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Problems with compliance caused by breakthrough bleeding with hormone replacement therapy (HRT) may not be an issue in another year if Parke-Davis Pharmaceutical Research in Ann Arbor, MI, has its way. The company is seeking U.S. Food and Drug Administration approval for an HRT dosing regimen determined by the recent CHART study.1 The new formulation is the brainchild of Leon Speroff, MD, professor of OB/GYN at Oregon Health Sciences University in Portland.
Rather than being based on conjugated equine estrogen (CEE) alone or in combination with a progestin like medroxyprogesterone acetate (MPA), as all other HRT formulations are, Speroff’s idea was to combine ethinyl estradiol (EE2) and norethindrone acetate (NA), just like combined oral contraceptives only at a lower dose. His CHART study examined 695 post-menopausal women at 65 sites at the end of a two-year period, each of whom was randomized to placebo or to one of eight treatment groups. The treatments were either various combinations of EE2 and NA, or EE2 alone.
By balancing the outcomes of BMD, endometrial effects, lipids, and bleeding, Speroff’s team was able to determine for Parke-Davis that the formulations most worthwhile were 0.5 mg NA plus 2.5 mg EE2 and 1 mg NA plus 5 mg EE2.