Digitalis; ketoconazole & other strong P450 3A inhibitors including atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, voriconazole. May interfere absorption w/ cholestyramine (cap only). Increased risk of hypercalcemia w/ prescription-based phosphate or vit D-related medicinal products & Ca-containing prep or thiazide diuretics. Mg- & Al-containing prep (eg, antacids, phosphate-binders).