The present invention is directed to two new polymorph Form V and Form F
of desvenlafaxine succinate, to processes of their preparations,
pharmaceutical composition comprising such materials and their use in
therapy. Form V is prepared from recrystallizing desvenlafaxine succinate
in a mixture of tetrahydrofuran and ethanol. Form F is obtained from
recrystallization of desvenlafaxine succinate in a mixture of cyclohexane
and polar solvents such as ethanol, THF, methanol or isopropyl alcohol.