with taurine (to give tauromuricholic acids which are the main forms), or with glycine (to give glycomuricholic acids) takes place in the liver before secretion.

The enzyme responsible for the 6-hydroxylation reactions forming muricholates in mice is the cytochrome P450 Cyp2c70. This produces ?-muricholic acid from chenodeoxycholic acid, and ?-muricholic acid from ursodeoxycholic acid.