Women are often counseled that “perfect” use of hormonal contraception results in greater effectiveness than “typical” use, which encompasses human error in drug dosing and administration. However, a small percentage of women may become pregnant even with “perfect” use of highly effective methods. Researchers at the University of Colorado have turned to the field of pharmacogenetics to explore this variation in response and their findings were recently published in Obstetrics and Gynecology.
The study enrolled 370 healthy, reproductive-aged women in the United States who were currently using etonogestrel (ENG) contraceptive implants. ENG levels were measured in women at baseline and linear modeling was used to identify three generic variants associated with serum ENG levels. Of these variants, one was associated with increased metabolism of ENG (27% of women with the variant had concentrations insufficient for suppression of ovulation), leading the researchers to hypothesize that it may lead to increased metabolism of all steroid hormones. Read more here.