Correct spelling for the English word "Alfathesin" is [ˈalfəθˌɛsɪn], [ˈalfəθˌɛsɪn], [ˈa_l_f_ə_θ_ˌɛ_s_ɪ_n] (IPA phonetic alphabet).
I apologize, but I couldn't find any information on "Alfathesin". It seems to be a word that does not exist in the English language or has very limited usage.