Tramadol HCl: Life-threatening interactions on CNS, resp & CV function w/ MAOIs. Elevated INR w/ coumarin derivatives (eg, warfarin). Reduced analgesic effect of pure agonist in mixed agonists/antagonists opioid receptors (eg, buprenorphine, nalbuphine, pentazocine). Risk of convulsions w/ SSRIs, SNRIs, TCAs, antipsychotics & other seizure threshold-lowering medicinal product. Serotonin syndrome w/ serotonergic drugs. Increased risk of sedation, resp depression, coma & death w/ sedatives eg, benzodiazepines or related drugs. Potentiated CNS effects w/ other centrally depressants or alcohol. Reduced analgesic effect & shortened duration of action w/ carbamazepine (enzyme inducer). Increased dosing requirement w/ ondansetron. Possible inhibition of metabolism w/ CYP3A4 inhibitors (eg, ketoconazole, erythromycin). Dexketoprofen: Increased risk of GI ulcers & bleeding w/ other NSAIDs (including COX-2 inhibitors) including high doses of salicylates; corticosteroids. Enhanced effects of anticoagulants eg, warfarin. Increased risk of haemorrhage w/ heparins; pentoxyfilline; thombolytics. Increased blood levels of lithium. Increased haematological toxicity of methotrexate. Increased toxic effects of hydantoins (including phenytoin) & sulphonamides. Reduced effects of diuretics & antihypertensives. Risk of further renal deterioration w/ ACE inhibitors, AIIA or antibacterial aminoglycosides in patients w/ compromised renal function. Hyperkalaemia w/ K-sparing diuretics. Risk of increased red cell line toxicity w/ zidovudine. Increased hypoglycaemic effect of sulfonylureas. Decreased effects of β-blockers. Enhanced nephrotoxicity of cyclosporin & tacrolimus. Increased risk of GI bleeding w/ antiplatelet agents & SSRIs. Increased plasma conc w/ probenecid. Increased plasma conc of glycosides. May alter efficacy of mifepristone. Increased plasma urea nitrogen & creatinine w/ tenofovir. Increased risk of GI toxicity w/ deferasirox. Decreased elimination of pemetrexed.