Effects of oral contraceptive combinations containing levonorgestrel or desogestrel on serum proteins and androgen binding.

The effects of the oral contraceptive combinations 0.125 mg Org 2969 (desogestrel) (13-ethyl-11-methylene-18,19-dinor-17alpha-pregn-4-en-20-yn-17-ol) + 0.05 mg ethinyloestradiol (EE) and 0.125 mg levonorgestrel + 0.05 mg EE on serum sex-hormone-binding globulin (SHBG), ceruloplasmin, transcortin and ratio free testosterone over total testosterone (percentage free testosterone) and ratio free 5alpha-dihydrotestosterone over total 5alpha-dihydrotestosterone (percentage free 5alpha-dihydrotestosterone) were compared in healthy female volunteers. Treatment was randomly distributed over the volunteers; 11 women received Org 2969 + EE and 11 women received levonorgestrel + EE. These combinations induced similar increases in transcortin levels (115 and 140%) and ceruloplasmin levels (115 and 123%) after 3 months of treatment. However, the combination Org 2969 + EE induced a substantial increase (213%) in SHBG capacity after 3 months of treatment, whereas a smaller increase (80%) was observed with levonorgestrel + EE. A return to pretreatment values was observed 2 months after termination of treatment for all parameters. The difference in the effects of both preparations oh SHBG was statistically significant and can be best explained by a difference in the androgenicity of the progestogens. A good correlation was free testosterone and the reciprocal value of the percentage free 5 alpha-dihydrotestosterone. These results confirm that SHBG is the major regulator of the biologically active free androgen fraction in women before, during and after combined oral contraceptive treatment.