Dexamemet Drug Interactions

Aspirin should be used cautiously in conjunction with corticosteroids in hypoprothrombinaemia. The renal clearance of salicylates is increased by corticosteroids and therefore salicylate dosage should be reduced along with steroid withdrawal.
As phenytoin, barbiturates, ephedrine, rifabutin, carbamazepine, rifampicin and aminoglutethimide may enhance the metabolic clearance of corticosteroids, resulting in decreased blood levels and reduced physiological activity, the dosage may have to be adjusted. These interactions interfere with dexamethasone suppression tests which should be interpreted with caution during administration of these drugs.
False-negative results in the dexamethasone suppression test in patients being treated with indometacin have been reported.
The efficacy of coumarin anticoagulants may be changed by concurrent corticosteroid treatment. The prothrombin time should be checked frequently in patients who are receiving corticosteroids and coumarin anticoagulants at the same time, in order to avoid spontaneous bleeding.
The desired effects of hypoglycaemic agents (including insulin) are antagonised by corticosteroids. When corticosteroids are administered concomitantly with potassium-depleting diuretics, patients should be observed closely for development of hypokalaemia.
Corticosteroids may affect the nitroblue tetrazolium test for bacterial infection and produce false negative results.
Antiretroviral protease inhibitors (ritonavir, darunavir, indinavir, lopinavir, saquinavir and efavirenz) are metabolised by CYP3A. Medicinal products that induce CYP3A activity, such as dexamethasone, may increase the clearance of medicines metabolised by CYP3A, resulting in lowered plasma concentrations.
Certain antiretroviral protease inhibitors (ritonavir, indinavir) may also be inhibitors of CYP3A themselves and as a result may increase the plasma concentration of dexamethasone.