Effects on serum lipid profiles of continuous 17beta-estradiol, intermittent norgestimate regimens versus continuous combined 17beta-estradiol/norethisterone acetate hormone replacement therapy.

OBJECTIVE

To compare the effects of a daily oral 1-mg dose of continuous 17beta-estradiol (E2) plus intermittent (3 days off, 3 days on) norgestimate (NGM) 90 microg (n = 221), an oral 2-mg dose of continuous E2 plus intermittent NGM 180 microg (n = 219), and an oral 2-mg dose of continuous E2 plus continuous norethisterone acetate (NETA) 1 mg (n = 217) on blood lipids and lipoproteins in postmenopausal women.

BACKGROUND

The present study was undertaken because some progestins have adverse effects on lipid profiles, thereby negating the favorable effects of estrogens.

METHODS

This was a multicenter, randomized, parallel-group trial that focused primarily on the 2 marketed regimens--E2 1 mg/NGM 90 microg and E2/NETA. Both subjects and investigators were blinded to the intermittent regimens; the continuous combined regimen was administered open-label. After a minimum 12-hour overnight fast, blood samples were collected at baseline and during months 7 and 12 to determine lipid and lipoprotein concentrations using validated methods.

RESULTS

E2 1 mg/NGM 90 microg was associated with significant (ie, the 95% CI did not include 0) increases in high-density lipoprotein cholesterol (HDL-C) (6.8% [95% CI = 4.7%, 9.0%] and 4.8% [2.3%, 7.2%] at months 7 and 12, respectively) and high-density lipoprotein 2 cholesterol (HDL2-C) (10.8% [6.2%, 15.3%] and 24.1% [18.9%, 29.4%]) concentrations, and decreases in total cholesterol (-7.7% [-9.0%, -6.3%] and -9.2% [-10.5%, -7.9%]), low-density lipoprotein cholesterol (-14.3% [-16.3%, -12.4%] and -14.9% [-16.7%, -13.2%]), and lipoprotein(a) (-30.6% [-41.4%, -20.0%] at month 12) concentrations. A significant difference (P < 0.001 by analysis of variance) between the E2 1-mg/NGM 90-microg and NETA regimens was seen for HDL-C and HDL2-C concentrations, which were elevated in subjects receiving E2 1 mg/NGM 90 microg but reduced (-9.1% [-11.1%, -7.1%] and -12.3% [-14.3%, -10.3%] for HDL-C at months 7 and 12, respectively; -14.2% [-18.0%, -10.4%] and -2.5% [-7.8%, +2.8%] for HDL2-C at months 7 and 12, respectively) in those receiving E2/NETA.

CONCLUSIONS

In the present study, continuous E2 1 mg/NGM 90 microg was associated with beneficial effects on lipids and lipoproteins in healthy postmenopausal women, effects that were greater at least for HDL-C and HDL2-C than those observed with continuous combined E2/NETA. The applicability of the study results to women with preexisting cardiovascular disease or dyslipidemia, or those who are overweight, remains to be investigated.