This is a multiple-dose, randomized, placebo-controlled crossover study of the efficacy and safety of XP19986 SR1 in subjects with spasticity due to spinal cord injury. Three cohorts of subjects are randomized to receive XP19986 SR1 10 mg every 12 hrs or 20 mg every 12 hrs or 30 mg every 12 hrs in one treatment segment and placebo every 12 hrs in the alternate treatment segment. Each subject serves as their own control in this cross-over study.