Note: For more information refer to the monograph: Glucocorticoids, General Information.
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.
For adjunctive therapy of insect bites or stings:
a) 2 mg/kg IM or IV q4h (use epinephrine if anaphylaxis develops) (Fowler 1993)
For adjunctive therapy of cerebral edema secondary to polioencephalomalacia:
a) 1 - 2 mg/kg intravenously (Dill 1986)
For adjunctive therapy of radial nerve injury, or femoral nerve paralysis:
a) Adult cattle (400-800 kg and not pregnant): 20 - 40 mg IM or IV; Calves: 10 mg IM or IV. Taper or discontinue therapy in 2-3 days. Many cases require only a single dose. (Rebhun 1986)
For adjunctive therapy of obturator nerve paralysis:
a) 10 - 40 mg parenterally once daily for 2-3 days then discontinue. (Rebhun 1986)
For adjunctive therapy of peroneal nerve injuries:
a) 10 - 30 mg parenterally for acute cases when not contraindicated due to pregnancy or infection. (Rebhun 1986)
For elective inducement of parturition or termination of pregnancy:
a) For abortion: 25 mg parenterally with 25 mg prostaglandin F2 after 150 days of gestation. For inducement or parturition from 8th month of gestation on: 20 mg IM. (Drost 1986)
b) For inducement of parturition when given within 2 weeks of normal term: 20 - 30 mg IM (Barth 1986)
For adjunctive therapy of aseptic laminitis:
a) 5 - 20 mg IM or IV; continue therapy for 2-3 days (Berg 1986)
For primary bovine ketosis:
a) 5 - 20 mg IV or IM (Package Insert; Azium®— Schering)
For glucocorticoid therapy:
a) 0.05 - 0.2 mg/kg once daily IV, IM or PO (Robinson 1987)
Dexamethasone suppression test:
a) 20 mg IM. Normal values: Cortisol levels decrease 50% in 2 hours, 70% in 4 hours, and 80% at 6 hours. At 24 hours levels are still depressed about 30% of original value. (Beech 1987b)
For labeled indications (various inflammatory conditions associated with the musculoskeletal system) for dexamethasone 21-isonicotinate (Voren®):
a) 5 - 20 mg IM; may repeat. (Package Insert; Voren®— Bio-ceutic)
For labeled indications (anti-inflammatory/glucocorticoid agent) for dexamethasone injection (Azium®):
a) 2.5 - 5 mg IV or IM. (Package Insert; Azium®— Schering)
For labeled indications (anti-inflammatory/glucocorticoid agent) for dexamethasone sodium phosphate injection (Azium®-SP):
a) 2.5 - 5 mg IV. (Package Insert; Azium®— Schering)
For adjunctive therapy of anaphylaxis:
a) 2 mg/kg IV (Smith 1989)
a) For treatment of heatstroke: 1mg/5 kg body weight (Schmidt, 1986).
1986. Proboscidea (Elephants). In: Fowler,M.E. (Editor), Zoo and
wild animal medicine. W.B. Saunders,
Dosage Forms/Preparations/Approval Status/Withdrawal Times-
Dexamethasone Oral Tablets 0.25 mg; Azium® Tablets (Schering), generic; (Rx) Approved for use in dogs and cats
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.
Tablets: 0.25 mg, 0.5 mg, 0.75 mg, 1 mg, 1.5 mg, 2 mg, 4 mg, & 6 mg
Oral Elixir/Solution: 0.5 mg/5 ml, 0.5 mg/0.5 ml
Dexamethasone Acetate Injection: 8 mg/ml, 16 mg/ml
Dexamethasone Sodium Phosphate Injection: 4 mg/ml, 10 mg/ml, 20 mg/ml, 24 mg/ml
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