This randomized controlled clinical trial evaluates the effect of preemptive analgesia on postoperative pain outcomes in adult patients undergoing orthognathic surgery. Participants scheduled for bilateral sagittal split osteotomy and Le Fort I osteotomy under general anesthesia will be randomized to one of three groups: intravenous acetaminophen, intravenous ibuprofen, or a control group receiving standard postoperative analgesia without preoperative medication.

The study aims to determine whether the administration of pre-surgical analgesics reduces postoperative pain intensity and analgesic requirements during the early postoperative period. Pain will be assessed using a standardized pain scale at multiple time points following surgery, and secondary outcomes will include postoperative analgesic consumption and patient satisfaction with pain control.

This investigation seeks to contribute evidence supporting multimodal analgesic strategies and improved postoperative pain management in patients undergoing orthognathic surgery.

Effective management of postoperative pain remains an important component of perioperative care in patients undergoing orthognathic surgery. Procedures such as bilateral sagittal split osteotomy and Le Fort I osteotomy are associated with significant postoperative discomfort due to extensive manipulation of osseous and soft tissue structures. Preemptive analgesia, defined as the administration of analgesic medication prior to surgical injury, has been proposed as a strategy to attenuate central sensitization and reduce postoperative pain intensity.

This study is designed as a participant-blinded, randomized controlled clinical trial conducted in the operating room at the Administration of Medical Services in Puerto Rico (ASEM). Adult patients between 21 and 65 years of age with American Society of Anesthesiologists (ASA) physical status I or II who are scheduled to undergo orthognathic surgery will be invited to participate following informed consent. A total of 72 participants will be enrolled and randomly assigned in a 1:1:1 ratio to one of three groups: intravenous acetaminophen, intravenous ibuprofen, or a control group receiving no preoperative analgesic intervention.

Participants in the intervention groups will receive either acetaminophen 1 g intravenously or ibuprofen 600 mg intravenously approximately 30 minutes before surgical incision, with a second dose administered near the end of the procedure according to the medication half-life. The control group will receive no pre-surgical analgesic administration and will follow the institution's standard postoperative pain management protocol.

Postoperative pain intensity will be measured using a validated pain scale at predetermined intervals during the postoperative period. Additional outcomes include postoperative analgesic requirements and patient satisfaction with pain control. By comparing two commonly used intravenous analgesic medications with standard care, this study aims to evaluate the effectiveness of preemptive analgesic strategies in improving postoperative pain outcomes and reducing analgesic consumption following orthognathic surgery.

Inclusion Criteria:

• Adults aged 21 to 65 years.
• American Society of Anesthesiologists (ASA) physical status I or II.
• Scheduled to undergo orthognathic surgery including bilateral sagittal split osteotomy and Le Fort I osteotomy under general anesthesia.
• Ability to understand the study procedures and provide written informed consent.

Exclusion Criteria:

• Pregnancy or breastfeeding.
• Known allergy or intolerance to acetaminophen, ibuprofen, or other nonsteroidal anti-inflammatory drugs (NSAIDs).
• Renal dysfunction, defined as estimated glomerular filtration rate <60 mL/min/1.73 m².
• Hepatic dysfunction, defined as liver enzyme levels greater than twice the upper limit of normal.
• History of bleeding disorders or coagulopathy.
• Active or recent peptic ulcer disease.
• Current use of recreational drugs, including cannabis, that in the judgment of the investigators could interfere with anesthesia management, postoperative pain assessment, or study outcomes.
• Any medical condition that, in the judgment of the investigators, would make participation unsafe or interfere with study participation.

Individual participant data will not be shared because the dataset contains potentially identifiable health information and the study protocol does not include provisions for external data sharing.

Participants will be blinded to their group allocation. The anesthesiologist administering the study medication in the operating room will not be blinded due to the need to prepare and administer the assigned intervention. Postoperative pain assessments and data collection will be performed by research personnel who are blinded to treatment allocation to minimize assessment bias.