|Systematic (IUPAC) name|
|(8S,9R,10S,11S,13S,14S,16R,17R)-9- Fluoro-11,17-dihydroxy-17-(2-hydroxyacetyl)-10,13,16-trimethyl-6,7,8,9,10,11,12,13,14,15,16,17- dodecahydro-3H-cyclopenta[a]phenanthren-3-one|
|Routes||Oral, IV, IM, SC and IO|
|ATC code||A01 C05, D07, D10, H02, R01, S01,S02, S03|
|Mol. mass||392.461 g/mol|
|(what is this?)|
Dexamethasone is a potent synthetic member of the glucocorticoid class of steroid drugs that has anti-inflammatory and immunosuppressant effects. It is 25 times more potent than cortisol in its glucocorticoid effect, while having minimal mineralocorticoid effect.
It is on the World Health Organization's List of Essential Medicines, a list of the most important medications needed in a basic health system.
Dexamethasone is used to treat many inflammatory and autoimmune conditions, such as rheumatoid arthritis and bronchospasm. Idiopathic thrombocytopenic purpura, a decrease in numbers of platelets due to an immune problem, responds to 40 mg daily for four days; it may be administered in 14-day cycles. It is unclear whether dexamethasone in this condition is significantly better than other glucocorticoids.
It is also given in small amounts before and/or after some forms of dental surgery, such as the extraction of the wisdom teeth, an operation which often leaves the patient with puffy, swollen cheeks.
It is useful to counteract allergic anaphylactic shock, if given in high doses.
Dexamethasone is used in transvenous screw-in cardiac pacing leads to minimize the inflammatory response of the myocardium. The steroid is released into the myocardium as soon as the screw is extended and can play a significant role in minimizing the acute pacing threshold due to the reduction of inflammatory response. The typical quantity present in a lead tip is less than 1.0 mg.
Dexamethasone is often administered before antibiotics in cases of bacterial meningitis. It then acts to reduce the inflammatory response of the body to the bacteria killed by the antibiotics (bacterial death releases proinflammatory mediators that can cause a response which is harmful to the patient), thus improving prognosis and outcome.
Cancer patients undergoing chemotherapy are given dexamethasone to counteract certain side effects of their antitumor treatment. Dexamethasone can augment the antiemetic effect of 5-HT3 receptor antagonists, such as ondansetron.
In brain tumors (primary or metastatic), dexamethasone is used to counteract the development of edema, which could eventually compress other brain structures. It is also given in cord compression, where a tumor is compressing the spinal cord.
Dexamethasone is also used as a direct chemotherapeutic agent in certain haematological malignancies, especially in the treatment of multiple myeloma, in which dexamethasone is given alone or in combination with other chemotherapeutic drugs, including most commonly with thalidomide (Thal-dex), lenalidomide, bortezomib (Velcade, Vel-dex), or a combination of adriamycin (doxorubicin) and vincristine or velcade/revlimid/dexamethasone.
Dexamethasone may be given to women at risk of delivering prematurely to promote maturation of the fetus' lungs. This has been associated with low birth weight, although not with increased rates of neonatal death.
Dexamethasone is used in the treatment of high-altitude cerebral edema, as well as pulmonary edema. It is commonly carried on mountain-climbing expeditions to help climbers deal with altitude sickness.
Dexamethasone has been used as an off-label prenatal treatment for the symptoms of congenital adrenal hyperplasia (CAH) in female fetuses. CAH causes a variety of physical abnormalities, notably ambiguous genitalia in girls. Early prenatal CAH treatment has been shown to reduce some CAH symptoms, but it does not treat the underlying congenital disorder.
A small clinical trial found long-term effects on verbal working memory among the small group of children treated prenatally, but the small number of test subjects means the study cannot be considered definitive. Administration of prenatal dexamethasone has been the subject of controversy over issues of informed consent and because treatment must predate a clinical diagnosis of CAH in the female fetus.
The exact incidence of the adverse effects of dexamethasone are not available, hence estimates have been made as to the incidence of the adverse effects below based on the adverse effects of related corticosteroids and on available documentation on dexamethasone.
- Increased appetite
- Weight gain
- Impaired skin healing
- Increased risk of infection
- Raised intraocular pressure
- Cataract (in cases of long-term treatment it occurs in about 10% of patients)
- Adrenal suppression
- Growth stunting (in children)
- Cushing's syndrome
- Peptic ulcer
- Diabetes mellitus type 2
- Pancreatitis (inflammation of the pancreas)
- Sodium and water retention
- Abdominal distention
- Corneal or scleral thinning
- Skin atrophy
- Psychological dependence
- Vertebral collapse
- Oesophageal ulcer
- Intracranial hypertension (long-term treatment)
- Facial plethora
- Muscular atrophy
- Nitrogen depletion due to protein catabolism
- Allergic reactions including anaphylaxis
Sudden withdrawal after long-term treatment with corticosteroids can lead to:
- Uncontrolled infections
- Known hypersensitivity to dexamethasone
- Cerebral malaria
- Systemic fungal infection
- Concurrent treatment with live virus vaccines (including smallpox)
Known drug interactions include:
- Inducers of hepatic microsomal enzymes such as barbiturates, phenytoin, and rifampicin can reduce the half-life of dexamethasone.
- Cotreatment with oral contraceptives can increase its volume of distribution.
To synthesize dexamethasone, 16β-methylprednisolone acetate is dehydrated to the 9,11-dehydro derivative. This is then reacted with a source of hypobromite, such as basic N-bromosuccinimide, to form the 9α-bromo-11β-hydrin derivative, which is then ring-closed to an epoxide. A ring-opening reaction with hydrogen fluoride in tetrahydrofuran gives dexamethasone.
Dexamethasone is given in legal Bangladeshi brothels to prostitutes not yet of legal age, causing weight gain aimed at making them appear healthier and older to customers and police.
Combined with marbofloxacin and clotrimazole, dexamethasone is available under the name Aurizon, CAS number 115550-35-1, and used to treat difficult ear infections, especially in dogs. It can also be combined with trichlormethiazide to treat horses with swelling of distal limbs and general bruising.
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