9-fluoro-11,17-dihydroxy-17- (2-hydroxyacetyl)- 10,13-dimethyl- 1,2,6,7,8,9,10,11,12, 13,14,15,16,17- tetradecahydrocyclopenta[a]phenanthren-3-one

Absorption
Fludrocortisone is rapidly absorbed from the GI tract. T max is 1.7 h.

Elimination
The plasma t 1/ 2 is about 3.5 h. The biological t 1/ 2 is 18 to 36 h.

Amphotericin, potassium-losing diuretics
May increase potassium loss.

Anticholinesterase agents (eg, neostigmine)
May antagonize the effects of anticholinesterase agents in myasthenia gravis.

Anticoagulants (eg, warfarin)
Dose requirement of anticoagulant may be reduced or effect opposed.

Barbiturates, hydantoins (eg, phenytoin), rifampin
Decreased fludrocortisone activity.

Salicylates
Serum levels may be reduced by corticosteroids, decreasing the effectiveness; in addition, the ulcerogenic effects of both agents may be increased.