**Question:** Drug of choice for ovulation induction -

A. Clomiphene Citrate
B. Human Menopausal Gonadotropin (hMG)
C. Human Chorionic Gonadotropin (hCG)
D. Leuprolide Acetate

**Core Concept:**

Ovulation induction refers to the process of stimulating the ovaries to produce more than one mature egg (ovum) for fertilization during in vitro fertilization (IVF) or other assisted reproductive techniques. This process is essential for successful pregnancy in cases of subfertility due to hormonal imbalances, polycystic ovary syndrome (PCOS), or other causes. The drugs used for this purpose work on different targets and mechanisms, which will be discussed in this explanation.

**Why the Correct Answer is Right:**

Clomiphene Citrate (CC) is a selective estrogen receptor modulator (SERM) that primarily works as an antiestrogen. It inhibits the negative feedback of estrogen on the hypothalamic-pituitary-ovarian axis, thereby stimulating the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) by the hypothalamus and pituitary gland, respectively. This results in the development of multiple follicles (ovulation) and a higher chance of ovulation and pregnancy.

**Why Each Wrong Option is Incorrect:**

B. Human Menopausal Gonadotropin (hMG) is a combination of both FSH and LH, which are essential for follicle development and ovulation. However, it is more expensive and requires injections, unlike CC, which is taken orally.

C. Human Chorionic Gonadotropin (hCG) is used to trigger ovulation but is not a primary ovulation-inducing drug. It is administered after a successful response to earlier treatment like hMG or CC.

D. Leuprolide Acetate (LA) is a gonadotropin-releasing hormone (GnRH) analogue, which suppresses the hypothalamic-pituitary-gonadal axis by blocking GnRH. This leads to a decrease in gonadotropins (FSH, LH) and subsequently results in a decrease in testosterone and estrogen levels. This is not the desired effect for ovulation induction, as suppressing hormone levels is counterproductive.

**Clinical Pearl:** Clomiphene Citrate's oral administration, affordability, and the fact that it primarily works via estrogen receptors make it the preferred choice for ovulation induction in many cases compared to hCG, hMG, and GnRH analogues like Leuprolide Acetate.