A corticosteroid drug prescribed as a nasal spray to relieve nasal congestion caused by allergic rhinitis, as eye drops in the treatment of iritis, and as eardrops in the treatment of otitis externa. It is given in tablet form or injected to treat severe asthma and other inflammatory disorders in order to reduce inflammation of the brain due, for example, to head injury. It may be injected into an inflamed joint to relieve the symptoms of osteoarthritis.
The nasal spray may cause nosebleeds; eye drops may cause irritation. Prolonged use or high doses of tablet may cause adverse effects common to the corticosteroids.
A CORTICOSTEROIDS derivative. As an antiin?ammatory agent it is approximately 30 times as e?ective as cortisone and eight times as e?ective as prednisolone. On the other hand, it has practically none of the salt-retaining properties of cortisone.
n. a *corticosteroid drug used principally to treat severe allergies, eye inflammation, rheumatic and other inflammatory conditions, and congenital adrenal hyperplasia. Side-effects include sodium and fluid retention, muscle weakness, convulsions, vertigo, headache, and hormonal disturbances (including menstrual irregularities). In the form of an implant into the vitreous humour, it is also used to treat oedema associated with *retinal vein occlusion. Dexamethasone is also used in a series of tests for Cushing’s syndrome (see dexamethasone suppression tests).
(DSTs) tests based on the principle that appropriate doses of *dexamethasone can suppress the output of cortisol from the adrenal glands in the normal state and that this ability is reduced or lost in *Cushing’s syndrome. In the overnight DST 1 mg of dexamethasone is administered at midnight and the serum cortisol level is measured at 9.00 am the next morning. Failure to suppress cortisol output may indicate Cushing’s syndrome but also occurs in patients with obesity and depressive illness. In the low-dose DST (0.5 mg dexamethasone every 6 hours for 48 hours), cortisol suppression occurs in patients with obesity and depression but not in those with Cushing’s syndrome. In the high-dose DST (2 mg dexamethasone every 6 hours for 48 hours), cortisol is suppressed in patients with Cushing’s disease (in which excess amounts of ACTH are secreted by the pituitary gland) but not in those with Cushing’s syndrome due to other causes. Although the low- and high-dose tests are unreliable, all three tests should be performed to aid the diagnosis of Cushing’s syndrome.... dexamethasone suppression tests
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