Dexamethasone


Dexamethasone is a type of corticosteroid medication. It is used in the treatment of many conditions, including rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, and along with antibiotics in tuberculosis. In adrenocortical insufficiency, it should be used together with a medication that has greater mineralocorticoid effects such as fludrocortisone. In preterm labor, it may be used to improve outcomes in the baby. It may be taken by mouth, as an injection into a muscle, or intravenously. The effects of dexamethasone are frequently seen within a day and last for about three days.
The long-term use of dexamethasone may result in thrush, bone loss, cataracts, easy bruising, or muscle weakness. It is pregnancy category C in the United States meaning use should be based on benefits being predicted to be greater than risks. In Australia, the oral use is category A, meaning it has been frequently used in pregnancy and not been found to cause problems to the baby. It should not be taken when breastfeeding. Dexamethasone has anti-inflammatory and immunosuppressant effects.
Dexamethasone was first made in 1957 by Philip Showalter Hench and was approved for medical use in 1961. It is on the World Health Organization's List of Essential Medicines. In 2017, it was the 321st most commonly prescribed medication in the United States, with more than one million prescriptions.

Medical uses

Anti-inflammatory

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.
Dexamethasone is commonly given as a treatment for croup in children, as a single dose can reduce the swelling of the airway to improve breathing and reduce discomfort.
It is injected into the heel when treating plantar fasciitis, sometimes in conjunction with triamcinolone acetonide.
It is useful to counteract allergic anaphylactic shock, if given in high doses.
It is present in certain eye drops – particularly after eye surgery – and as a nasal spray, and certain ear drops. Dexamethasone intravitreal steroid implants have been approved by the FDA to treat ocular conditions such as diabetic macular edema, central retinal vein occlusion, and uveitis. Dexamethasone has also been used with antibiotics to treat acute endophthalmitis.
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 may be administered before antibiotics in cases of bacterial meningitis. It acts to reduce the inflammatory response of the body to the bacteria killed by the antibiotics, thus reducing hearing loss and neurological damage.

Cancer

People with cancer undergoing chemotherapy are often given dexamethasone to counteract certain side effects of their antitumor treatments. Dexamethasone can increase the antiemetic effect of 5-HT3 receptor antagonists, such as ondansetron. The exact mechanism of this interaction is not well-defined, but it has been theorized that this effect may be due to, among many other causes, inhibition of prostaglandin synthesis, anti-inflammatory effects, immunosuppressive effects, decreased release of endogenous opioids, or a combination of the aforementioned.
In brain tumors, 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 hematological 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, lenalidomide, bortezomib, or a combination of doxorubicin and vincristine or bortezomib/lenalidomide/dexamethasone.

COVID-19

Dexamethasone treatment is recommended by the National Institutes of Health in the US, and by the National Health Service in the UK, for patients with COVID-19 who are mechanically ventilated or who require supplemental oxygen but are not mechanically ventilated. Dexamethasone has not been recommended in patients with COVID-19 who do not require supplemental oxygen or hospitalization, and the NIH recommends against such use.
The Infectious Diseases Society of America guideline panel suggests the use of glucocorticoids for patients with severe COVID-19 where severe is defined as patients with SpO2 ≤94% on room air, and those who require supplemental oxygen, mechanical ventilation, or ECMO. The IDSA recommends against the use of glucocorticoids for those with COVID-19 without hypoxemia requiring supplemental oxygen.

Endocrine

Dexamethasone is the treatment for the very rare disorder of glucocorticoid resistance.
In adrenal insufficiency and Addison's disease, dexamethasone is prescribed when the patient does not respond well to prednisone or methylprednisolone.
It can be used in congenital adrenal hyperplasia in older adolescents and adults to suppress ACTH production. It is typically given at night.

