Description
Fluprednisolone (6α-fluoro-11β,17,21-trihydroxy-pregna-1,4-diene-3,20-dione) is the 16-desmethyl analogue of
paramethasone. Its activity is similar to that of paramethasone, and it has approximately 2.5 times the
antirheumatic potency of prednisolone. With doses of 2 to 7 mg, evidence of salt and water retention has not
been noted. The therapeutic index, however, probably is the same or only a little greater than that for
prednisolone. Because no new adverse reactions have been noted during the administration of this drug on a
short-term basis, it seems that a 6α-fluoro group does not deleteriously affect the activity of prednisolone
(49,75).
Manufacturing Process
5α,11β,17α-Trihydroxy-6β-Fluoro-21-Acetoxyallopregnane-3,20-Dione:A solution of 0.47 gram of 5α,11β,17α-trihydroxy-6β-fluoro-21acetoxyallopregnane-3,20-dione-3-ethylene ketal in 35 ml of acetone and 4 ml of 1 N sulfuric acid solution was gently boiled on the steam bath for 10 minutes, cooled and neutralized with dilute sodium bicarbonate solution. Addition of water and cooling gave 0.33 gram of 5α,11β,17α-trihydroxy-6βfluoro-21-acetoxyallopregnane-3,20-dione, MP 230° to 240°C.
6β-Fluoro-11β,17α-Dihydroxy-21-Acetoxy-4-Pregnene-3,20-Dione(6βFluorohydrocortisone Acetate): A solution of 100 mg of 5α,11β,17α-trihydroxy6β-fluoro-21-acetoxyallopregnane-3,20-dione in 4.9 ml of acetic acid and 0.1 ml of water was refluxed for a period of 1 hour, cooled, diluted with 50 ml of water and evaporated to dryness under reduced pressure. The residue was chromatographed over Florisil (synthetic magnesium silicate) to give one fraction (77 mg) eluted with methylene chloride plus 10% acetone. Crystallization from acetone-Skellysolve B-hexanes gave 38 mg of 6β-fluoro11β,17α-dihydroxy-21-acetoxy-4pregnene-3,20-dione (6β-fluorohydrocortisone6β-Fluoro-11β,17α-Dihydroxy-21-Acetoxy-1,4-Pregnadiene-3,20-Dione: A medium consisting of 1% dextrose hydrate, 2% cornsteep liquor of 60% solids and Kalamazoo tap water was adjusted to pH 4.9 with sodium hydroxide. The medium was steam sterilized at 15 pounds pressure for 30 minutes, cooled, and then inoculated with a 24-hour growth, from spores, of Septomyxa affinis, ATCC 6737. The medium was agitated, sparged with sterile air at the rate of one-tenth volume of air per volume of medium per minute. At the end of 24 hours of fermentation at room temperature, the pH was about 7.4.
To this culture there was added a solution of 6β-fluoro-11β,17α-dihydroxy-21acetoxy-4-pregnene-3,20-dione (6β-fluorohydrocortisone acetate), dissolved in diethylformamide. The solution was prepared by dissolving five parts of the steroid in 100 parts of the solid and adding about 10 cm of the solution per liter of the medium. Fermentation was continued for a period of 48 hours whereupon the mycelium and beer were extracted thoroughly with methylene chloride. The extract was washed with sodium bicarbonate solution and then with water, dried and concentrated in vacuo to a slightly viscous residue. The residue, after reacetylation with acetic anhydride in pyridine, was fractionated chromatographically and 6β-fluoro-11β,17α-dihydroxy-21-acetoxy-1,4pregnadiene-3,20-dione was recovered as a light-colored crystalline solid. Isomerization to the 6β-fluoro product is effected by streaming dry HCl into a cold chloroform/ethanol solution of the 6α-epimer.
