Sulfates are the most important circulating conjugates of ethinyl estradiol and glucuronides predominate in urine. The key oxidative metabolite is 2-hydroxy ethinyl estradiol, shaped via the CYP3A4 isoform of cytochrome P450. A part of the initial-move metabolism of ethinyl estradiol is thought to manifest in gastrointestinal mucosa. Ethinyl estrad