Which of the following drugs is useful in the treatment of pheochromocytoma?

Correct Answer: C

Rationale: The correct answer is C: Phentolamine. Phentolamine is an alpha-adrenergic antagonist that helps block the effects of excess catecholamines released by pheochromocytoma. It helps to control hypertension and other symptoms associated with pheochromocytoma. A: Phenylephrine is an alpha-1 adrenergic agonist, which would worsen hypertension in pheochromocytoma. B: Propranolol is a beta-blocker, which can lead to unopposed alpha-adrenergic effects and exacerbate hypertension in pheochromocytoma. D: Epinephrine is a catecholamine that would exacerbate symptoms in pheochromocytoma due to its stimulatory effects on alpha and beta adrenergic receptors.

Correct Answer: D

Rationale: Lamotrigine is an antiepileptic drug that is effective in treating partial seizures, absence seizures, and myoclonic seizures. Therefore, the correct answer is D, "All of the above." It works by stabilizing neural membranes and inhibiting glutamate release. It is commonly used as a first-line treatment for various types of seizures. Choices A, B, and C are incorrect because lamotrigine can indeed be used to treat all these seizure types based on its mechanism of action and clinical effectiveness.

Correct Answer: B

Rationale: The correct answer is B: Hypertensive emergency. When levodopa is combined with an inhibitor of both forms of monoamine oxidase, it can lead to an excessive buildup of catecholamines, causing a hypertensive crisis due to the potentiation of sympathetic effects. This can result in severe hypertension, which can lead to a hypertensive emergency characterized by organ damage and potentially life-threatening complications. Respiratory depression (choice A), acute psychotic reactions (choice C), and cardiovascular collapse and CNS depression (choice D) are not the main risks associated with the combined administration of levodopa and MAO inhibitors.

Correct Answer: C

Rationale: The correct answer is C: Severe loss of potassium and magnesium. Chronic alcohol abuse can lead to gastrointestinal issues, causing malabsorption of essential nutrients like potassium and magnesium. This can result in electrolyte imbalances, leading to severe loss of these minerals. Hyperglycemia (A) is not typically associated with chronic alcohol abuse. Increased serum phosphate (B) levels are not commonly seen with alcohol abuse. Decreased serum sodium (D) is not a typical metabolic alteration associated with chronic alcohol abuse.

Correct Answer: A

Rationale: Phenothiazine derivatives are known to block dopamine receptors in the hypothalamus, leading to a decrease in body temperature, causing hypothermia (Choice A). Choices B, C, and D are incorrect because phenothiazines do not directly affect prolactin levels, corticotrophin release, pituitary growth hormone secretion, appetite, or weight. The mechanism of action of phenothiazines specifically targets the dopamine receptors to produce hypothermia.