letrozole + estradiol valerate

This combination therapy consists of letrozole, a non-steroidal aromatase inhibitor, and estradiol valerate, a synthetic ester of the natural estrogen 17β-estradiol. It is primarily investigated for the management of Polycystic Ovary Syndrome (PCOS), specifically to improve ovulation induction outcomes. Letrozole induces ovulation by inhibiting the enzyme aromatase, which prevents the conversion of androgens to estrogens; this reduction in systemic estrogen levels removes negative feedback on the pituitary gland, leading to increased secretion of follicle-stimulating hormone (FSH). Estradiol valerate is co-administered to counteract the thin endometrial lining that can sometimes result from letrozole's hypoestrogenic effect, thereby enhancing endometrial thickness and receptivity to improve pregnancy rates.

Other names

letrozole and estradiol valerate combination