Coadministration has not been studied. Metabolism of vitamin D to active metabolites occurs in the liver and kidneys, and is thought to involve CYP3A4 and CYP24A1. There is little potential for an interaction with dolutegravir via modulation of, or competition for, metabolic pathways. No interaction is expected with vitamin D when given as a single agent (i.e. not with calcium or in a multivitamin preparation) or as an injection. However, colecalciferol can be found in multivitamin preparations. Simultaneous coadministration of a multivitamin preparation decreased dolutegravir exposure by ~33%. Dolutegravir should be administered 2 hours before or 6 hours after medications containing polyvalent cations, such as multivitamin preparations. Medicinal products that reduce dolutegravir exposure (e.g. multivitamins) should be avoided in the presence of integrase class resistance.