Levonorgestrel and 17β-estradiol given transdermally for the prevention of postmenopausal osteoporosis

Aim: To evaluate the efficacy and safety of a new transdermal continuous combined hormone replacement therapy (HRT) for the prevention of postmenopausal osteoporosis. Methods: 212 osteopenic (lumbar spine and/or hip (femoral neck) bone mineral density (BMD) between −1.0 and −2.5 S.D. of the premenopausal mean value) postmenopausal women aged 45-65 years participated in a 2-year prospective study. Treatments were 45 μg 17β-estradiol combined with 30 (n = 69) or 40 μg (n = 72) levonorgestrel daily or placebo (n = 71) given as a 7-day patch. All received a daily supplement of 500 mg calcium. BMD at lumbar spine (L2-L4), hip and total body, as well as blood and urinary biochemical markers of bone turnover (serum osteocalcin (sOC), serum bone-specific alkaline phosphatase (sBSAP), urinary calcium (uCa) and urinary CrossLaps (uCTX)) were measured regularly. Results: BMD at the lumbar spine, hip and total body increased by 8, 6 and 3% (P < 0.001), respectively, in the hormone groups versus placebo. The bone markers all decreased accordingly (sOC: 37%, sBSAP: 34% and uCTX: 65% from baseline (all P < 0.001)), except for uCa that did not change significantly. No significant dose-related effect of levonorgestrel was found. Vaginal bleeding/spotting decreased from 48 to 25% of the HRT-treated women during the study period. Skin tolerance was good in 84% of the women with no difference between the study groups. No incidences of endometrial hyperplasia, uterine or mammary cancer occurred. Conclusion: The transdermal combination of 17β-estradiol and levonorgestrel has a positive effect on BMD in an osteopenic postmenopausal population. Furthermore, a high safety profile was observed.