(6α, 11β)-11,17,21-trihydroxy-6-methyl-pregna-1,4-diene-3,20 -dione

Elimination：Plasma t ½ is longer than 3.5 h.

Onset：Onset is 6 to 48 h (IM).

Peak：Times to peak effect are 4 to 8 days (IM) and 1 to 2 h (oral).

Duration：Durations are 1.25 to 1.5 days (oral) and 1 to 4 wk (IM).

ERYTHROMYCIN會增加METHLPRECDNISOLONE的藥理和毒性反應。處理：減量(METHYLPREDNISOLONE↓)。

Anticholinesterases
May antagonize anticholinesterase effects in myasthenia gravis.

Barbiturates
May decrease pharmacologic effect of methylprednisolone.

Hydantoins, rifampin
May increase Cl and decrease efficacy of methylprednisolone.

Ketoconazole
May decrease Cl of methylprednisolone.

Macrolide antibiotics
Significantly decreases methylprednisolone Cl; may need to decrease dose.

Salicylates
May reduce serum levels and efficacy of salicylates.