PREVENTION OF POSTMENOPAUSAL BONE LOSS USING TIBOLONE OR CONVENTIONALPERORAL OR TRANSDERMAL HORMONE REPLACEMENT THERAPY WITH 17-BETA-ESTRADIOL AND DYDROGESTERONE

Postmenopausal bone loss can be prevented by continuous or intermitten t estradiol (E-2) administration. Concomitant progestogen therapy is m andatory in nonhysterectomized women to curtail the risk of endometria l hyperplasia or cancer. However, the recurrence of vaginal bleeding i nduced by sequential progestogen therapy in addition to continuous est rogen administration is one of the reasons for noncompliance to hormon e replacement therapy (HRT). Tibolone, a synthetic steroid with simult aneous weak estrogenic, androgenic, and progestational activity, which does not stimulate endometrial proliferation, has recently been propo sed for the treatment of climacteric symptoms. To compare the efficacy of conventional oral and transdermal HRT with that of tibolone in the prevention of postmenopausal bone loss, 140 postmenopausal women (age , 52 +/- 0.6 years; median duration of menopause, 3 years) were enroll ed in an open 2-year study. Volunteers had been offered a choice betwe en HRT and no therapy (control group, CO). Patients selecting HRT were randomly allocated to one of the following three treatment groups: TI B, tibolone, 2.5 mg/day continuously, orally; PO, peroral E-2, 2 mg/da y continuously, plus sequential oral dydrogesterone (DYD)), 10 mg/day, for 14 days of a 28-day cycle; TTS, transdermal E-2 by patch releasin g 50 mu g/day, plus DYD as above. Bone densitometry of the lumbar spin e, upper femur, and whole body was performed using dual-energy X-ray a bsorptiometry at baseline, and then 6, 12, 18, and 21 months after ini tiation of therapy. One hundred and fifteen women (82%) completed the 2 years of the study. The dropout rate was similar in each group. Over 2 years, bone preservation,vas observed in all three treatment groups as compared with controls, without significant differences among trea tment regimens. In conclusion, tibolone can be regarded as an alternat ive to conventional HRT to prevent postmenopausal bone loss.