What is dexamethasone, and how does it work (mechanism of action)?
Dexamethasone is a synthetic (man-made) corticosteroid. Corticosteroids are naturally-occurring chemicals produced by the adrenal glands located above the kidneys. Corticosteroids affect the function of many cells within the body and suppress the immune system. Corticosteroids also block inflammation and are used in a wide variety of inflammatory diseases affecting many organs. The FDA approved dexamethasone in October 1958.
What brand names are available for dexamethasone?
Is dexamethasone available as a generic drug?
Do I need a prescription for dexamethasone?
What are the uses for dexamethasone?
A major UK study of almost 7,000 patients released in June 2020 made dexamethasone the standard of care for COVID-19 patients with symptoms severe enough to need oxygen. Researchers showed dexamethasone can save the life of one in eight patients on ventilators and one in 25 patients on supplemental oxygen (not intubated), according to Medscape Medical Reference.
Dexamethasone is used for reducing inflammation in many conditions. Some examples include:
- rheumatoid arthritis,
- systemic lupus,
- acute gouty arthritis,
- psoriatic arthritis,
- ulcerative colitis, and
- Crohn's disease.
Severe allergic conditions that fail to respond to other treatments also may respond to dexamethasone. Examples include:
- bronchial asthma,
- allergic rhinitis,
- drug-induced dermatitis, and
- contact and atopic dermatitis.
Chronic skin conditions treated with dexamethasone include:
- dermatitis herpetiformis,
- severe psoriasis, and
- severe seborrheic dermatitis.
Chronic allergic and inflammatory conditions of the uvea, iris, conjunctiva, and optic nerves of the eyes also are treated with dexamethasone.
Dexamethasone is used in the treatment of cancers of the white blood cells (leukemias), and lymph gland cancers (lymphomas). Blood diseases involving destruction by the body's own immune system of platelets are also treated with dexamethasone, disease like idiopathic thrombocytopenic purpura, and red blood cells (autoimmune hemolytic anemia. Other miscellaneous conditions treated with dexamethasone include thyroiditis and sarcoidosis.
Finally, dexamethasone is used as replacement therapy in patients whose adrenal glands are unable to produce sufficient amounts of corticosteroids.
Many of the medical problems treated by this drug are “off label”; that is, its use is not sanctioned or approved by the FDA.
What are the side effects of dexamethasone?
Side effects of dexamethasone depend on the dose, the duration, and the frequency of administration. Short courses of dexamethasone usually are well tolerated with few and mild side effects. Long term, high dose dexamethasone usually will produce predictable and potentially serious side effects. Whenever possible, the lowest effective dose of dexamethasone should be used for the shortest possible length of time to minimize side effects. Alternate day dosing also can help reduce side effects.
Side effects of dexamethasone and other corticosteroids range from mild annoyances to serious irreversible damage. Side effects include:
- fluid retention,
- weight gain,
- high blood pressure,
- loss of potassium,
- increase in serum glucose levels (especially in diabetics),
- muscle weakness,
- puffiness of and hair growth on the face,
- thinning and easy bruising of the skin,
- peptic ulceration,
- worsening of diabetes,
Other side effects include:
- irregular menses,
- growth retardation in children,
- convulsions, and
- psychic disturbances.
Psychic disturbances include:
- mood swings,
- personality changes, and
- even psychotic behavior.
Prolonged use of dexamethasone can depress the ability of the body's adrenal glands to produce corticosteroids. Abruptly stopping dexamethasone in these individuals can cause symptoms of corticosteroid insufficiency, with accompanying nausea, vomiting, and even shock. Therefore, withdrawal of dexamethasone usually is accomplished by gradually reducing the dose. Gradually tapering dexamethasone not only minimizes the symptoms of corticosteroid insufficiency but also reduces the risk of an abrupt flare of the disease under treatment.
Dexamethasone and other corticosteroids can mask signs of infection and impair the body's natural immune response that is important in fighting infection. Patients on corticosteroids are more susceptible to infections and can develop more serious infections than individuals not receiving corticosteroids. For example, chickenpox and measles viruses can produce serious and even fatal illnesses in patients on high doses of dexamethasone. Live virus vaccines, such as the smallpox vaccine, should be avoided in patients taking high doses of dexamethasone, since even vaccine viruses may cause disease in these patients. Some infectious diseases, such as tuberculosis (TB) and malaria, can remain dormant in a patient for years. Dexamethasone and other corticosteroids can reactivate dormant infections. Patients with dormant tuberculosis may require treatment of the TB while undergoing corticosteroid treatment.
By interfering with the patient's immune response, dexamethasone can impede the effectiveness of vaccinations. Dexamethasone can also interfere with the tuberculin (TB) skin test and cause falsely negative results in patients with dormant tuberculosis infection.
Dexamethasone impairs calcium absorption and new bone formation. Patients on prolonged treatment with dexamethasone and other corticosteroids can develop osteoporosis and an increased risk of bone fractures. Supplemental calcium and vitamin D are encouraged to slow this process of bone thinning. It has been demonstrated in some groups of patients treated with steroids that the loss of bone may be prevented by treatment with bisphosphonate drugs, for example, alendronate (Fosamax).
In rare individuals, the destruction of large joints can occur while undergoing treatment with dexamethasone or other corticosteroids. These patients experience severe pain in the involved joints and can require joint replacements. The reason behind such destruction is not clear.
The term arthritis refers to stiffness in the joints.
What is the dosage for dexamethasone?
Dosage requirements of corticosteroids vary greatly among individuals and the diseases being treated. In general, the lowest possible effective dose is used. The initial oral dose is 0.75 mg to 9 mg daily depending on the disease. The initial dose should be adjusted based on response. Corticosteroids given in multiple doses (2 to 4 times daily) throughout the day are more effective but also are more toxic as compared with the same total daily dose given once daily, or every other day.
Which drugs or supplements interact with dexamethasone?
Corticosteroids may increase or decrease the effect of blood thinners, for example, warfarin (Coumadin). Blood clotting should be monitored and the dose of blood thinner adjusted in order to achieve the desired level of blood thinning when patients receiving blood thinners are begun on corticosteroids, including dexamethasone.
Phenobarbital, ephedrine, phenytoin (Dilantin), and rifampin (Rifadin, Rimactane) may increase the breakdown of corticosteroids by the liver, resulting in lower blood levels and reduced effects. Therefore, the dose of corticosteroid may need to be increased if treatment with any of these agents is begun.
Mifepristone may reduce the action of corticosteroids via unknown mechanisms. Dexamethasone may decrease blood levels of mifepristone. Mifepristone should not be combined with steroids.
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Is dexamethasone safe to take if I’m pregnant or breastfeeding?
INFORMATION Use of dexamethasone in pregnant women has not been adequately studied. When corticosteroids are given systemically (orally, intramuscularly, or intravenously) to pregnant animals fetal abnormalities occurred.
Dexamethasone has not been adequately evaluated in nursing mothers. Corticosteroids appear in breast milk and may cause side effects in infants.
What else should I know about dexamethasone?
What preparations of dexamethasone-decadron-dexpak are available?
Tablets: 0.5, 0.75, 1, 1.5, 2, 4, and 6 mg. Elixir/Solution: 0.5 mg /5 mL. Oral Concentrate: 1 mg/ml and for injection (IV, IM, intra-articular, intralesional or into tissue), 4mg/ml and 10mg/ml.
How should I keep dexamethasone-decadron-dexpak stored?
Dexamethasone should be stored at 20 C – 25 C (68 F – 77 F) and not frozen.