Correct spelling for the English word "phesin" is [fˈɛsɪn], [fˈɛsɪn], [f_ˈɛ_s_ɪ_n] (IPA phonetic alphabet).
Acetphenetidin-sodium-sulphonate, a sulpho-derivative of acetphenetidin; a light brownish red odorless powder, soluble in water; antipyretic and analgesic in doses of gr. 8-15 (0.5-1.0).
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.