Reduced antidiabetic effects. Intensified coumarin derivative effects. Effects influenced by PIs eg, ritonavir, indinavir, lopinavir; phenytoin. Inhibited absorption w/ ion exchange resins eg, cholestyramine, colestipol. Decreased effect w/ Al-, Fe- & Ca-containing drugs. Elevated FT4
fraction w/ salicylates, dicumarol, high-dose furosemide (250 mg), clofibrate. Hypothyroidism &/or reduced control of hypothyroidism w/ orlistat. Decreased absorption w/ sevelamer. Decreased efficacy by tyrosine kinase inhibitors eg, imatinib, sunitinib; sertraline, chloroquine/proguanil. Inhibited peripheral T4
conversion w/ propylthiouracil, glucocorticoids, β-sympatholytics, amiodarone, iodine-containing contrast media. Increased hepatic clearance by barbiturates or carbamazepine. Increased need of levothyroxine in women using oestrogen-containing contraceptives or post-menopausal women under hormone-replacement therapy. Decreased intestinal absorption w/ soy-containing compd.