Dose and duration effects of oestradiol valerate on serum apolipoproteins A1 and B

Abstract

The serum levels of apolipoprotein A1 (ApoA1) and apolipoprotein B (ApoB) were assessed by electroimmunoassay in 19 bilaterally oophorectomised women before and after treatment with 2 and 4 mg oestradiol valerate (E 2V) daily. The first part of the study was conducted in accordance with an open cross-over design. The levels of ApoA1 were found to have increased after the 6-week treatment periods using each of those dosages, the increase being most pronounced after treatment with 4 mg E 2V. ApoB concentrations decreased at both dosage levels. The serum levels of total (TC) and free cholesterol (FC) and phospholipids (PL) in the high-density lipoprotein (HDL) fraction correlated positively with the serum levels of ApoA1 before treatment. The correlations between serum ApoA1 and HDL-PL levels persisted after both dosage regimens. Before and after treatment with 2 mg E 2V, serum ApoB levels correlated positively with the levels of all lipid components in the low-density lipoprotein (LDL) fraction. After 4 mg E 2V, serum ApoB levels correlated positively with LDL-PL and LDL-TC levels. On conclusion of the cross-over, in order to assess the effects of the duration of therapy, the women were followed up for a further period of 3 mth, during which ten were given 2 mg and the other nine 4 mg of E 2V daily. The increased levels of ApoA1 and the decreased levels of ApoB seen after the cross-over study were not found to have altered after this treatment-duration evaluation. The data indicate that 2 and 4 mg daily doses of E 2V have parallel effects on both the lipid and protein components of the lipoprotein fraction, producing a lipoprotein pattern with possible beneficial clinical implications.