Dexamethasone Pharmacology


About Dexamethasone
A potent synthetic glucocorticoid, Antiasthmatic, anti-inflammatory and immunosuppressant.
Mechanism of Action of Dexamethasone
The drug exerts it`s pharmacological action by penetrating and binding to cytoplasmic receptor protein and causes a structural change in steroid receptor complex. This structural change allows it`s migration in to the nucleus and then binding to specific sites on the DNA which leads to transcription of specific m-RNA and which ultimately regulates protein synthesis. It exerts highly selective glucocorticoid action. It stimulates the enzymes needed to decrease the inflammatory response.
The drug exerts anti-inflammatory and immunosuppressant actions as follows: - 1) Induce lipocortins in macrophages, endothelium, and fibroblasts which inhibits phospholipase A2 and thus decreases the production of Prostaglandins, leukotriens (LT), and platelet activating factor, 2) Causes negative regulation of genes for cytokines in macrophages, endothelial cells and lymphocytes and thus decreases the production of interleukins (IL-1, IL-2, IL-3, IL-6), TNF-a, GM-CSF (granulocyte macrophage colony stimulating factor), Gama interferon and suppresses fibroblast proliferation and T-lymphocyte functions and interferes chemo taxis. 3) Decreases the production of acute phase reactants from macrophages and endothelial cells and interferes complement function. 4) Decreases the production of ELAM-1(Endothelial leukocyte adhesion molecule-1) and ICAM-1(intracellular adhesion molecule-1) in endothelial cells. 5) Inhibit IgE mediated histamine and LT-C4 release from basophiles and the effects of antigen-antibody reaction is not mediated 6) Reduces the production of collagenase and stromolysin and thus prevents tissue destruction.
Dexamethasone has antiemetic properties, particularly against acute and delayed vomiting induced by cancer chemotherapy. It may be used alone for prevention of acute symptoms associated with moderately-emetogenic treatment and is combined with a 5-HT3 antagonist for highly-emetogenic treatment. Dexamethasone is also effective for the prevention of postoperative nausea and vomiting, and may be used to manage nausea and vomiting in palliative care.
Pharmacokinets of Dexamethasone
Absorption: Well absorbed orally, Distribution: Distributed in to muscle, liver, kidney, skin, and intestine. It crosses the placenta and also secreted in breast milk, Metabolism: Metabolized in liver in to inactive metabolites by glucuronide and sulfate conjugation. Excretion: Metabolites are excreted mainly through urine and a small amount is excreted through faeces.
Onset of Action for Dexamethasone
1 to 2hours
Duration of Action for Dexamethasone
2 or more days
Half Life of Dexamethasone
36 to 54 hours
Side Effects of Dexamethasone
1.Susceptibility to infection
2.Peptic ulcer
7.Atrophy of adrenal cortex(on prolonged therapy)
8.Suppression of adrenocorticotropic hormone
9.Cushing`s syndrome
10.Inhibition of growth in children
12.Behavioral disturbances
13.Thromoembolic disorders
17.Muscle wasting
18.Gastrointestinal discomfort
19.Increased appetite
20.Delayed wound healing
25.Heart failure
27.Posterior sub capsular cataract
30.Increased intracranial pressure
Eye preparation:
3.Stinging in the eye
4.Blurred vision

Contra-indications of Dexamethasone
1.Hypersensitivity to the drug
4.Untreated infections
5.Systemic fungal infections
7.Congestive heart failure
8.Renal impairment
Special Precautions while taking Dexamethasone
1.Avoid sudden discontinuation of the drug
2.Use lower dosages as much as possible
3.Ocular herpes simplex
4.Primary glaucoma
5.Peptic ulcer
7.Recent myocardial infarction
8.Heart failure
9.Diabetes mellitus
15.Myasthenia gravis
16.Hepatic impairment
17.Non specific Ulcerative colitis
19.Recent intestinal anastomosis
20.Thromboembolic disorders
Eye preparation:
2.Contact lens wearer

Pregnancy Related Information
Old Age Related Information
Use with caution.
Breast Feeding Related Information
Use with caution.
Children Related Information
Use with caution.
Neonates: Contraindicated
Indications for Dexamethasone
1.Inflammatory conditions
2.Allergic reactions
5.Intra-articular and soft tissue inflammation
7.Rheumatoid arthritis
8.Adrenal insufficiency
9.Tuberculous meningitis
10.Respiratory diseases
12.Cerebral oedema.
13.Acute gout
14.Nausea and vomiting induced by cancer chemotherapy
15. Pemphigus
Interactions for Dexamethasone
ENDOCRINE SYSTEM: Barbiturates: Decreases efficacy of dexamethasone.
Carbamazepine, Primidone: Decreases efficacy.
Oral contraceptives: Increases efficacy of dexamethasone.
Ephedrine: Decrease efficacy of dexamethasone.
Oestrogens: Decrease efficacy of dexamethasone
Hydantoins: Decrease efficacy of dexamethasone
Ketoconazole: Increase efficacy of dexamethasone
Rifampicin: Decreases efficacy.
Dexamethasone effects the actions of the following:
Anticholinesterases: Efficacy antagonised in myasthenia gravis.
Oral anticoagulants: Altered response.
Cyclosporine: Increased cyclosporine efficacy leading to enhanced toxicity.
Digitalis glycosides: Increased toxicity associated with hypokalaemia.
Isoniazid: Decreased serum levels of isoniazid.
Salicylates: Decreased serum levels of salicylates.
Diuretics: Increase efficacy may cause increased hypokalaemia and increased hyperglycemia.
Non-depolarising muscle relaxants: Altered response.
Theophyllines: Altered response of either agent.
IUCDs: contraceptive failure.
Lab. Tests: a) Increases serum cholesterol levels.
Increases urine glucose levels.
Decreases Thyroid I131 uptake. Decreases T3 serum levels. Decreases serum potassium.
Brain Scan: Dexamethasone alters result of brain scan due to decreased uptake of radioactive material.

Typical Dosage for Dexamethasone
Oral: 0.5 to 10mg/day depending up on the severity of the condition.
I.M. or I.V.: 0.5 to 20mg/day I.M. or as slow I.V. injection depending up on the severity of the condition; repeated as required up to 80mg/day.
Antiemetic: 4 to 8 mg by mouth immediately before moderately-emetogenic chemotherapy and 20 mg by intravenous injection for more severely emetogenic chemotherapy.
Children: 100mcg to 500mcg/kg/day
Schedule of Dexamethasone
Storage Requirements for Dexamethasone
Store at room temperature in a well closed light resistant container. Protect from excess heat and moisture. Keep out of reach of children.
Effects of Missed Dosage of Dexamethasone
Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose. Continue the regular schedule. Do not double the dose.
Effects of Overdose of Dexamethasone
Provide symptomatic treatment and supportive measures.

Home Delivery for Dexamethasone in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including dexamethasone.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for dexamethasone and other medicines and health products. Home delivery services for dexamethasone may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take dexamethasone only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for dexamethasone before they complete the sale. You can get this information while placing the order for dexamethasone with the pharmacy.

Dexamethasone is a generic medicine name and there are several brands available for it. Some of the brands for dexamethasone might be better known than dexamethasone itself. If the pharmacy that's willing to deliver medicines to your home doesn't have dexamethasone in stock, you can ask for one of the branded alternatives for dexamethasone.