Potential participants will be screened at the time of outpatient clinic visits. Patients who require operative intervention for management of their colonic disease, both malignant and non-malignant, are eligible for enrollment. Individuals who present to the emergency department and are evaluated by the previously mentioned divisions will be screened for eligibility. If a potential participant qualifies for enrollment, he or she will be approached by one of the IRB approved study staff for consent. Prior to randomization and formal enrollment, an investigational drug services pharmacist will screen for any contraindication to potential ketamine therapy. Following investigator and pharmacy approval, patients will be randomized by the Investigational Drug Services (IDS). The two trial arms will be randomized in a 1:1 control to experimental fashion with randomization blocks conducted in sets of 4 patients.