This is an estrogen antagonist.

Indications: to reduce the incidence of breast cancer in women at high risk for developing breast cancer disease; metastatic breast cancer; infertility in women with anovulatory disorders.

Cautions: pregnancy and breast-feeding; occasional cystic ovarian swellings in premenopausal women, occasional hypercalcaemia if bony metastases; increased risk of thromboembolic events when used with cytotoxics; porphyria.

Contra-indications: pregnancy.

Side Effects: amenorrhoea in premenopausal women; hot flushes; vaginal bleeding, gastro-intestinal disturbances, endometrial cancer, increase triglyceride, thromboembolism, visual disorders.

Dose: breast cancer, initially 20 mg daily. Anovulatory infertility, 20 mg daily on second, third, fourth and fifth days of cycle.

Doses may be increased to 40 mg then 80 mg for subsequent courses.

If cycles irregular, start initial course on any day, with subsequent courses starting 45 days later or on second day of cycle if menstruation occurs.