Which of the following statements is not correct?

Correct Answer: D

Rationale: The correct answer is D because the statement that the ALFA1a subtype mediates both vascular and prostate smooth muscle contraction is incorrect. The ALFA1a subtype primarily mediates prostate smooth muscle contraction, while the ALFA1b subtype is responsible for vascular smooth muscle contraction. This is a key distinction in understanding the roles of different subtypes of alfa1 receptors. Choices A, B, and C are all correct statements as there are indeed at least three subtypes of alfa1 receptors (alfa1a, alfa1b, and alfa1d), ALFA1a subtype does mediate prostate smooth muscle contraction, and ALFA1b subtype does mediate vascular smooth muscle contraction, respectively.

Correct Answer: A

Rationale: The correct answer is A: Gastrointestinal reactions, such as anorexia, pain, nausea, and vomiting. Ethosuximide is primarily used to treat absence seizures. Its common side effects include gastrointestinal reactions due to its irritant effect on the gastric mucosa. Anorexia, pain, nausea, and vomiting are commonly reported adverse effects. Exacerbated grand mal epilepsy (choice B) is not a known adverse effect of ethosuximide. Transient lethargy or fatigue (choice C) is a common side effect, but it is not dose-related. Therefore, the correct answer is A, as it accurately reflects the dose-related adverse effect of ethosuximide, while the other choices do not.

Correct Answer: D

Rationale: The correct answer is D: Trihexyphenidyl. Trihexyphenidyl is an anticholinergic drug that can worsen glaucoma by causing pupil dilation, leading to increased intraocular pressure. This can exacerbate the condition and potentially cause vision problems. Selegiline (A) is a monoamine oxidase inhibitor used in Parkinson's disease but does not affect glaucoma. Levodopa (B) is a gold standard treatment for Parkinson's and does not directly impact glaucoma. Bromocriptine (C) is a dopamine agonist used in Parkinson's but does not have a significant effect on glaucoma. Thus, the correct choice to avoid in patients with glaucoma is Trihexyphenidyl due to its potential to worsen the condition.

Correct Answer: D

Rationale: Alcohol causes an acute increase in the local concentrations of dopamine, opioid, and serotonin. Alcohol consumption leads to the release of dopamine, which is associated with pleasure and reward. It also activates the opioid system, contributing to its addictive properties. Additionally, alcohol affects the serotonin system, influencing mood regulation. Therefore, all of the above choices are correct because alcohol impacts the local concentrations of dopamine, opioid, and serotonin simultaneously.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Orthostatic hypotension can occur due to various mechanisms, such as central action of phenothiazines causing vasodilation, inhibition of norepinephrine uptake leading to decreased vasoconstriction, and alpha adrenoreceptor blockade reducing sympathetic response. Each of these factors can contribute to a drop in blood pressure upon standing. Choices A, B, and C all play a role in the development of orthostatic hypotension, making option D the correct comprehensive answer.