This Phase 1, multicenter, open-label, randomized, bupivacaine-controlled study is designed to evaluate the pharmacokinetics (PK) and safety of EXPAREL vs. bupivacaine HCl for postsurgical analgesia in pediatric subjects aged 0 to less than 6 years of age undergoing cardiac surgery, utilizing local infiltration analgesia (LIA).

This study will be conducted in 3 Parts (Part 1, Part 2, and Part 3) and a total of approximately 48 male and female subjects will be enrolled.

Part 1 will enroll approximately 16 subjects, aged 2 to less than 6 years to obtain information on PK and safety. Subjects will be randomized 1:1 (8 EXPAREL subjects and 8 bupivacaine HCl subjects) to receive either a single dose of EXPAREL 4 mg/kg (not to exceed a maximum total dose of 266 mg) or 0.25% bupivacaine HCl 2 mg/kg (not to exceed a maximum total dose of 175 mg) using LIA. The overall PK and safety profiles from Part 1 will be completed, analyzed, and reviewed to establish an appropriate study drug dose for Part 2.

Subject enrollment for Part 2 will commence upon complete enrollment of Part 1, establishment of an appropriate study drug dose from the PK, and safety analysis of Part 1 and Data Safety Monitoring Board (DSMB) recommendations to proceed to Part 2. Part 2 will enroll approximately 16 subjects, aged 6 months to less than 2 years to obtain information on PK and safety. Subjects will be randomized 1:1 (8 EXPAREL subjects and 8 bupivacaine HCl subjects) to receive either a single dose of EXPAREL or 0.25% bupivacaine HCl using LIA. The overall PK and safety profiles from Part 2 will be completed, analyzed, and reviewed to establish an appropriate study drug dose for Part 3.

Subject enrollment for Part 3 will commence upon complete enrollment of Part 2, establishment of an appropriate study drug dose from the PK and safety analysis of Part 2, and DSMB recommendations to proceed to Part 3.

Part 3 will enroll approximately 16 subjects aged 0 to less than 6 months to obtain information on PK and safety. Subjects will be randomized 1:1 (8 EXPAREL subjects and 8 bupivacaine HCL subjects) to receive either a single dose of EXPAREL or 0.25% bupivacaine HCl using LIA.

Inclusion Criteria:

All of the following inclusion criteria must be met for eligibility:

1. Pediatric participants with congenital heart defects planned to undergo cardiac surgery with cardiopulmonary bypass
2. Male or female participants from 0 to less than 6 years of age on the day of surgery: 2 years to less than 6 years of age for Part 1; 6 months to less than 2 years of age for Part 2; 0 to less than 6 months of age for Part 3
3. American Society of Anesthesiologists (ASA) Classes 1 through 4.
4. Parent/guardian is able to speak, read, and understand the language of the ICF and provide informed consent for the participant.
5. Parent/guardian is able to adhere to the study visit schedule and complete all study assessments for the participant.

Exclusion Criteria:

Exclusion Criteria:

A participant will not be eligible for the study if any of the following exclusion criteria are met:

1. History of hypersensitivity or idiosyncratic reactions or contradictions to EXPAREL, bupivacaine HCl, or other amide-type local anesthetics or to opioid medications
2. Administration of EXPAREL or bupivacaine HCl within 30 days prior to IP administration
3. Administration of an IP within 30 days or 5 elimination half-lives of such IP, whichever is longer, prior to IP administration, or planned administration of another IP or procedure during participation in this study
4. History of preterm birth (before 35 weeks of pregnancy)
5. History of coagulopathies or immunodeficiency disorders
6. Disease or condition that, in the opinion of the Investigator, indicates an increased vulnerability to IPs and/or procedures
7. Recent or potential exposure to COVID-19
8. Cardiac surgery has been canceled and cannot be rescheduled within 30 days of signing the ICF because of any reason.
9. Necessity in delayed wound closure
10. Informed consent withdrawn before randomization