Paracetamol: Dosage reduction may be required w/ anticoagulants (warfarin). Increased absorption w/ substances that increase gastric emptying (eg, metoclopramide). Decreased absorption w/ substances that decrease gastric emptying (eg, propantheline, antidepressants w/ anticholinergic properties, & narcotic analgesics). May increase plasma conc of chloramphenicol. Increased risk of toxicity w/ other potentially hepatotoxic drugs or drugs that induce liver microsomal enzymes eg, alcohol & anticonvulsant agents. Altered excretion & plasma conc w/ probenecid. Reduced absorption w/ cholestyramine if given w/in 1 hr of paracetamol. Severe hepatotoxicity at therapeutic doses or moderate overdoses of paracetamol w/ INH alone or w/ other drugs for TB. Severe hepatotoxicity w/ zidovudine & co-trimoxazole. Ibuprofen: Interference w/ INR stability & increased risk of severe bleeding w/ anticoagulants, including warfarin. May decrease renal clearance & increase plasma conc of lithium. May reduce the anti-hypertensive effect of ACE inhibitors, β-blockers & diuretics; may cause natriuresis & hyperkalemia in patients under these treatments. Reduced methotrexate clearance. May increase plasma levels of cardiac glycosides. Increased risk of GI bleeding w/ corticosteroids. Prolonged bleeding time w/ zidovudine. May interact w/ probenecid, antidiabetic medicines & phenytoin; tacrolimus, ciclosporin, sulphonylureas & quinolone antibiotics. Increased adverse effects w/ acetylsalicylic acid.