Interactions : אינטראקציות

4.5. Interaction with other medicinal products and other forms of interaction

Phenytoin, phenobarbital, epinephrine and rifampicin may enhance the metabolic clearance of corticosteroids resulting in decreased blood levels and lessened pharmacological activity, thus requiring adjustment in corticosteroid dosage. These interactions may interfere with dexamethasone suppression tests which should be interpreted with caution during administration of these drugs.

Dexamethasone may reduce plasma levels of albendazole, with a possible inhibition of its effect through the induction of its hepatic metabolism.

Ephedrine may reduce plasma levels of dexamethasone, with a possible loss of anti- asthma control.

False negative results in the dexamethasone suppression test (DST) in patients being treated with indomethacin have been reported. Thus, results of the DST should be interpreted with caution in these patients.

Due to its hypoprothrombinemic activity, acetylsalicylic acid should be used with caution while on treatment with corticosteroids.

Prothrombin time should be checked frequently in patients being given coumarin anticoagulants or indandione derivatives with corticosteroids, since the latter alter anticoagulant response. Different studies have shown that, usually, they inhibit response tocoumarins, although there have been some studies where the response has been enhanced.

When corticosteroids are administered concomitantly with potassium-depleting diuretics, patients should be examined frequently to avoid the development of hypokalaemia.

Glucocorticoids may increase blood glucose concentration; the dosage of oral hypoglycemic agents or insulin or glucocorticoid may have to be adjusted when given concomitantly with any of these medicines.

Dexamethasone reduces the effects of antidiabetic agents and enhances the hypokalaemia induced by different diuretics and cardiotonic glycosides. The action of corticosteroids is increased when combined with estrogens and decreased when used with aminoglutethimide, carbamazepine, phenytoin or rifampicin. With indomethacin there is mutual potentiation of toxicity, and with isoniazid there is a reduction in the plasma levels of isoniazid.

Co-treatment with CYP3A inhibitors, including cobicistat-containing products, is expected to increase the risk of systemic side-effects. The combination should be avoided unless thebenefit outweighs the increased risk of systemic corticosteroid side- effects, in which case patients should be monitored for systemic corticosteroid side- effects.


This medicinal product may alter values in:
- Blood: increased cholesterol and glucose and decreased calcium, potassium and thyroidhormones.
- Urine: increase in glucose.
- Skin tests: tuberculin and allergy patch tests.