Several studies have shown that adding dexmedetomidine or epinephrine to single-dose spinal analgesia preparations improves the length and/or speed of onset of the sensory block and post-operative pain management without increased negative side effects. To date, however, no study has compared adjunctive intrathecal dexmedetomidine to adjunctive intrathecal epinephrine in single-dose spinal analgesia. The purpose of this study is to determine if adjunctive intrathecal dexmedetomidine is non-inferior to adjunctive intrathecal epinephrine in providing better single-dose spinal analgesia during cesarean section.