1.本藥為合成長效型類固醇，作用廣泛，其可能之作用與所有內源性之腎上腺皮質酮（身體自行分泌的類固醇，如可體松-cortisol）相同。

2. 婦女用藥安全等級:D-在妊娠第一期使用。

成人初劑量每次1顆，每天一次，以後可是病情酌增劑量至每次2顆。小孩初劑量每次半顆，每天一次。

Metabolism
Metabolized in the liver by CYP3A4.

Elimination
The t ½ 1.8 to 3.5 h.

Onset
Rapid (injection).

Duration
Short (injection).

Aminoglutethimide
May decrease dexamethasone-induced adrenal suppression.

Amphotericin B
Cardiac enlargement and CHF have been reported.

Anticholinesterases
May antagonize anticholinesterase effects in myasthenia gravis.

Anticoagulants, oral
May alter anticoagulant dose requirements.

Antidiabetic agents
Dexamethasone may increase blood glucose levels, necessitating antidiabetic agent dosage adjustments.

Aprepitant
Dexamethasone plasma levels may be elevated and the t ½ prolonged, increasing the pharmacologic effects and adverse reactions.

Cholestyramine, epinephrine
Dexamethasone plasma levels may be reduced, decreasing the efficacy.

Cyclosporine
Activity of both cyclosporine and dexamethasone may be increased. In addition, convulsions have been reported.

CYP3A4 substrates (eg, erythromycin, indinavir)
Plasma levels may be reduced by dexamethasone, decreasing efficacy.

Digoxin
Because of possible dexamethasone-induced hypokalemia, the risk of arrhythmias may be increased.

Hepatic enzyme inducers (eg, barbiturates, carbamazepine, phenytoin, rifampin)
Dexamethasone plasma levels may be reduced, decreasing the efficacy. In addition, seizure control with phenytoin may be altered.

Hepatic enzyme inhibitors (eg, azole antifungal agents [eg, ketoconazole], estrogens [including oral contraceptives], macrolide antibiotics [eg, erythromycin])
Dexamethasone plasma levels may be elevated, increasing the pharmacologic effects and adverse reactions. In addition, ketoconazole can inhibit adrenal corticosteroid synthesis, causing adrenal insufficiency during dexamethasone withdrawal.

NSAIDs, salicylates
Risk of GI adverse reactions may be increased. In addition, salicylate levels and efficacy may be reduced.

Potassium-depleting agents (eg, amphotericin B, loop and thiazide diuretics)
Risk of hypokalemia may be increased.

Thalidomide
Use with caution, toxic epidermal necrolysis has been reported with concurrent use of dexamethasone.