Skin patch for use in Hormone Replacement Therapy (HRT). A single transdermal skin patch, brand name Estraderm TTS 50, manufactured by Ciba-Geigy. This self-adhesive skin patch is impregnated with 4 milligrams of the female hormone oestradiol (a type of oestrogen) and releases some 50 micrograms of the hormone in 24 hours when in contact with the skin. Hormone Replacement Therapy is a method of treating a hormone deficiency. Oestrogen replacement therapy is typically given to relieve menopausal symptoms in women. These symptoms can include hot flushes, sweating at night, & atrophic vaginitis. HRT also helps prevent atherosclerosis and osteoporosis (reduction in bone density).