Which of the following drugs is a nonselective alfa receptor antagonist?

Correct Answer: B

Rationale: The correct answer is B: Phentolamine. This drug is a nonselective alpha receptor antagonist, blocking both alpha-1 and alpha-2 receptors. It is used to treat hypertensive emergencies. Prazosin (A) is a selective alpha-1 receptor antagonist, used for hypertension and BPH. Metoprolol (C) is a beta blocker, mainly blocking beta-1 receptors for heart conditions. Reserpine (D) inhibits the uptake of norepinephrine into vesicles, reducing sympathetic activity.

Correct Answer: C

Rationale: The correct answer is C: Clonazepam. Clonazepam is a benzodiazepine commonly used for myoclonic seizures due to its ability to enhance the inhibitory neurotransmitter GABA in the brain, reducing seizure activity. Primidone (A), Carbamazepine (B), and Phenytoin (D) are more commonly used for other types of seizures like focal or generalized tonic-clonic seizures, not specifically for myoclonic seizures.

Correct Answer: A

Rationale: The correct answer is A because levodopa, as a precursor of dopamine, can cross the blood-brain barrier and be converted to dopamine in the brain, while dopamine itself cannot cross the blood-brain barrier when administered peripherally. Choice B is incorrect because dopamine-induced psychotic reactions are not the main reason for choosing levodopa. Choice C is also incorrect as levodopa is metabolized in the periphery before reaching the brain. Therefore, the correct choice is A as it addresses the main reason for using levodopa over dopamine.

Correct Answer: D

Rationale: The correct answer is D: Meperidine. Meperidine is the preferred opioid analgesic for relieving acute severe pain of renal colic due to its rapid onset of action and short duration of effect. It is particularly useful in this scenario as it provides quick pain relief without causing excessive sedation or respiratory depression. A: Morphine is a strong opioid analgesic but is not the preferred choice for renal colic due to its slower onset of action. B: Naloxone is an opioid antagonist and is used to reverse opioid overdose, not for pain relief. C: Methadone is a long-acting opioid analgesic and is not typically used for acute severe pain relief such as in renal colic.

Correct Answer: B

Rationale: Neuroleptics are primarily used to treat psychosis, which includes symptoms like hallucinations and delusions. These medications work by blocking dopamine receptors in the brain to reduce these symptoms. Neurosis (choice A) is a milder condition characterized by anxiety and distress, typically treated with psychotherapy. Narcolepsy (choice C) is a sleep disorder treated with stimulants. Parkinsonian disorders (choice D) are movement disorders and are treated with medications that increase dopamine levels. Therefore, the correct answer is B as neuroleptics are specifically designed to address symptoms associated with psychosis.