The drug of choice for status epilepticus is

Correct Answer: A

Rationale: The correct answer is A: Diazepam. This is because Diazepam is a fast-acting benzodiazepine that helps terminate seizures quickly, making it the drug of choice for status epilepticus. It works by enhancing the effects of the inhibitory neurotransmitter GABA, which helps to calm excessive electrical activity in the brain during a seizure. Phenobarbital (B) and Phenytoin (C) are not recommended as first-line treatments for status epilepticus due to slower onset of action. Valproic Acid (D) is also not the drug of choice for status epilepticus as it is typically used for long-term seizure management rather than acute seizure control.

Correct Answer: A

Rationale: The correct answer is A: Sedative-hypnotic. Zolpidem is used to treat insomnia by promoting sleep onset and improving sleep maintenance. It acts on the central nervous system to enhance the inhibitory neurotransmitter GABA. This classification is based on its pharmacological effects and mechanism of action. B: Anti-anxiety drug - Zolpidem is not primarily indicated for anxiety disorders but for insomnia. C: Anti-convulsant - Zolpidem is not used to prevent or control seizures, so it is not classified as an anti-convulsant. D: Muscle relaxant - Zolpidem does not have a direct effect on muscle relaxation, so it is not classified as a muscle relaxant.

Correct Answer: B

Rationale: The correct answer is B: Fraction of an unchanged drug reaching the systemic circulation following any route of administration. Bioavailability refers to the proportion of an administered dose of unchanged drug that reaches the systemic circulation. This is crucial in determining the effectiveness of a drug. Option A is incorrect because bioavailability is not specifically related to the amount excreted in urine. Option C is incorrect as it refers to permeability through the blood-brain barrier, which is a different concept. Option D is incorrect as it pertains to plasma protein binding, which is not the same as bioavailability. In summary, bioavailability is about the amount of a drug that reaches systemic circulation intact, making option B the correct choice.

Correct Answer: A

Rationale: The correct answer is A because half-life is the time taken for the concentration of a drug in the plasma to decrease by 50%. This is a measure of the rate of elimination of a drug from the body. Choice B is incorrect because half-life does not specifically refer to metabolism. Choice C is incorrect because absorption is not related to half-life. Choice D is incorrect because half-life is not about binding to plasma proteins but about elimination from the body.

Correct Answer: D

Rationale: The correct answer is D because bound drug is not the pharmacologically active part of the drug. The active form of a drug is the unbound fraction that can exert its pharmacological effects. When a drug is bound to plasma proteins, it is unable to exert its pharmacological action until it becomes unbound. Choice A is true because bound drug cannot diffuse into tissues. Choice B is correct because binding to plasma proteins decreases the apparent volume of distribution. Choice C is also true as displacement of bound drug can lead to increased effects of the drug due to increased free drug concentration.