Which of the following drugs is useful in the treatment of Parkinson′s disease?

Correct Answer: A

Rationale: The correct answer is A: Benztropine. Benztropine is an anticholinergic drug that helps improve symptoms of Parkinson's disease by blocking excess acetylcholine in the brain, thus restoring a balance between dopamine and acetylcholine. This helps alleviate tremors, muscle stiffness, and other motor symptoms associated with Parkinson's. Summary of other choices: B: Edrophonium is a reversible acetylcholinesterase inhibitor used for diagnosing myasthenia gravis. C: Succinylcholine is a depolarizing neuromuscular blocker used for muscle relaxation during surgeries. D: Hexamethonium is a ganglionic blocker used to lower blood pressure.

Correct Answer: B

Rationale: The correct answer is B: Metoprolol. Metoprolol is a beta1-selective antagonist, meaning it selectively blocks beta1-adrenergic receptors. This specificity results in decreased heart rate and contractility without affecting beta2 receptors, which are primarily found in the lungs. Choice A, Propranolol, is a non-selective beta blocker that blocks both beta1 and beta2 receptors. Choice C, Carvedilol, is a non-selective beta blocker with additional alpha-blocking activity. Choice D, Sotalol, is a non-selective beta blocker with Class III antiarrhythmic properties. Therefore, the correct answer is B as it is the only beta1-selective antagonist among the options provided.

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: D

Rationale: Step 1: Identify the adverse effects mentioned in the question: Granulocytopenia, gastrointestinal irritation, gingival hyperplasia, and facial hirsutism. Step 2: Recognize the common side effects associated with each drug. Step 3: Phenytoin is known to cause granulocytopenia, gingival hyperplasia, and facial hirsutism. It can also cause gastrointestinal irritation. Step 4: Eliminate other choices: Phenobarbital is not known to cause these side effects. Carbamazepine does not commonly lead to gingival hyperplasia or facial hirsutism. Valproate does not typically cause these specific adverse effects. Step 5: Therefore, the correct answer is D (Phenytoin) as it matches all the mentioned adverse effects.

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.