dexamethasone (systemic)
Decadron, Deronil ◆, Dexameth, Dexasone ◆, Dexone, Hexadrol

dexamethasone acetate
Cortastat L.A., Dalalone D.P., Dalalone L.A., Decadron-LA, Decaject-L.A., Dexasone L.A., Dexone L.A., Solurex LA

dexamethasone sodium phosphate
AK-Dex, Cortastat, Dalalone, Decadrol, Decadron, Decadron Phosphate, Decaject, Dexameth, Dexasone, Dexone, Hexadrol Phosphate, Oradexon ◆, Solurex

Available forms
Available by prescription only
dexamethasone
Elixir: 0.5 mg/5 ml
Oral solution: 0.5 mg/0.5 ml, 0.5 mg/5 ml
Tablets: 0.25 mg, 0.5 mg, 0.75 mg, 1 mg, 1.5 mg, 2 mg, 4 mg, 6 mg
dexamethasone acetate
Injection: 8 mg/ml, 16 mg/ml suspension
dexamethasone sodium phosphate
Injection: 4 mg/ml, 10 mg/ml, 20 mg/ml
Injection (I.V. use only): 24 mg/ml

Indications and dosages
 Cerebral edema. dexamethasone sodium phosphate Adults: Initially, 10 mg I.V.; then 4 mg I.M. q 6 hours for 2 to 4 days. Then taper over 5 to 7 days.
 Inflammatory conditions, allergic reactions, neoplasias. dexamethasone (systemic) Adults: 0.75 to 9 mg P.O. daily divided b.i.d., t.i.d., or q.i.d.
Children: 0.024 to 0.34 mg/kg P.O. daily in four divided doses.
dexamethasone acetate
Adults: 4 to 16 mg intra-articularly or into soft tissue q 1 to 3 weeks. Or, 0.8 to 1.6 mg into lesions q 1 to 3 weeks. Or, 8 to 16 mg I.M. q 1 to 3 weeks, p.r.n.
dexamethasone sodium phosphate
Adults: 0.2 to 6 mg intra-articularly, intralesionally, or into soft tissue. Or, 0.5 to 9 mg I.M.
 Shock (other than adrenal crisis). dexamethasone sodium phosphate Adults: 1 to 6 mg/kg I.V. daily as a single dose; or 40 mg I.V. q 2 to 6 hours, p.r.n.
 Adrenal insuffiency. Adults: 0.5 mg P.O. q 6 hours for 48 hours.
 Adrenal insufficiency. dexamethasone (systemic) Children: 0.024 to 0.34 mg/kg P.O. daily in four divided doses.
dexamethasone sodium phosphate Adults: 0.5 to 9 mg I.M. or I.V. daily.
Children: 0.235 to 1.25 mg/m² I.M. or I.V. once daily or b.i.d.
 Tuberculous meningitis. Adults: 8 to 12 mg daily tapered over 6 to 8 weeks.
 Prevention of hyaline membrane disease in premature infants ◇. Adults: 5 mg (phosphate) I.M. t.i.d. to mother for 2 days before delivery.
 Prevention of chemotherapy-induced nausea and vomiting ◇. Adults: 10 to 20 mg. I.V. before chemotherapy. Additional doses (individualized and usually lower than initial dose) may be given I.V. or P.O. for 24 to 72 hours after chemotherapy, if needed.

Pharmacodynamics
Anti-inflammatory and immunosuppressant action: Dexamethasone stimulates the synthesis of enzymes needed to decrease the inflammatory response. It causes suppression of the immune system by reducing activity and volume of the lymphatic system, producing lymphocytopenia (primarily T-lymphocytes), decreasing passage of immune complexes through basement membranes, and possibly by depressing reactivity of tissue to antigen-antibody interactions.
 Drug is a long-acting synthetic adrenocorticoid with strong anti-inflammatory activity and minimal mineralocorticoid properties. It’s 25 to 30 times more potent than an equal weight of hydrocortisone.
 The acetate salt is a suspension and shouldn’t be used I.V. It’s particularly useful as an anti-inflammatory agent in intra-articular, intradermal, and intralesional injections.
 The sodium phosphate salt is highly soluble and has a more rapid onset and a shorter duration of action than does the acetate salt. It’s most commonly used for cerebral edema and unresponsive shock. It can also be used in intra-articular, intralesional, or soft-tissue inflammation. Dexamethasone is also used as a treatment for chemotherapy-induced nausea and bronchial asthma symptoms and as a diagnostic test for Cushing’s syndrome.

Pharmacokinetics
Absorption: After oral use, drug is absorbed readily. The suspension for injection has a variable onset and duration of action, depending on whether it’s injected into an intra-articular space, a muscle, or the blood supply to the muscle. After I.V. injection, dexamethasone is rapidly and completely absorbed into the tissues.
Distribution: Removed rapidly from blood and distributed to muscle, liver, skin, intestines, and kidneys. Dexamethasone is bound weakly to plasma proteins (transcortin and albumin). Only the unbound portion is active. Adrenocorticoids appear in breast milk and the placenta.
Metabolism: Metabolized in the liver to inactive glucuronide and sulfate metabolites.
Excretion: Inactive metabolites and small amounts of unmetabolized drug are excreted by the kidneys. Insignificant quantities are also excreted in feces; biologic half-life is 36 to 54 hours.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug or its components and in those with systemic fungal infections.
  Use cautiously in patients with recent MI, GI ulcer, renal disease, hypertension, osteoporosis, diabetes mellitus, hypothyroidism, cirrhosis, diverticulitis, nonspecific ulcerative colitis, recent intestinal anastomoses, thromboembolic disorders, seizures, myasthenia gravis, heart failure, tuberculosis, ocular herpes simplex, emotional instability, and psychotic tendencies. Because some formulations contain sulfite preservatives, also use cautiously in patients sensitive to sulfites.

