Enhanced metabolism w/ CYP3A4 inducers eg, barbiturates, phenytoin, primidone, rifampicin, rifabutin, aminoglutethimide, carbamazepine & other drugs that stimulate hepatic metabolism. Decreased metabolism w/ CYP3A4 inhibitors eg, antifungals (itraconazole, ketoconazole), antiemetics (aprepitant, fosaprepitant), immunosuppressants (ciclosporin, cyclophosphamide, tacrolimus), macrolides (clarithromycin, erythromycin, troleandomycin), HIV-PIs, diltiazem, grapefruit juice. Inhibition or induction of hepatic clearance w/ CYP3A4 substrates eg, Ca antagonists (mibefradil), H
2-receptor antagonists (cimetidine), contraceptives (ethinylestradiol/norethindrone) & Ca channel blockers (nifedipine, felodipine). Increased risk of hypokalemia w/ sympathomimetics eg, salbutamol, salmeterol, terbutaline, formoterol (at high doses of corticosteroids). Increased plasma conc w/ PIs (ie, indinavir & ritonavir). Decreased absorption w/ antacids. Alterations in plasma protein-binding & metabolism w/ OCs & estrogen. Increased risk of GI effects eg, GI bleeding & ulceration w/ aspirin or other NSAIDs. Enhanced or diminished effects of anticoagulants. Hypokalemia w/ K-depleting diuretics (eg, furosemide & thiazide) or carbonic anhydrase inhibitors (eg, acetazolamide); amphotericin B. Reduced effect w/ mifepristone. Acute myopathy w/ anticholinergics eg, neuromuscular blockers (at high doses of corticosteroids). Increased blood glucose conc & impaired glucose tolerance w/ insulin & oral antidiabetics. Increased risk of arrhythmias due to hypokalemia w/ digitalis glycosides. Diminished response to toxoids & live or inactivated vaccines (prolonged use of corticosteroids).