Which of the following barbiturates is an ultra-short-acting drug?

Correct Answer: C

Rationale: Thiopental is the correct answer because it is an ultra-short-acting barbiturate with a rapid onset and short duration of action. It is commonly used for induction of anesthesia due to its fast-acting properties. Secobarbital and Amobarbital are short to intermediate-acting barbiturates, while Phenobarbital is a long-acting barbiturate used for seizure control. In summary, Thiopental stands out as the ultra-short-acting option compared to the other choices due to its specific pharmacokinetic profile.

Correct Answer: B

Rationale: The correct answer is B: Sinemet. Sinemet combines carbidopa and levodopa in a fixed proportion. Carbidopa helps prevent the breakdown of levodopa before it reaches the brain, increasing levodopa's effectiveness. Selegiline (A) is a monoamine oxidase inhibitor, not a combination with carbidopa/levodopa. Tolcapone (C) is a COMT inhibitor, not a combination product. Biperiden (D) is an anticholinergic medication used for Parkinson's disease symptoms but does not contain carbidopa/levodopa.

Correct Answer: C

Rationale: The correct answer is C: Naloxone. Naloxone is a pure opioid antagonist that quickly reverses the effects of opioid overdose by competing for opioid receptor sites. It is used in the treatment of acute opioid overdose to rapidly restore normal respiration and consciousness. Choice A: Pentazocine is a mixed opioid agonist-antagonist and is not used to treat opioid overdose. Choice B: Methadone is a long-acting opioid agonist primarily used for opioid maintenance therapy, not for acute overdose reversal. Choice D: Remifentanil is a short-acting opioid analgesic used during surgery and is not indicated for opioid overdose treatment.

Correct Answer: B

Rationale: The correct answer is B: Benztropine mesylate. Benztropine is an anticholinergic medication that helps alleviate extrapyramidal reactions by blocking excess acetylcholine activity in the brain. Levodopa (A) is used to treat Parkinson's disease but can worsen extrapyramidal reactions. Bromocriptine (C) is a dopamine agonist used in Parkinson's disease, not for treating extrapyramidal reactions directly. Dopamine (D) itself is not used to treat extrapyramidal reactions as it does not directly address the underlying mechanism of the condition.

Correct Answer: A

Rationale: The correct answer is A: Tranylcypromine. Tranylcypromine is a monoamine oxidase inhibitor (MAOI) that can rapidly increase synaptic concentrations of neurotransmitters. Due to this mechanism of action, it can have a short latency period of as little as 48 hours. Incorrect answers: B: Imipramine is a tricyclic antidepressant that typically takes 2-4 weeks to show therapeutic effects. C: Fluoxetine is an SSRI that usually takes 2-6 weeks for full efficacy. D: Amitriptyline is a tricyclic antidepressant with a similar latency period to imipramine, typically 2-4 weeks.