Sulfates are the foremost circulating conjugates of ethinyl estradiol and glucuronides predominate in urine. The first oxidative metabolite is 2-hydroxy ethinyl estradiol, fashioned via the CYP3A4 isoform of cytochrome P450. Component of the main-pass metabolism of ethinyl estradiol is considered to arise in gastrointestinal mucosa. Ethinyl estradi