Conjugated estrogen

Conjugated estrogens, or conjugated equine estrogens (CEEs), are blended equine estrogens, which may include estrone sulfate, equilin sulfate, and equilenin sulfate. CEEs are used clinically in hormone replacement therapy, with marketed products including both natural preparations isolated from the urine of pregnant mares (brand names Premarin) as well as fully synthetic replications of the natural preparations (brand names Cenestin, Enjuvia, Congest, and C.E.S.). Prempro and Premphase are combination formulations of natural CEEs with medroxyprogesterone acetate.