This study evaluates intravenous (IV) buprenorphine versus IV morphine for the management of severe, acute pain among emergency department (ED) patients. ED patients with severe pain will be randomized in equal proportion to receive IV buprenorphine or IV morphine.

Buprenorphine is classified as a partial mu opioid agonist and a weak kappa antagonist. In lower doses, buprenorphine has an analgesic potency 25 to 40 times more potent than similar milligram dosages of morphine. Consistent with its partial agonist activity, an apparent ceiling effect for opioid-induced ventilatory impairment has been demonstrated. These properties would suggest that buprenorphine is an effective analgesic with a favorable safety profile.

Objective: The objective of this study is to determine if there is a clinically significant difference in reduction of pain scores, measured by the Numeric Rating Scale (NRS), between intravenous (IV) buprenorphine and IV morphine for severe pain in patients presenting to the Alameda Health System--Highland Hospital ED. The investigators are evaluating if IV buprenorphine is non-inferior to IV morphing. The investigators hypothesize that buprenorphine will provide equivalent analgesic effects as morphine at 60 minutes, with a lower proportion of medication adverse effects.

Study Design: This is a double-blinded, randomized controlled non-inferiority trial comparing the analgesic efficacy of intravenous buprenorphine versus intravenous morphine for ED patients presenting with severe, acute pain.

Participants: ED patients aged ≥18 years old who present with severe (pain NRS ≥7), acute pain warranting (according the treating provider's judgment) and able to receive IV opioid analgesia. The investigators will exclude pregnant patients, patients deemed too critically ill by the provider, patients with allergy to buprenorphine or morphine, patients in custody, patients on methadone, patients who have taken/received short acting opioid medications in the last 12 hours, and patients who have taken/received long acting opioid medication in the past 24 hours.

Intervention: In arm A, patients will receive IV Buprenorphine 0.3mg diluted to a volume of 10mL with NS in a plastic syringe administered over 3-5 minute. In arm B, patients will receive IV morphine 0.1mg/kg (max 10mg) over 3-5 minutes. In both arms, at 20 minutes the patient will be asked "would you like more pain medication?" If he/she answers "yes", then he/she will receive a second dose of the same amount of medication they previously received based on the randomized arm they were placed into. At the end of the study time, 60 minutes, the patient's ongoing pain management will be left to the attending physician caring for the patient in the ED.

Data Collection: For both arms, the patients' NRS pain scores and adverse effects will be queried at times 0, 10min, 20 min, 30min, 40min, 50 min, and 60 min. Demographic and comorbidity data points will be abstracted during or after the study's conclusion.

Inclusion Criteria:

• ED patients with acute pain NRS ≥7 warranting IV opioid analgesia (according to ED provider)

Exclusion Criteria:

• Patient refusal

• pregnancy

  • level 1 trauma patients
  • patients deemed critically ill by provider
  • patients in custody
  • patients on methadone
  • Patients who have received or taken any short acting opioid medication in the past 12 hours.
  • Patients who have received or taken any long acting opioid medication in the past 24 hours.

The provider, nurse administering the medication, patient, and research assistant will be masked to the randomization and the drug provided. We will ensure masking by the following mechanisms: drugs will be prepared by the pharmacy staff in identical 10mL syringes; the medication will be diluted to a volume of 10mL with normal saline (NS); and both medications are clear so the syringes will appear identical. Both drugs will be administered over the same period of time, 3-5 minutes.