Primary objective: The primary objective of this study is to evaluate the pharmacokinetics (PK) of EXPAREL in pediatric subjects 12 to less than 17 years of age undergoing spinal surgery.

Secondary objective: The secondary objective of this study is to evaluate the safety of EXPAREL in pediatric subjects 12 to less than 17 years of age undergoing spinal surgery.

This is a Phase 1, single-center, open-label study designed to evaluate the safety and PK profile of EXAPREL when administered intraoperatively at the end of surgery via local infiltration. Fifteen pediatric subjects 12 to less than 17 years of age undergoing spinal surgeries are planned for enrollment.

Subjects will be screened within 30 days prior to study drug administration. During the screening visit, subjects will be assessed for past or present neurologic, cardiac, and general medical conditions that, in the opinion of the investigator, would preclude them from study participation.

Subjects will undergo their pre-planned spinal surgeries per the institution's standard of care. On Day 1, eligible subjects will receive a single dose of EXPAREL 4 mg/kg intraoperatively at the end of surgery via local infiltration into the surgical site. There is no required length of stay in the hospital; subjects may be discharged based on the medical judgment of the treating physician.

A follow-up phone call will be scheduled for all subjects on Day 7. A final follow-up visit will be made on Day 30 to all subjects who received study drug.

Inclusion Criteria:

1. Subjects whose parent(s) or guardian(s) has/have signed and dated an informed consent form for the subject to participate in the study, and subjects who have provided written assent to participate in the study (if capable).
2. American Society of Anesthesiologists (ASA) Class 1-3.
3. Male or female subjects 12 to less than 17 years of age on the day of surgery.
4. Body mass index (BMI) at screening within the 20th to 80th percentile for age and sex.
5. A pregnancy test for female subjects of childbearing potential will be conducted in the preoperative holding area according to the study site's standard of care. A negative result for the pregnancy test must be available prior to the start of surgery.
6. Subjects and their parent(s)/guardian(s) must be able to speak, read, and understand the language of the ICF and any instruments used for collecting subject-reported outcomes in order to enable accurate and appropriate responses to study assessments, and provide informed consent/assent.
7. Subjects must be able to adhere to the study visit schedule and complete all study assessments.

Exclusion Criteria:

1. Contraindication to bupivacaine or other amide-type local anesthetics or to opioid medication.

2. Administration of EXPAREL or bupivacaine HCl within 30 days prior to study drug administration.

3. Subjects with coagulopathies or immunodeficiency disorders.

4. Administration of an investigational drug within 30 days or 5 elimination half-lives of such investigational drug, whichever is longer, prior to study drug administration, or planned administration of another investigational product or procedure during the subject's participation in this study.

   In addition, the subject will be ineligible to receive study drug if the following criterion is met during surgery:

5. Any clinically significant event or condition uncovered during the surgery (eg, excessive bleeding, acute sepsis) that might render the subject medically unstable or complicate the subject's postsurgical course.