Intravenous Acetaminophen for Craniotomy Patients

Inclusion Criteria: * At least 18 years of age * Weigh at least 50 kg (110.23 lbs) * Undergoing open, elective intracranial procedure for * tumor resection * aneurysm clipping * revascularization * Have an ASA (American Society of Anesthesiologists) physical status of 1, 2, 3, or 4 * Able to provide written informed consent Exclusion Criteria: * Significant medical disease, laboratory abnormality, or condition that, in the opinion of the investigator, would compromise patient welfare or would otherwise contraindicate study participation * Unable to communicate symptoms * Current daily opioid use (\>40 mg morphine equivalent) * Tramadol use * Treated with MAO (monoamine oxidase inhibitors) inhibitors within 10 days of surgery * Treated with any amount of acetaminophen within 8 hours of anesthesia for surgery * Allergic or hypersensitive to acetaminophen or any contraindications per manufacturer's guidelines * Pregnancy * Impaired liver function * Participation in interventional clinical study within the last 30 days * Known or suspected history of alcohol or drug abuse * Surgery for resection of acoustic neuroma * Transphenoidal tumor resection