SBI-Letrozole

**SBI-Letrozole** is a proprietary formulation or investigational preparation of letrozole, a **third-generation non-steroidal aromatase inhibitor**. It competitively inhibits **CYP19A1 (aromatase)**, blocking the conversion of androgens to estrogens, thereby suppressing estrogen production primarily in postmenopausal women. This mechanism is leveraged for treating **hormone receptor-positive (HR+) breast cancer**, including early-stage, advanced, and metastatic disease, often in combination with CDK4/6 inhibitors like palbociclib or ribociclib. Letrozole has high oral bioavailability (99.9%), a half-life over 42 hours, and is administered as 2.5 mg tablets daily.[1][3]