A randomized comparative open study of the effects of two oral contraceptives, Triphasil and Ortho 7/7/7, on lipid metabolism.

This study assessed serum lipid, lipoprotein and apolipoprotein changes during one year in 3 groups of nonsmoking women: 1) Triphasil(R); 2) Ortho(R) 7/7/7; 3) Controls. Both oral contraceptives contain the estrogen, ethinyl estradiol(EE), in combination with a progestin in three different ratios during each cycle. The progestin in Triphasil is d-norgestrel, as the dl-racemate norgestrel (NG), whereas that in Ortho 7/7/7 is norethindrone(NE). Total plasma triglycerides were elevated significantly from baseline (p < 0.001) with Ortho 7/7/7 at 3, 6 and 12 months, but only at 3 months with Triphasil, p = 0.047. Triglycerides were elevated in the LDL fraction with Ortho 7/7/7 at 3 months (p = 0.001), 6 months (p = 0.018) and 12 months (p = 0.010). In contrast, LDL triglycerides were not significantly elevated with Triphasil. Similarly, IDL triglycerides were elevated only in the Ortho 7/7/7 group at 6 months (p = 0.002) and 12 months (p = 0.001). Plasma cholesterol was elevated only in the Ortho 7/7/7 group at 3, 6 and 12 months with p values of 0.009, 0.005 and 0.010, respectively. Cholesterol in the LDL fraction was elevated with Ortho 7/7/7 at 12 months (p = 0.002). Plasma apolipoprotein B (apo B) increased at least 24% from baseline for both the Triphasil and Ortho 7/7/7 groups at 3 and 12 months (p < 0.001). However, at 6 months, apolipoprotein B increased only 17.7% (p = 0.008) with Triphasil compared to 29.7% (p < 0.001) with Ortho 7/7/7 at 6 months. Apo B was increased (p < 0.001) in LDL with Triphasil at 3 months only, whereas LDL apo B was increased at 3, 6 and 12 months with Ortho 7/7/7 (p < 0.001, p = 0.020 and p = 0.012, respectively). Apo B increased dramatically in the IDL fraction of both oral contraceptive user populations, with the range of increases being between 48% and 87% during the year (p < 0.001 at all times). Significant elevations in VLDL apo B ranged from 71% to 106% (p < 0.001) with Triphasil and from 42.4% (p < 0.005) to 72.6% (p < 0.001) with Ortho 7/7/7. In conclusion, norethindrone- and dl-norgestrel-formulations have divergent effects on several components of plasma lipoprotein and lipid metabolism, but both products increase plasma and IDL apo B.