This is a Phase-1, single center, randomized, double-blind, active and placebo-controlled study in approximately 54 adult healthy subjects (Cohort 1, Cohort 2, and Cohort 3). Eighteen subjects will be enrolled in each of the 3 cohorts.~Subjects in Cohort 1, Cohort 2, and Cohort 3 will be randomized 1:1:1 with 6 subjects receiving Liposomal Bupivacaine 13.3 intrathecal (IT), 6 subjects receiving bupivacaine IT, and 6 subjects receiving placebo IT in each cohort.~The dose of Liposomal Bupivacaine 13.3 (and volume of injectate across all three treatment arms) will be determined by the cohort. Cohort 1 subjects randomized to the Liposomal Bupivacaine 13.3 arm will be dosed 2 mL (26.6 mg) of Liposomal Bupivacaine 13.3, Cohort 2 subjects randomized to the Liposomal Bupivacaine 13.3 arm will be dosed 3 mL (39.9 mg) of Liposomal Bupivacaine 13.3, and Cohort 3 subjects randomized to the Liposomal Bupivacaine 13.3 arm will be dosed 4 mL (53.2 mg) of Liposomal Bupivacaine 13.3.~The dose of bupivacaine IT administered in all cohorts will be 15 mg. Cohort 1 subjects randomized to the bupivacaine arm will be dosed 2 mL (7.5 mg/ 1 mL) of 0.75% bupivacaine. Cohort 2 subjects randomized to the bupivacaine arm will be dosed 2 mL (7.5 mg/ 1 mL) of 0.75% bupivacaine mixed with 1 mL of preservative free normal saline to create a total volume of solution administered of 3 mL. Cohort 3 subjects randomized to the bupivacaine arm will be dosed 2 mL (7.5 mg / 1 mL) of 0.75% bupivacaine mixed with 2 mL of preservative free normal saline to create a total volume of solution administered of 4 mL.~Cohort 1 subjects randomized to the placebo arm will be dosed 2 mL of preservative free normal saline. Cohort 2 subjects randomized to the placebo arm will be dosed 3 mL of preservative free normal saline. Cohort 3 subjects randomized to the placebo arm will be dosed 4 mL of preservative free normal saline.~The decision to proceed to the next cohort will be made following a full review of the safety, PK, sensory, motor, neurological history and assessment questionnaires, comprehensive neurological exam and Adverse Event data from the current completed cohort(s).~All subjects will remain in the Early Phase Research Unit (EPRU) for 5 days after drug administration and will be discharged on Day 6. Subjects will be instructed to return to the research facility for a Day 9 follow-up visit. Subjects will also receive a phone call on Day 30 (±3 days) to assess safety.
Primary Objective: To assess the safety and tolerability of Liposomal Bupivacaine 13.3 administered as a single intrathecal injection in healthy volunteers.~Secondary Objective: To characterize the pharmacokinetic (PK) and pharmacodynamic (PD) profile of Liposomal Bupivacaine 13.3 administered as a single intrathecal injection in healthy volunteers.