A prospective open-label clinical trial to decrease the incidence of expected side effects of oral ketamine dose administered presurgery and postsurgery, in 10 subjects undergoing elective amputation of the lower extremity. The primary outcome measure is the incidence of adverse events. Secondary outcome measures are decreased acute pain levels and decreased incidence of stump and phantom limb pain at 6 months. Enrollment of participants will occur at Rush University Medical Center (Rush), Chicago, IL. Consented participants will be included in the study undergoing elective amputation of the lower extremity from all causes.