- Group 2: Active bupivacaine HCl TAP infiltration following spinal anesthesia On Day 1, prior to the C-section, all subjects will receive an intrathecal injection of 150 mcg morphine (eg, Duramorph®) as standard of care in conjunction with single-shot spinal anesthesia (1.4-1.6 mL bupivacaine HCl 0.75%) plus 15 mcg intrathecal fentanyl. A combined spinal epidural (CSE) anesthesia technique may also be used provided the epidural component is not used.