Characterization of related impurities in megestrol acetate.

Three new compounds, 17alpha-acetoxy-2,6-dimethylpregna-1,4,6-triene-3,20-dione (1), 17alpha-acetoxy-2alpha,6-dimethylpregna-4,6-diene-3,20-dione (2), 17alpha-acetoxy-6alpha-methoxylmethylpregna-4-ene-3,20-dione (3), together with five known ones, 17alpha-acetoxy-6beta-hydroxyl-6alpha-methylpregna-4-ene-3,20-dione (4), 17alpha-acetoxy-6alpha-hydroxyl-6beta-methylpregna-4-ene-3,20-dione (5), 17alpha-acetoxy-pregna-4-ene-3,6,20-trione (6), 17alpha-acetoxy-pregna-4-ene-3,20-dione (7) and 17alpha-acetoxy-6-methylene-pregna-4-ene-3,20-dione (8), were isolated and identified from the residual mother liquor of megestrol acetate. Their structures were established by spectroscopic methods. These compounds seem to be minor impurities in production of the drug megestrol acetate.