Sublingual absorption of micronized 17beta-estradiol.

The sublingual absorption rates, the sustained effects, te biologic activity, and the metabolism of micronized 17beta-estradiol (E2) were measured in 10 postmenopausal women. E2 (0.5 mg) was administered in a single sublingual dose to five of the patients. An alternate-day schedule with the same dosage was used for the other five patients. In the single-dose study, a twenty-six fold increase in serum E2 and a ninefold increase in serum estrone (E1) concentrations were observed 1 hour after the sublingual deposition of E2 (0.5 mg). Serum concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were significantly decreased within 6 hours. The rise in E2 was early and peaked in the first 2 hours. The rise in E1 was slower and progressive, reaching its maximum thirteenfold increase at 4 hours, and remained two and one half times the baseline of 29 pg/ml at 24 hours, whereas E2 returned to the baseline level of 24 pg/ml. When micronized E2 was given in a dosage of 0.5 mg sublingually every other night, increased circulating levels of estrogens continued to be elevated at a minimum two and one-half fold baseline level for the week of study.