A Phase 2 Study to Evaluate Analgesic Effect of IV CR845 For Pain Following Bunionectomy Surgery

Inclusion Criteria: 1. Able to provide written informed consent prior to any study procedures; 2. Able to communicate clearly with the Investigator and staff; 3. Males and females aged 18 years or older; 4. Scheduled for elective primary unilateral first metatarsal bunionectomy surgery (osteotomy and internal fixation) with no collateral procedures; 5. Females physically incapable of childbearing potential (postmenopausal for more than 1 year or surgically sterile) or practicing an acceptable method of contraception (hormonal, barrier with spermicide, intrauterine device, vasectomized partner, or abstinence). Subjects using hormonal birth control must have received at least 1 cycle of treatment prior to randomization. All females of childbearing potential must have a negative pregnancy test and not be breast feeding at Baseline; 6. Negative urine drug screen for drugs of abuse at Screening and at Baseline; a positive drug screen result may be permitted if the patient has been on a stable dose of an allowed medication for \>30 days (antipsychotics, antiepileptics, sedatives, hypnotics, or antianxiety agents, selective serotonin reuptake inhibitors \[SSRIs\], tricyclic antidepressants) or \>3 months (opioid analgesics or systemic steroids); 7. American Society of Anesthesiologists (ASA) risk class of I to II; 8. Body weight \<170 kg Exclusion Criteria: 1. Has known allergies to opioids, unless has subsequently tolerated other opioids and in the opinion of the PI could tolerate study drug; 2. Has a known or suspected history of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)-diagnosed alcohol, opiate or other drug abuse or dependence within 12 months prior to screening; 3. Is unable to refrain from alcohol consumption for a period beginning 24 hours prior to surgery through the end of the Treatment Period; 4. Has taken non-opioid analgesics (including cyclooxygenase-2 \[COX-2\] inhibitors) or nonsteroidal anti-inflammatory drugs (NSAIDs) within 12 hours of the Baseline assessments; 5. Has taken any opioid analgesics or used systemic steroids within 4 days of surgery OR has been using opiates chronically for a period of \< 3 months; (Note: Patients on stable chronic opioids for ≥ 3 months will need to discontinue them for 4 days prior to surgery); 6. Has used antipsychotics, antiepileptics, sedatives, hypnotics, or antianxiety agents, selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants for \< 30 days prior to surgery or had a dose change within the previous 30 days; 7. Has taken any prescription or over-the-counter medication within 4 days prior to surgery that, in the opinion of the Investigator, is expected to confound the analgesic response; 8. Has taken herbal agents or nutraceuticals (i.e., chaparral, comfrey, germander, jin bu huan, kava, pennyroyal, skullcap, St. John's wort, or valerian) during any of the 7 days prior to surgery; 9. Has any clinically significant condition or a significant laboratory abnormality that would, in the Investigator's or designee's opinion, preclude study participation 10. Has received another investigational drug within 30 days of scheduled surgery.