Chemistry – A synthetic glucocorticoid, dexamethasone occurs as an odorless, white to practically white, crystalline powder that melts with some decomposition at about 250°C. It is practically insoluble in water and sparingly soluble in alcohol. Dexamethasone sodium phosphate occurs as an odorless or having a slight odor, white to slightly yellow, hygroscopic powder. One gram of is soluble in about 2 ml of water; it is slightly soluble in alcohol. Dexamethasone 21-isonicotinate occurs as a nearly odorless and tasteless, white to slight yellow, crystalline powder.
1.3 mg of dexamethasone sodium phosphate is equivalent to 1 mg of dexamethasone; 4 mg/ml of dexamethasone sodium phosphate injection is approximately equivalent to 3 mg/ml of dexamethasone.
Storage/Stability/Compatibility – Dexamethasone is heat labile and should be stored at room temperature (15-30°C) unless otherwise directed by the manufacturer. Dexamethasone sodium phosphate injection should be protected from light. Dexamethasone tablets should be stored in well-closed containers.
Dexamethasone sodium phosphate for injection is reportedly compatible with the following drugs: amikacin sulfate, aminophylline, bleomycin sulfate, cimetidine HCl, glycopyrrolate, lidocaine HCl, nafcillin sodium, netilmicin sulfate, prochlorperazine edisylate and verapamil.
It is reportedly incompatible with: daunorubicin HCl, doxorubicin HCl, metaraminol bitartrate, and vancomycin. Compatibility is dependent upon factors such as pH, concentration, temperature and diluents used. It is suggested to consult specialized references for more specific information (e.g., Handbook on Injectable Drugs by Trissel; see bibliography).
Contraindications/Precautions – Because dexamethasone has negligible mineralocorticoid effect, it should generally not be used alone in the treatment of adrenal insufficiency. For more information refer to the Glucocorticoid monograph.
a) For treatment of heatstroke: 1mg/5 kg body weight (Schmidt, 1986).
Dexamethasone Chewable Tablets; Pet-Derm III ® (Pfizer) (Rx). 0.25 mg scored tablets. Approved for dogs only.
Dexamethasone Injection 2 mg/ml; Azium® Solution (Schering),Dexameth-a-Vet® (Anthony) (Rx) generic; (Rx) Approved for use in dogs, cats, horses and cattle. There are no withdrawal times required when used in cattle.
Dexamethasone Sodium Phosphate Injection 4 mg/ml (equivalent to 3 mg/ml dexamethasone); Azium® SP Injection (Schering), Dex-A-Vet Injection (Anthony), generic; (Rx) Approved for use in horses.
Human-Approved Products: All require a presecription (Rx); many different trade named products are available.