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Dexamethasone

Overview

Chemically Dexamethasone is 9-Fluoro-11ß, 17, 21-trihydroxy-16a-methylpregna-1, 4-diene-3, -20-dione. Dexamethasone is a corticosteroid. It reduces swelling and inflammation. Dexamethasone is used in different conditions such as skin diseases, allergic conditions, breathing problems, cancer, blood disorders, eye diseases and in arthritis. Dexamethasone is also used to treat nausea and vomitting produced by cancer chemotherapy;.

Category:

Primary Characterstics

Molecular Structure of Dexamethasone
Dexamethasone Sodium Phospate is the derivative of Dexamethasone. It is of Synthetic origin and belongs to Steroid. It belongs to Glucocorticoid agonist pharmacological group on the basis of mechanism of action and also classified in Corticosteroid Nasal pharmacological group.The Molecular Weight of Dexamethasone is 392.50.
It is weakly alkaline drug, 6.75% solution of the drug is isotonic.

Pharmacokinetics

Oral absorption of Dexamethasone is found to be 90% . Volume of distribution is found to be 0.58 l/kg and plasma protien binding is 66-77%. and metabolism is reported slow via liver. Renal Excretion accounts for 60% and plasma half life is 3.6 ± 0.9 hr.

Indications

Contraindications

Drug Interactions

Dexamethasone is known to interact with other drugs, the details of drug interactions is as follows:

DrugDetailsSeverityOnsetManagement
Albendazole
AminoglutethimideAminoglutethimide accelerates the metabolism of Dexamethasone (reduced effects).
AprepitantIncreased the AUC of dexamethasone, a CYP3A4 substrate, by 2.2-fold on Days 1 and 5 of chemotherpy when given in regimen. The oral dexamethasone doses should be reduced by approximately 50% when coadministered with aprepitant capsules)(125 mg/80 mg regimen), to achieve exposures of dexamethasone similar to those obtained when it is given without aprepitant capsules. A single dose of aprepitant capsules (40 mg) when coadministered with a single oral dose of dexamethasone 20 mg, increased the AUC of dexamethasone by 1.45-fold. Therefore, no dose adjustment is recommended.
Carbamazepinecarbamazepine increase clearance of cortisteroids.
DiazoxideHypotensive effect of Diazoxide antagonised by Dexamethasone.
Dolasetron (Mesylate)
Ephedrine
EphedrineEphedrine increase urinary excretion of Dexamethasone
Fosphenytoin
Granisetron (HCl)
Indinavir (Sulphate)
NatamycinConcurrent use may increase the toxicity, therefore concomitant use is contraindicated.
NateglinideConcurrent use may reduce the hypoglycemic action of Nateglinide.
OxandroloneThe concomitant administration of oxandrolone and adrenal cortical steroids may increase the edema in patients with edema. The mechanism and clinical significance are unknown. Closer monitoring may be appropriate, especially in patients with conditions that may be aggravated by fluid retention.Minor
PerindoprilTheoretical potential for DEXAMETHASONE [ORAL] reducing the HYPOTENSIVE effect of Perindopril Erbumine. Moderate
Phenobarbitonephenobarbitone decrease plasma half life and bioavailibility of dexamethasone by 50%
Phenytoin (Na)
Phenytoin (Na)
RhubarbPotassium deficiency can be increased by concurrent use.
Rifampicin
Ritonavir
Saquinavir
SunitinibMay decrease sunitinib concentrations.
Technetium Tc-99m GluceptateUptake of technetium Tc 99m gluceptate in cerebral tumor or abscess may be decreased because of reduced peritumor edema caused by the Dexamethasone.
Technetium Tc-99m OxidronateLong-term therapy with glucocorticoids may induce bone mineral depletion, thus causing decreased bone uptake of technetium Tc 99m oxidronate.

These interactions are sometimes beneficial and sometimes may pose threats to life. Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.

Interference in Pathology

  • Measurement of Serum Digoxin by Immunoassay.
  • Impairment of Glucose Tolerance
  • Lowers basal TSH, FSH and LH Levels
  • Reduced levels of Prolactin
  • Reuces hGH response to various stimuli
  • Lowering of Plasma cortisol,Potassium, and Oestrogens

Side Effects

The severe or irreversible adverse effects of Dexamethasone, which give rise to further complications include Glaucoma, Peptic ulceration, Myopathy, Osteoporosis, Growth retardation, Aseptic bone necrosis, Ocular hypertension, Subcapsular cataract, Pancreatic disturbance, Cushing like features, Oedema, Retinal detachment, Moon face, Truncal obesity.