Interactions
Drug-drug. Aminoglutethimide: May cause loss of dexamethasone-induced adrenal suppression. Monitor patient for effect.
Amphotericin B, diuretics: Increases risk of hypokalemia. Monitor serum potassium levels.
Antacids, cholestyramine, colestipol: Decreases corticosteroid effect. Monitor patient closely, and adjust dosage as needed.
Aspirin, NSAIDs: May increase risk of GI ulceration. Use together cautiously.
Barbiturates, phenytoin, rifampin: May cause decreased corticosteroid effects. Adjust dosage as needed.
Cardiac glycosides: Hypokalemia may increase risk of toxicity. Adjust dosage as needed.
Ephedrine: May cause decreased half-life and increased clearance of dexamethasone. Monitor patient for effect.
Estrogens, oral contraceptives: May reduce dexamethasone metabolism by increasing transcortin levels. Monitor patient carefully.
Insulin, oral antidiabetics: Increases risk of hyperglycemia. Adjust dosage as needed.
Isoniazid, salicylates: Increases metabolism of these drugs. Monitor patient carefully.
Ketoconazole: May increase area under the curve and decrease clearance of dexamethasone. Monitor patient for increased adverse effects.
Oral anticoagulants: Decreases anticoagulant effects. Monitor PT and INR closely.
Potassium-depleting diuretics: May cause hypokalemia. Monitor serum potassium level.
Skin-test antigens: Decreases response. Defer skin testing until therapy is completed.
Toxoids, vaccines: Decreases antibody response and increases risk of neurologic complications. Avoid use together.
Drug-lifestyle. Alcohol use: Increases risk of gastric irritation and GI ulceration. Discourage alcohol use.

Adverse reactions
CNS: euphoria, insomnia, psychotic behavior, pseudotumor cerebri, vertigo, headache, paresthesia, seizures.
CV: heart failure, hypertension, edema, arrhythmias, thrombophlebitis, thromboembolism.
EENT: cataracts, glaucoma.
GI: peptic ulceration, GI irritation, increased appetite, pancreatitis, nausea, vomiting.
GU: menstrual irregularities.
Metabolic: hypokalemia, hypocalcemia, hyperglycemia, carbohydrate intolerance, increased urine glucose and calcium levels.
Musculoskeletal: muscle weakness, osteoporosis, growth suppression in children.
Skin: hirsutism, delayed wound healing, acne, skin eruptions, atrophy at I.M. injection sites.
Other: susceptibility to infections, acute adrenal insufficiency following increased stress (infection, surgery, or trauma) or abrupt withdrawal after long-term therapy, cushingoid state (moonface, buffalo hump, central obesity), growth suppression in children, increased sweating, hirsutism.

Effects on lab test results
• May increase glucose and cholesterol levels. May decrease potassium, calcium, T₃, and T₄ levels.

Overdose and treatment
Acute ingestion, even in massive doses, rarely poses a clinical problem. Toxic signs and symptoms rarely occur if drug is used for less than 3 weeks, even at large dosage ranges. However, long-term use causes adverse physiologic effects, including suppression of the hypothalamic-pituitary-adrenal axis, cushingoid appearance, muscle weakness, and osteoporosis.
 In large, acute overdose, treatment includes gastric lavage or emesis and the usual supportive measures.

Special considerations
 ALERT After abrupt withdrawal, patient may experience rebound inflammation, fatigue, weakness, arthralgia, fever, dizziness, lethargy, depression, fainting, orthostatic hypotension, dyspnea, anorexia, or hypoglycemia. After prolonged use, sudden withdrawal may be fatal. Dose must be gradually tapered.
• Determine whether patient is sensitive to other corticosteroids.
• For better results and less toxicity, consider a once-daily dose in the morning.
• Most adverse reactions to corticosteroids are dose- or duration-dependent.
• Give drug by I.M. injection deep into gluteal muscle. Rotate sites. Avoid S.C. injection.
• Drug is being used investigationally to prevent hyaline membrane disease (respiratory distress syndrome) in premature infants. The suspension (phosphate salt) is given I.M. to the mother two or three times daily for 2 days before delivery.
• Dexamethasone causes false-negative results in the nitroblue tetrazolium test for systemic bacterial infections and decreases ¹³¹I uptake and protein-bound iodine levels in thyroid function tests.
• Dexamethasone, when used for cerebral edema, may cause a decrease in uptake of radioactive material, altering the results of the brain scan.
Pediatric patients
• Long-term use of drug in children and adolescents may delay growth and maturation.

Patient education
• Tell patient not to stop drug abruptly or without medical approval.
• Instruct patient to take drug with food or milk.
• Teach patient signs of early adrenal insufficiency: fatigue, muscle weakness, joint pain, fever, anorexia, nausea, dyspnea, dizziness, and fainting.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use