Pregnancy

Dexamethasone may be given to women at risk of delivering prematurely to promote maturation of the fetus' lungs. This administration, given from day to one week before delivery, has been associated with low birth weight, although not with increased rates of neonatal death.
Dexamethasone has also been used during pregnancy as an off-label prenatal treatment for the symptoms of congenital adrenal hyperplasia in female babies. CAH causes a variety of physical abnormalities, notably ambiguous genitalia. Early prenatal CAH treatment has been shown to reduce some CAH symptoms, but it does not treat the underlying congenital disorder. This use is controversial: it is inadequately studied, only around one in ten of the fetuses of women treated are at risk of the condition, and serious adverse events have been documented. Experimental use of dexamethasone in pregnancy for fetal CAH treatment was discontinued in Sweden when one in five cases suffered adverse events.
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.

High-altitude illnesses

Dexamethasone is used in the treatment of high-altitude cerebral edema, as well as high-altitude pulmonary edema. It is commonly carried on mountain-climbing expeditions to help climbers deal with complications of altitude sickness.

Nausea and vomiting

Intravenous dexamethasone is effective for prevention of nausea and vomiting in people who had surgery and whose post-operative pain was treated with long-acting spinal or epidural spinal opioids.
The combination of dexamethasone and a 5-HT3 receptor antagonist such as ondansetron is more effective than a 5-HT3 receptor antagonist alone in preventing postoperative nausea and vomiting.
Dexamethasone, when used as an anti emetic during surgery, does not appear to increase rates of wound infection and it is unclear if it has an effect on wound healing.

Sore throat

A single dose of dexamethasone or another steroid speeds improvement of a sore throat.

Contraindications

s of dexamethasone include, but are not limited to:
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.

Common

Sudden withdrawal after long-term treatment with corticosteroids can lead to:
Known drug interactions include:
As a glucocorticoid, dexamethasone is an agonist of the glucocorticoid receptor. It has minimal mineralocorticoid activity.

Chemistry

Dexamethasone is a synthetic pregnane corticosteroid and derivative of cortisol and is also known as 1-dehydro-9α-fluoro-16α-methylhydrocortisone or as 9α-fluoro-11β,17α,21-trihydroxy-16α-methylpregna-1,4-diene-3,20-dione. The molecular and crystal structure of dexamethasone has been determined by X-ray crystallography.

Synthesis

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.

History

Dexamethasone was first synthesized by Philip Showalter Hench in 1957. It was introduced for medical use in 1958.
On 16 June 2020, the RECOVERY Trial announced preliminary results stating that dexamethasone improves survival rates of hospitalized patients with COVID-19 receiving oxygen or on a ventilator. Benefits were only observed in patients requiring respiratory support; those who did not require breathing support saw a worse survival rate than the control group, although the difference may have been due to chance.
A preprint containing the full dataset was published on 22 June 2020 and demand for dexamethasone surged after publication of the preprint. The preliminary report was published in The New England Journal of Medicine on 18 July 2020.
The World Health Organization states that dexamethasone should be reserved for seriously ill and critical patients receiving COVID-19 treatment in a hospital setting, and the WHO Director-General stated that "WHO emphasizes that dexamethasone should only be used for patients with severe or critical disease, under close clinical supervision. There is no evidence this drug works for patients with mild disease or as a preventative measure, and it could cause harm." In July 2020, the WHO stated they are in the process of updating treatment guidelines to include dexamethasone or other steroids.
In July 2020, the European Medicines Agency started reviewing results from the RECOVERY study arm that involved the use of dexamethasone in the treatment of patients with COVID-19 admitted to the hospital to provide an opinion on the results and in particular the potential use of dexamethasone for the treatment of adults with COVID-19.

Society and culture

Price

Dexamethasone is inexpensive. In the United States a month of medication is typically priced less than. In India, a course of treatment for preterm labor is about. The drug is available in most areas of the world.

Route

It may be taken by mouth, as a tablet or elixir, as an injection into a muscle, intravenously, or via an eye drop.

Nonmedical use

Dexamethasone is given in legal Bangladesh brothels to prostitutes not yet of legal age, causing weight gain aimed at making them appear older and healthier to customers and police.
Dexamethasone and most glucocorticoids are banned by sporting bodies including the World Anti-Doping Agency.

Veterinary use

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.