Dexamethasone produces potentially life-threatening effects which include Collapse, Suppression of hypothalamus-pituitary-adrenal axis. which are responsible for the discontinuation of Dexamethasone therapy.

The symptomatic adverse reactions produced by Dexamethasone are more or less tolerable and if they become severe, they can be treated symptomatically, these include Nausea, Vomiting, Insomnia, Nervousness, Nocturia, Increased appetite, Obesity, Facial rounding, Fragility of skin, Euphoria, Glucose intolerance, nervousness, adrenal suppression, protein catabolism, lipid metabolism.

Available Brands

Click on the appropriate strength of the dosage form to view its available brands.

Single Ingredient

Inj: 4 mg, 20 mg, 2 mg/ml, 4 mg/ml,
Drops: 1 mg,
Eye Drops: 0.1 %w/v, 0.1 %w/w,
Oint: 0.1 %w/w,
Tabs: 0.5 mg,

Multi ingredient

Drops: 1 mg, 0.1 %, 0.1 %w/v,
Eye Drops: 0.1 %w/v, 0.2 %w/v,
Ear Drops: 0.1 %w/v,
Eye Oint: 0.1 %w/w,
E and E Drops: 0.1 %w/v,
Oint: 0.1 gm,
Cream: 1 mg, 4 mg, 0.1 gm, 0.1 %w/w, 0.4 %w/w, 0.04 %w/w, 3500 IU/g,

Dosage

Dexamethasone's dosage details are as follows:
Dose Single Dose Frequency Route Instructions

Adult Dosage

0.5 to 24 mg12 (12.25)As recommended.IV,IMOnce in Weeks
0.1 %0.1 (0.1)As recommended.OphthalmicAs Required.To be given as drops.
0.5 to 10 mg5.2 (5.25)24 hourlyPO

Paedriatic Dosage ( 20 Kg. )

0.05 mg/kg0.05 (0.05)6 hourlyIntra Venous-
1 %1 (1)As recommended.OpthalmicAs Required
0.05 mg/kg0.05 (0.05)6 hourlyOral-

Neonatal Dosage ( 3 Kg. )

0.2 mg/kg0.2 (0.2)8 hourlyIntramuscular
0.2 mg/kg0.2 (0.2)8 hourlyIntravenous
0.2 mg/kg0.2 (0.2)8 hourlyoral

High Risk Groups

Drug should not be given to Paediatrics, Pregnant Mothers, Geriatrics, and Neonates.

If prescribing authority justifies the benefits of the drug against the possible damages he/she should reevaluate them and consult the reference material and previous studies.

Warning / Precautions

Dexamethasone should be used with caution in patients with active tuberculosis infection of respiratory tract or in untreated fungal, bacterial or systemic viral infections. Corticosteroids should only be used systemically with great caution in the presence of congestive heart failure (CHF), recent myocardial infraction (MI), hypertension, diabetes mellitus, epilepsy, glaucoma, hypothyroidism, liver failure, osteoprosis, peptic ulceration or renal impairment. Children may be at increase risk of some adverse effects, corticosteroid cause growth retardation and prolonged use is rarely justified. Passive immunization is recommended to non-immune patients who do come in contact with chickenpox or measles. Live vaccine should not be given to patients receiving high dose systemic corticosteroid therapy nor for atleast 3 months afterwards, killed vaccine or toxoids may be given, although the response may be attenuated. During prolong treatment with corticosteroids, patients should be examined regularly, sodium intake may need to be reduced and calcium and potassium supplement may be necessary. Patient should carry cards given full details of their corticosteroid therapy. Avoid use during pregnancy. Use nasal steroids with caution until healing has occurred. Dose adjustment required in patient with renal

Storage Conditions

Inj, Cream, Gel, Ear Soln, Eye Oint, Soln or Susp

Store Below 40°C. Do not Freeze. Protect from Sunlight.

Oral Inhaler, Nasal Aerosol

Store at room temperature, Below 40°C. Do not Freeze.

Tab, Oral Elixir, Oral Soln

Store in a well closed container, Below 40°C.

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