L-thyroxin is useful in treatment of the following EXCEPT:

Correct Answer: C

Rationale: In the context of pharmacology of CNS drugs, understanding the role of L-thyroxine is crucial. L-thyroxine is a synthetic form of the thyroid hormone thyroxine, which is primarily involved in regulating metabolism. The correct answer, option C) Graves disease, is the exception because L-thyroxine is not used in the treatment of Graves disease. Graves disease is a condition characterized by overactivity of the thyroid gland, leading to hyperthyroidism. In Graves disease, treatment involves medications that block the production of thyroid hormones or procedures like radioactive iodine therapy or surgery to reduce thyroid activity. Options A) Myxedema and B) Cretinism are both conditions that result from hypothyroidism, which is a deficiency of thyroid hormone production. L-thyroxine is the primary treatment for hypothyroidism as it helps to supplement the deficient hormone levels in the body, thereby alleviating the symptoms associated with these conditions. In an educational context, this question highlights the importance of understanding the specific indications for medications in pharmacology. It underscores the need for students to differentiate between various thyroid disorders and their respective treatment approaches. By grasping these distinctions, students can develop a deeper comprehension of how pharmacological agents function in treating specific conditions, leading to more effective clinical decision-making in the future.

Correct Answer: B

Rationale: The correct answer is B) Acute adrenocortical insufficiency. Explanation: When glucocorticoids are withdrawn suddenly after prolonged therapy, the body's natural production of cortisol may be suppressed. This can lead to acute adrenocortical insufficiency because the adrenal glands have become dependent on exogenous glucocorticoids. As a result, the body is unable to produce enough cortisol to meet its needs, leading to symptoms of adrenal insufficiency such as weakness, fatigue, hypotension, and in severe cases, adrenal crisis. Why others are wrong: A) Hypertensive crisis: Sudden withdrawal of glucocorticoids is more likely to cause hypotension rather than hypertension due to the lack of cortisol to maintain blood pressure. C) Cardiac arrhythmias: While prolonged corticosteroid use can have cardiac effects, sudden withdrawal is more likely to cause systemic effects related to cortisol deficiency rather than isolated cardiac arrhythmias. D) Angina pectoris: Glucocorticoid withdrawal is not typically associated with the development of angina pectoris. Educational context: Understanding the effects of prolonged glucocorticoid therapy and the consequences of sudden withdrawal is essential in pharmacology education. It highlights the importance of tapering off glucocorticoid therapy gradually to allow the body's natural cortisol production to resume. This knowledge is crucial in clinical practice to prevent adverse effects and manage patients on corticosteroid therapy effectively.

Correct Answer: D

Rationale: Octreotide (choice D), a somatostatin analog, treats acromegaly by inhibiting growth hormone from pituitary tumors, reducing symptoms. Cosyntropin (choice A) tests adrenal function, Desmopressin (choice B) manages diabetes insipidus, Leuprolide (choice C) targets sex hormones. Octreotide is specific.

Correct Answer: C

Rationale: In the scenario presented, the correct answer is C) Insulin plus fluid therapy plus potassium. Explanation of why C is correct: 1. **Insulin**: Essential for correcting hyperglycemia by promoting glucose uptake. 2. **Fluid therapy**: Helps correct dehydration and electrolyte imbalances secondary to ketoacidosis. 3. **Potassium**: Replacement is crucial as insulin administration can lead to intracellular shift of potassium, potentially causing hypokalemia. Explanation of why others are wrong: 1. **A) Insulin alone**: While insulin is necessary, it alone does not address the electrolyte imbalances seen in diabetic ketoacidosis. 2. **B) Insulin plus fluid therapy**: Fluid therapy is crucial, but without potassium replacement, there is a risk of hypokalemia. 3. **D) Insulin plus fluid therapy plus sodium bicarbonate**: Sodium bicarbonate is no longer routinely recommended in the treatment of diabetic ketoacidosis as it may lead to paradoxical cerebrospinal acidosis. Educational context: Understanding the comprehensive approach to managing diabetic ketoacidosis in pediatric patients is vital for healthcare providers. This case emphasizes the importance of addressing not only hyperglycemia with insulin but also correcting dehydration and electrolyte imbalances to ensure a successful outcome for the patient.

Correct Answer: A

Rationale: The correct answer is A) Glucocorticoids inhibit both prostaglandin production and inflammatory cells. Glucocorticoids, like dexamethasone, exert their anti-inflammatory effects through multiple mechanisms. They inhibit the production of inflammatory mediators such as prostaglandins by suppressing the expression of cyclooxygenase-2 (COX-2) enzyme and thereby reducing the synthesis of prostaglandins involved in the inflammatory response. In contrast, option B) stating that glucocorticoids are more potent inhibitors of cyclooxygenase than naproxen is incorrect because glucocorticoids do not directly inhibit the enzyme cyclooxygenase like NSAIDs such as naproxen do. Option C) is incorrect because glucocorticoids do not directly inhibit COX-1 and COX-2 biosynthesis. Option D) is also incorrect as glucocorticoids primarily act as anti-inflammatory agents rather than analgesics. Educationally, understanding the mechanisms of action of different classes of drugs is crucial in pharmacology. In this case, knowing how glucocorticoids exert their anti-inflammatory effects can help healthcare providers make informed decisions when selecting appropriate treatment options for patients with inflammation that is unresponsive to initial therapy.