Which of the following cell elements represent the main site of therapeutic action of levothyroxine?

Correct Answer: D

Rationale: The correct answer is D: Cell nucleus. Levothyroxine acts by binding to thyroid hormone receptors in the cell nucleus, where it regulates gene expression. This is essential for controlling metabolism and energy production. Choices A, B, and C are incorrect because levothyroxine's mechanism of action does not involve the cell membrane, mitochondria, or smooth endoplasmic reticulum. The nucleus is where genetic material is stored and gene expression is controlled, making it the main site of action for levothyroxine.

Correct Answer: A

Rationale: The correct answer is A: Fludrocortisone. Fludrocortisone is a synthetic mineralocorticoid used to treat adrenal insufficiency by replacing aldosterone. It helps regulate electrolyte balance and blood pressure. Edrophonium, Azathioprine, and Neostigmine are not mineralocorticoids and are used for different conditions like myasthenia gravis and autoimmune diseases.

Correct Answer: C

Rationale: The correct answer is C: To avoid opportunistic infections after surgery. Prednisone is a corticosteroid that suppresses the immune system, which can increase the risk of infections. Restarting prednisone post-surgery may be necessary to prevent opportunistic infections due to the patient's suppressed immune response. Choices A, B, and D are incorrect because adrenal insufficiency, wound healing, and gallbladder relaxation are not typically primary goals for restarting prednisone treatment in this context.

Correct Answer: D

Rationale: The correct answer is D: Dexamethasone. 1. Acute iridocyclitis is an inflammation of the iris and ciliary body, requiring a potent anti-inflammatory drug like a corticosteroid. 2. Dexamethasone is a potent corticosteroid that helps reduce inflammation in the eye, making it suitable for treating acute iridocyclitis. 3. Indomethacin (A) is a nonsteroidal anti-inflammatory drug (NSAID) which may not be as effective in controlling the inflammation in the eye. 4. Apraclonidine (B) and Timolol (C) are both used to lower intraocular pressure in conditions like glaucoma, not for treating inflammation like in acute iridocyclitis. In summary, Dexamethasone is the appropriate choice for treating acute iridocyclitis due to its potent anti-inflammatory properties, while the other options are not as effective for this specific condition

Correct Answer: C

Rationale: The correct answer is C: Levonorgestrel. Levonorgestrel is a progestin commonly used for emergency contraception due to its effectiveness in preventing pregnancy when taken shortly after unprotected intercourse. It works by inhibiting ovulation and fertilization. Clomiphene (A) is used to induce ovulation, not for emergency contraception. Leuprolide (B) is a gonadotropin-releasing hormone agonist used for conditions like endometriosis or prostate cancer, not for emergency contraception. Fulvestrant (D) is a selective estrogen receptor degrader used in breast cancer treatment, not for emergency contraception.