was most likely involved?

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: 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: In this question, the correct answer is option A) Drugs P and Q. The rationale behind this is that drugs P and Q can fully activate the same receptors. This means that both drugs bind to the receptors and produce a maximal response. This is a key concept in pharmacology where drugs that fully activate the same receptors are considered to have similar pharmacological effects. Now, let's analyze why the other options are incorrect: - Option B) Drugs P and R: These drugs do not fully activate the same receptors, so they would not be the correct pair. - Option C) Drugs P and S: Similarly, these drugs do not fully activate the same receptors, making this option incorrect. - Option D) Drugs Q and T: These drugs also do not fully activate the same receptors, so they are not the correct pair. From an educational standpoint, understanding drug-receptor interactions is fundamental in pharmacology. Knowing which drugs can fully activate the same receptors is crucial in predicting their effects and potential interactions. This question tests students' knowledge of receptor activation and its implications in drug actions, highlighting the importance of specificity in pharmacological responses.

Correct Answer: B

Rationale: In this scenario, the correct answer is B) Partial agonist. A partial agonist is a drug that binds to a receptor and produces a response, but the response is less than that of a full agonist. In the context of the question, drug X is not a full agonist because it can be antagonized by drug Z, indicating that it does not fully activate the receptor. Competitive antagonist (option A) competes with the agonist for the same binding site on the receptor, but since drug Z antagonized drug X, it suggests that drug Z and X do not compete for the same binding site. Inverse agonist (option C) produces effects opposite to those of an agonist by reducing the basal activity of a receptor, which is not the case with drug X in this scenario. Irreversible antagonist (option D) permanently binds to the receptor, rendering it inactive, which is not the situation described in the question. Understanding the concept of partial agonists is crucial in pharmacology as it helps in comprehending how different drugs interact with receptors, leading to varied physiological responses. It also highlights the importance of drug-receptor interactions in pharmacotherapy and drug development.