antihormonal

Antihormonal refers to agents that oppose the actions of endogenous hormones by blocking receptor signaling, inhibiting hormone synthesis, or otherwise disrupting hormonal pathways. The term is used across pharmacology and medicine to describe drugs that reduce or counteract hormone activity.

Mechanisms include receptor antagonism (for example, tamoxifen blocks estrogen receptors in breast tissue), receptor downregulation or degradation (fulvestrant), enzyme inhibition that lowers hormone production (aromatase inhibitors such as letrozole and anastrozole reduce estrogen synthesis), and hypothalamic-pituitary suppression (GnRH agonists like leuprolide desensitize the axis, lowering gonadal hormone output). Some agents have tissue-selective actions (selective estrogen receptor modulators) and may act as antagonists in one tissue and agonists in another.

Major classes and examples include: Antiestrogens such as tamoxifen, raloxifene, and fulvestrant, used in hormone receptor–positive breast cancer and osteoporosis; Aromatase inhibitors such as anastrozole, letrozole, and exemestane, used in postmenopausal breast cancer; Antiandrogens such as flutamide, bicalutamide, enzalutamide, and apalutamide, used in prostate cancer; GnRH agonists such as goserelin and leuprolide to suppress gonadal hormones in various cancers; Antiprogestins such as mifepristone used for termination of pregnancy and certain gynecologic conditions.

Clinical considerations include effectiveness in hormone-dependent diseases and potential risks such as hot flashes, bone density loss, thromboembolism, liver toxicity, and metabolic effects. Treatment plans must balance benefits with adverse effects, and resistance can limit long-term efficacy. While the term antihormonal is broad, modern practice often uses specific descriptors like antiestrogen, antiandrogen, or hormone antagonist.