A 78-year-old male with Parkinson’s disease experiences worsening of his symptoms. He is already taking levodopa. Since the disease is characterized by degeneration of dopaminergic neurons, leading to the lack of inhibition of cholinergic neurons, the addition of which medication is likely to help alleviate the patient’s symptoms?

Correct Answer: A

Rationale: The correct answer is A: Benztropine. Benztropine is an anticholinergic medication that helps alleviate Parkinson's disease symptoms by blocking the excess activity of acetylcholine, which is increased due to the lack of dopaminergic inhibition. This leads to a rebalancing of neurotransmitters in the brain, improving motor symptoms. Choice B: Reserpine depletes neurotransmitters including dopamine, worsening Parkinson's symptoms. Choice C: Doxazosin is an alpha-blocker used for hypertension, not Parkinson's disease. Choice D: Timolol is a beta-blocker used for glaucoma, not Parkinson's disease.

Correct Answer: C

Rationale: The correct answer is C: To treat hypertension. Adrenaline, also known as epinephrine, is not typically used to treat hypertension because it can worsen high blood pressure due to its vasoconstrictive effects. Adrenaline is used to prolong the action of local anesthetics (A), stop epistaxis (B), and treat anaphylaxis (D) due to its ability to constrict blood vessels and increase heart rate in emergency situations.

Correct Answer: B

Rationale: The correct answer is B. Nicotinic receptors are not associated with decreased gastric acid secretion, but rather with muscle contraction at neuromuscular junctions. A: Muscarinic receptors stimulation leads to decreased heart rate via parasympathetic activation. C: Activation of alpha adrenergic receptors causes vasoconstriction and increased blood pressure. D: Stimulation of beta adrenergic receptors results in bronchodilation and increased heart rate. Therefore, choice B is the exception as it does not match the typical response of nicotinic receptors.

Correct Answer: D

Rationale: Step 1: Alpha methyl dopa is a centrally acting antihypertensive medication. Step 2: It is a prodrug that is converted to alpha-methyl norepinephrine in the brain. Step 3: This metabolite stimulates alpha2 receptors in the brain, leading to decreased sympathetic outflow. Step 4: Decreased sympathetic outflow results in decreased peripheral vascular resistance and ultimately decreases blood pressure. Summary: Option D is correct because alpha methyl dopa decreases blood pressure by acting centrally on alpha2 receptors. Options A, B, and C are incorrect as alpha methyl dopa does not inhibit decarboxylase enzyme, increase renin, or stimulate alpha2 receptors centrally.

Correct Answer: D

Rationale: The correct answer is D: Stimulate uterine contraction. Selective β2 agonists primarily target β2 receptors in the lungs, leading to bronchodilation. They have minimal effect on β1 receptors, thus do not significantly impact heart rate or blood pressure. However, β2 receptors in the uterus can cause uterine relaxation, not contraction. Therefore, selective β2 agonists do not stimulate uterine contractions. Choices A, B, and C are incorrect as they align with the typical effects of selective β2 agonists.