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Dexamethasone
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9-Fluoro-11β,17,21-trihydroxy-16a-
methylpregna-1,4-diene-3,20-dione
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CAS number
50-02-2
| ATC code
A01AC02, C05AA09, D07AB19, H02AB02, R01AD03, S01BA01, S02BA06, S03BA01
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| Chemical formula
| C22H29FO5
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| Molecular weight
| 392.464
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| Bioavailability
| ?
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| Metabolism
| ?
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| Elimination half-life
| ?
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| Excretion
| ?
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| Pregnancy category
| ?
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| Legal status
| ?
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| Routes of administration
| ?
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Dexamethasone is a synthetic member of the glucocorticoid class of hormones. It acts as an anti-inflammatory and immunosuppressant. Its potency is about 40 times that of hydrocortisone.
Therapeutic use
Dexamethasone is used to treat many inflammatory and autoimmune conditions. It is also given to cancer patients undergoing chemotherapy, to counteract certain side-effects of their antitumor treatment. In certain forms of brain disease, e.g. brain tumours or secondaries, dexamethasone is used to counteract the development of edema, which would eventually compress other brain structures. It is present in certain eye drops.
Diagnostic use
Dexamethasone is also used in a diagnostic context, namely in its property to suppress the natural pituitary-adrenal axis.
Patients presenting with clinical signs of glucocorticoid excess (Cushing's syndrome) are generally diagnosed by a 24h urine collection for cortisol or by a dexamethasone suppression test. During the latter, the response of the body to a high dose of glucocorticoids is monitored. Various forms are performed. In the most common form, a patient takes a nighttime dose of either 1 or 4 mg of dexamethasone, and the serum cortisol levels are measured in the morning. If the levels are relatively high (over 5 μg/dl or 150 nmol/l), then the test is positive and the patient has an autonomous source of either cortisol or ACTH, indicating Cushing's disease. Longer versions rely on urine collections on oral dexamethasone over various days.
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