Finasteride acts by:

Correct Answer: D

Rationale: The correct answer is D because finasteride inhibits the enzyme 5-alpha reductase, which is responsible for converting testosterone to dihydrotestosterone (DHT). By lowering circulating as well as prostatic DHT concentration, finasteride effectively reduces the androgenic effect on the prostate, leading to shrinkage of the prostate gland and improvement in symptoms of benign prostatic hyperplasia. A: Blocking testosterone receptors in the prostate gland is incorrect because finasteride does not directly block testosterone receptors. B: Reducing testosterone secretion from testes is incorrect because finasteride does not affect testosterone secretion. C: Reducing LH secretion from pituitary is incorrect because finasteride does not directly influence LH secretion.

Correct Answer: D

Rationale: The correct answer is D: Conjugated estrogens. Conjugated estrogens are derived from the urine of pregnant mares and contain a mixture of estrogens like estrone and equilin. They are commonly used for hormone replacement therapy in menopausal women due to their effectiveness in relieving menopausal symptoms. A: Ethinylestradiol is a synthetic estrogen commonly used in birth control pills, not as hormone replacement therapy in menopausal women. B: Estradiol benzoate is a form of estradiol used in veterinary medicine, not typically used in hormone replacement therapy for menopausal women. C: Diethylstilbestrol is a synthetic nonsteroidal estrogen that has been largely discontinued due to its association with serious health risks, not commonly used for hormone replacement therapy in menopausal women.

Correct Answer: D

Rationale: The correct answer is D because both Raloxifene (a selective estrogen receptor modulator) and Alendronate (a bisphosphonate) are commonly used to treat osteoporosis. Raloxifene helps prevent bone loss and reduces fracture risk, while Alendronate slows down bone breakdown. Pamidronate (choice C) is not typically used for osteoporosis treatment. Therefore, choices A, B, and C are incorrect.

Correct Answer: D

Rationale: The correct answer is D: Calcitriol. Calcitriol is the active form of vitamin D and is the most suitable preparation for vitamin D dependent rickets as it directly increases calcium absorption in the intestines and promotes bone mineralization. Calcitriol is essential for regulating calcium and phosphorus levels in the body. Choice A, Calciferol, is a general term for vitamin D compounds and is not specific enough for rickets treatment. Choice B, Cholecalciferol, is the precursor form of vitamin D and needs to be converted to calcitriol in the body. Choice C, Calcifediol, is an intermediate form that also requires conversion to calcitriol for biological activity. Therefore, calcitriol is the most appropriate choice for treating vitamin D dependent rickets due to its direct action on calcium metabolism and bone health.

Correct Answer: B

Rationale: The correct answer is B: Parathormone. Parathormone stimulates osteoclast activity, which leads to increased bone resorption. Estrogens (choice A) actually inhibit bone resorption. Bisphosphonates (choice C) are used to decrease bone resorption. Calcitonin (choice D) also inhibits bone resorption by blocking osteoclast activity. Therefore, the correct choice is parathormone as it directly accelerates bone resorption by stimulating osteoclasts.