Calcitriol is a hydroxycalciol that is calcidiol in which the pro-S hydrogen of calcidiol is replaced by a hydroxy group. It is the active form of vitamin D3, produced fom calciol via hydoxylation in the liver to form calcidiol, which is subsequently oxidised in the kidney to give calcitriol. It has a role as a bone density conservation agent, an antipsoriatic, an immunomodulator, an antineoplastic agent, a calcium channel modulator, a nutraceutical, a calcium channel agonist, a metabolite, a hormone, a human metabolite and a mouse metabolite. It is a hydroxycalciol, a member of D3 vitamins and a triol.