In women with a specific set of genes, hormonal contraceptives may not work effectively. According to a study conducted by American gynecologists, in 5% of women, a progestin, the active hormone of such drugs, is divided more rapidly than usual. As a result, the effectiveness of contraceptives decreases.
Hormonal contraceptives are made on the basis of progestogens – synthetic analogues of the progestin, and estrogen, one of the female sex hormones, is often added to them. The progestogens act because of a variety of effects at once – from the blockage of the ovulation to the change of the uterus and the fallopian tubes, so they are included in hormone pills for permanent use and in pills for contraception. # 39; emergency. Even the hormonal implants that release a small amount of hormones from a capsule sewn into the forearm are made based on progestogens – it can be said that in practice the "progestins" and "hormonal contraception" are often the same.
For their study, doctors at the University of Colorado attracted 350 healthy women with an implanted implant based on one of the progestins, etonogestrel. Scientists took blood samples from all participants to determine the level of this hormone. Furthermore, the scientists analyzed their genotype. This allowed us to determine that due to increased activity of one of the genes, CYP3A7, the concentration of the synthetic hormone decreases and, therefore, the effectiveness of hormonal contraception should decrease.
However, scientists have not measured the Pearl Index, ie the frequency of unwanted pregnancies when using a particular contraceptive. There were 18 women who showed greater CYP3A7 activity, which is too small for statistically reliable results. However, the authors indicate that the effect they have recorded may have clinical significance.
"When a woman says she is pregnant while using contraception, we often believe that this is somehow related to her negligence," the press service of the university mentions the lead author of the study, Aaron Lazorwitz. "However, these new data indicate that we should listen to patients and consider that something could be the cause of their genes."
The CYP3A7 gene is responsible for protein synthesis from a family of cytochromes, chemically active molecules. Many of the cytochromes play a key role both in normal metabolism and in neutralizing toxins. Specifically, CYP3A7 can process including progestogens. Usually, the researchers write, this protein is synthesized only during fetal development, but a certain variant of this gene (allele, as the genetics say) leads to the fact that CYP3A7 remains active even in adulthood.
The new discovery, as the authors say, will allow a more efficient selection of contraceptives and other drugs. Progestins are prescribed in numerous other cases – from hormone therapy during menopause to the treatment of a number of malignant tumors, and the genotype analysis of patients each year becomes increasingly accessible. Contraception and therapy may be selected in the near future after a relatively simple test.