What is the mechanism of action of dexamethasone?

 DEXAMETHASONE 

It is a glucocorticoid with potent anti-inflammatory properties.It is also known as Decadron, Maxidex, Dexamethazone,Dexasone,Hexadrol,Oradexon,Desametasone,Millicorten,Auxiron,Calonat,Dexacort,Dexasone,Azium,Decasone,Dectancyl,Dekacort,Dergramin,Mymethasone,Decaderm. Dexamethasone is an odorless white to off white crystalline powder with a bitter taste. It is solluble in water. When heated to decomposition it emit toxic fumes of hydrogen fluoride. The moleculer weight of Dexamethasone is 392.5gm/mol. The melting point is 504 to 507⁰F (NTP,1992).

Structure -

The moleculer formula of Dexamethasone is,

                                   [C22H29FO5]

The IUPAC name of Dexamethasone is,

9-fluoro-11,17-dihydroxy-17-(2-hydroxyacetyl) -10,13,16-trimethyl-6,7,8,11,12,14,15,16-octahydrocyclopentaphenanthren-3-one.

Mechanism of action-

Glucocorticoids are both natural and synthetic. Natural glucocorticoids(cortisone) are posseses sodium-retaining characteristics. They are absorbed from the gastrointestinal tract. The different metabolic effects are shown because of glucocorticoids, they modify the body immune response. Dexamethasone is a synthetic analog of glucocorticoid agent, are primarily used for their anti-inflammatory effects. At equipotent anti-inflammatory doses,dexamethasone almost completely lack the sodium retaining property of hydrocortisone.

                           Glucocorticoids are attached with G-protien coupled receptor, glucocorticoid receptor, mineralocorticoid receptor, which carry the drug to its target sight. 

Effects of Dexamethasone are approximately 30 times more potent than Cortisone. 

Dosage-

The initial dose for airway edema is ,0.5 to 2mg per killo per day orally or intramuscular or intravenous in four devided doses given one day prior to extabutation and continued for one day later.

The initial dose for inflammation is, 0.008 to 0.3mg per kg per day in 2-4 divided doses.

The initial dose for meningitis is,0.6mg per kg  per day intravenously in four divided doses for 2-4 day 10 to 20 minutes prior.

Uses-

It is used in the treatment of, 

• Inflammation. 
• Arthritis. 
• Allergies. 
• Asthma. 
• Blood,kidney,eye thyroid and initial disorder. 

Side-effects-

The major Side-effects of Dexamethasone are,

• Stomach upset. 
• Stomach irritation. 
• Vomiting.
• Nausea. 
• Headache. 
• Dizziness. 
• Insomnia.
• Depression. 
• Restlessness. 

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