Overview
Fluorometholone is the topical synthetic glucocorticoid. Its tropical anti-inflammatory effect is 40 times as much as hydrocortisone, but their effects of oral administration are almost equal. It is mainly used for local treatment of skin allergy, pruritus, rash and other diseases related to allergy. Oral administration is also used for the treatment of breast cancer, childhood leukemia, connective tissue disease, and so on.
Manufacturing Process
The following description is taken from US Patent 2,867,637.
(a) Preparation of 6α-Methyl-9α-Fluoro-11β,17α,21-Trihydroxy-1,4Pregnadiene-3,20-Dione 21-Methanesulfonate: A solution was prepared containing 250 mg of 1-dehydro-6α-methyl-9α-fluorohydrocortisone [G.B. Spero et al, J. Am. Chem. Soc.79, 1515 (1957)] in 6 ml of pyridine. This solution was cooled to 0°C and treated with 0.25 ml of methanesulfonyl chloride. Thereafter the solution was allowed to stir at a temperature between 0° and 5°C for a period of 18 hours. Thereafter ice and 2 ml of water were added, followed by 30 ml of sufficient dilute (5%) hydrochloric acid to neutralize the pyridine. The mixture was then filtered, the precipitate washed with water and dried to give 197 mg of crude 6α-methyl-9α-fluoro11β,17α,21-trihydroxy-1,4-pregnadiene-3,20-dione 21-methanesulfonate of MP 165° to 185°C.
(b) Preparation of 6α-Methyl-9α-Fluoro-11β,17α-Dihydroxy-21-Iodo-1,4Pregnadiene-3,20-Dione: The crude 197 mg of methanesulfonate of 6αmethyl-9α-fluoro-11β,17α,21-trihydroxy-1,4-pregnadiene-3,20-dione was dissolved in 5 ml of acetone and treated with a solution of 197 mg of sodium iodide in 5 ml of acetone. The mixture was heated under reflux with stirring for a period of 15 minutes. The heating was then discontinued and the mixture concentrated to dryness at reduced pressure to give 6α-methyl-9αfluoro-11β,17α-dihydroxy-21-iodo-1,4-pregnadiene-3,20-dione.
(c) Preparation of 6α-Methyl-9α-Fluoro-11β,17α-Dihydroxy-1,4-Pregnadiene3,20-Dione: The crude 6α-methyl-9α-fluoro-11β,17α-dihydroxy-21-iodo-1,4pregnadiene-3,20-dione was slurried with 5 ml of acetic acid and stirred for a period of 45 minutes. Thereafter was added a solution of 250 mg of sodium thiosulfate pentahydrate in 5 ml of water causing the iodine color to disappear. Additional water was added (30 ml) and the reaction mixture was filtered. The resulting solid precipitate was washed with water and dried to give 146 mg of crude 6α-methyl-9α-fluoro-11β,17α-dihydroxy-1,4pregnadiene-3,20-dione.
The crude material was then chromatographed by dissolving 120 mg of 6αmethyl-9α-fluoro-11β,17α-dihydroxy-1,4-pregnadiene-3,20-dione in 300 ml of methylene chloride and allowing the thus obtained solution to be absorbed by a chromatographic column containing 10 grams of Florisil anhydrous magnesium silicate. The column was developed taking fractions of 20 ml each as follows:Fractions 11 through 24 inclusive were combined, evaporated and twice recrystallized from acetone to give pure 6α-methyl-9α-fluoro-11β,17αdihydroxy-1,4-pregnadiene-3,20-dione of melting point 292° to 303°C.
General Description
Fluorometholone, 9-fluoro-11β,17-dihydroxy-6α-methylpregn-4-ene-3,20-dione(Fluor-Op, FML), lacks the typical C21 OH group of GCsand is used exclusively in ophthalmic products. The 17-acetateof fluorometholone is also used as an ophthalmic suspension(Flarex).
