Low recruitment numbers and study funding will be closing shortly.

This is a pilot, double-blind, placebo-controlled randomized clinical trial of individuals with opioid use disorder (OUD) with suicidal ideation in the emergency department (ED) to receive either a single infusion of ketamine 0.8mg/kg (n=25) or saline placebo (n=25). The primary aim is to evaluate the safety of the ketamine treatment. The secondary aim is to determine the preliminary efficacy of opioid- and suicide-related outcomes.

Individuals with opioid use disorder (OUD) seeking medical care in the emergency department (ED) will be first evaluated as per usual clinical care by the ED staff, including any acute medical treatment for overdose or any other acute medical issues needing treatment. For those who endorse suicidal ideation, after medical clearance, the standard medical care will involve the evaluation of patients by the psychiatry consult service in the ED. Patients evaluated by psychiatry who require further behavioral health care and do not have acute medical issues remain in the ED awaiting admission to an inpatient psychiatry unit or other linkages to care. Potential participants will be approached after the psychiatry evaluation is complete and a decision has been made to keep the patients in the ED for continued psychiatric care or admit them medically. After applying the full inclusion and exclusion criteria, those who remain eligible will be randomized to receive in a double-blind fashion either a single infusion of ketamine (0.8mg/kg) or a saline placebo. Safety assessments will be conducted during and after the receipt of ketamine or placebo, and at follow-up assessments after discharge from the emergency department of the hospital following inpatient psychiatric treatment.

Inclusion/Exclusion Criteria:

To be eligible, individuals must be/have:

• English speaking adults aged 18 and above
• Diagnosed with DSM5 opioid use disorder, moderate or severe, or clinically suspected opioid use disorder
• Endorsing suicidal ideation sufficiently severe to meet criteria for referral to an inpatient psychiatric facility or a crisis stabilization unit
• Any prior history of an opioid overdose
• Medically cleared

Individuals with any of the following will be excluded:

• Any psychotic disorder or active homicidally
• Inability to perform consent due to impaired mental status
• Current substance intoxication or current (or within the past 1-month) mania, hypomania, mixed-episode, or psychosis
• Systolic blood pressure persistently elevated above 160mmHg, diastolic blood pressure greater than 100 mmHg, or heart rate >100bmp, in the ED
• Clinical Opioid Withdrawal Scale (COWS) score of 12 or greater
• History of hypersensitivity to ketamine, or experience of emergence reaction
• History of hypersensitivity to ondansetron or concurrently using apomorphine
• History of any illicit or recreational use of ketamine in the past 12 months
• Receipt of ketamine treatment for depression in the past 3 months
• History of DSM5 hallucinogen use disorder, intracranial mass or bleed, porphyria, thyrotoxicosis, seizure disorder other than from alcohol withdrawal, liver cirrhosis, or sleep apnea
• Cardiac or EKG abnormalities based on history, physical examination or the baseline EKG
• History within 6 months of thoracic surgery, lung cancer, head trauma, stroke, or myocardial infarction
• Liver dysfunction with LFTs >3x upper normal limit
• Current use of medications with known drug-drug interactions with ketamine (i.e., St. John's Wort, theophylline, opioid analgesics other than buprenorphine and methadone for the treatment OUD, Central Nervous System (CNS) depressants other than benzodiazepines or phenobarbital)
• Pregnant
• Patients who are breastfeeding
• ASA class 3 or greater or documented history of difficult airway in HER
• Active exacerbation of COPD or asthma
• Currently participating or anticipated to participate in a concurrent investigational clinical trial
• High risk for adverse emotional or behavioral reaction based on the opinion of the study investigators, including evidence of a personality disorder

Participants will then be randomized in a double-blind fashion to receive either ketamine (0.8 mg/kg) or a matched volume saline placebo in the ED. Randomization will use a permuted block method58. The randomization ratio will be 1:1. A biostatistician will generate the randomization codes and provide the randomization list to the hospital's Investigational Drug Services (IDS). The study RA will contact IDS once the participant has signed informed consent and IDS staff will randomize participants. Both RA, study team and the clinical team will be blinded to the allocation.