Prevention of postmenopausal bone loss by pulsed estrogen therapy: comparison with transdermal route

OBJECTIVE: To compare the efficacy of pulsed estrogen therapy following intranasal 17beta-estradiol (E2) (S21400) with patch E2 in preventing postmenopausal bone loss and on bone turnover. METHODS: In this multinational open study, 361 postmenopausal women aged 51.5 (S.D. 4.6) years were treated with S21400 300 microg per day or patch E2 (delivering 50 microg per day), two patches per week, for 56 weeks. Bone mineral density (BMD) was assessed at the spine and hip using dual X-ray absorptiometry at baseline and week 56 (W56). Bone turnover markers (osteocalcin, bone alkaline phosphatase, urinary type I collagen C-telopeptides) were measured at baseline and weeks 12, 28 and 56. RESULTS: Spine and hip bone mineral density significantly increased in both groups (P < 0.001 versus baseline). Mean (S.D.) percent increases were 2.1 (3.0) at the spine (both groups), and 1.2 (2.4) and 1.1 (2.2) at the hip in the S21400 and patch E2 groups, respectively. Bone mineral density also significantly increased (P < 0.001 versus baseline) in osteopenic patients following S21400 and patch E2: 3.1 (3.5) and 2.4 (3.5) at the spine, and 2.0 (2.6) and 1.2 (2.7) at the hip, respectively. Bone metabolism was normalized at week 56 with a significant decrease (P < 0.001) from baseline in all markers: 56% and 53% for type I collagen C-telopeptides, and 24% and 25% for osteocalcin in the S21400 and patch E2 groups, respectively. CONCLUSION: Pulsed estrogen therapy was as effective in normalizing bone turnover and preventing postmenopausal bone loss as a reservoir patch.