A Study Evaluating Pain Relief and Safety of Orally Administered CR845 in Patients With Osteoarthritis of Hip or Knee

Inclusion Criteria: 1. Voluntarily provides written informed consent to participate in the study prior to any study procedures. 2. Is able to speak, read, and communicate clearly in English or Spanish; is able to understand the study procedures. 3. Male or female ≥ 25 years of age. 4. Body mass index (BMI) ≤ 40 kg/m2. 5. Has OA of the hip or knee according to American College of Rheumatology (ACR) criteria. 6. Reports an average pain intensity level ≥ 5 in the index joint at Screening on a 0-10 NRS scale. 7. Is either opioid-naïve (defined as taking \< 10 mg a day of morphine equivalent 14 days prior to screening) or opioid-experienced. If receiving opioid analgesic medication for OA, patients must be on a stable dose ≤ 40 mg of morphine equivalents for 14 days prior to screening. 8. Willing to discontinue currently used pain medications beginning 5 days prior to the Baseline Visit and throughout the study. Acetaminophen use is allowed. (Section 8.8) 9. If female: 1. Of childbearing potential - the patient must be willing to practice an acceptable form of birth control (defined as the use of an intrauterine device, a barrier method with spermicide, condoms, any form of hormonal contraceptives, or abstinence from sexual intercourse) for the duration of treatment and for at least 3 days following the last dose of study drug. 2. Of non-childbearing potential - the patient must be surgically or biologically sterile (hysterectomy, bilateral oophorectomy, bilateral tubal ligation, or postmenopausal for at least 1 year). 10. If male, the patient must be surgically or biologically sterile. If not sterile, the patient must agree to use an acceptable form of birth control with a heterosexual partner (as described in inclusion criterion #9) or abstain from sexual relations during the treatment period and for 3 days following the last dose of study drug. 11. Is free of other physical, mental, or medical conditions that, in the opinion of the Investigator, would make study participation inadvisable. 12. Reports a daily pain intensity score in the index joint ≥ 5 (on a 0-10 NRS scale) during 4 or more of the last 7 days prior to randomization, with 2 consecutive days ≥ 5 occurring just prior to randomization Exclusion Criteria: Inclusion Criteria: A patient will be eligible for enrollment if the following criteria are met: 1. Voluntarily provides written informed consent to participate in the study prior to any study procedures. 2. Is able to speak, read, and communicate clearly in English or Spanish; is able to understand the study procedures. 3. Male or female ≥ 25 years of age. 4. Body mass index (BMI) ≤ 40 kg/m2. 5. Has OA of the hip or knee according to American College of Rheumatology (ACR) criteria. 6. Reports an average pain intensity level ≥ 5 in the index joint at Screening on a 0-10 NRS scale. 7. Is either opioid-naïve (defined as taking \< 10 mg a day of morphine equivalent 14 days prior to screening) or opioid-experienced. If receiving opioid analgesic medication for OA, patients must be on a stable dose ≤ 40 mg of morphine equivalents for 14 days prior to screening. 8. Willing to discontinue currently used pain medications beginning 5 days prior to the Baseline Visit and throughout the study. Acetaminophen use is allowed. (Section 8.8) 9. If female: 1. Of childbearing potential - the patient must be willing to practice an acceptable form of birth control (defined as the use of an intrauterine device, a barrier method with spermicide, condoms, any form of hormonal contraceptives, or abstinence from sexual intercourse) for the duration of treatment and for at least 3 days following the last dose of study drug. 2. Of non-childbearing potential - the patient must be surgically or biologically sterile (hysterectomy, bilateral oophorectomy, bilateral tubal ligation, or postmenopausal for at least 1 year). 10. If male, the patient must be surgically or biologically sterile. If not sterile, the patient must agree to use an acceptable form of birth control with a heterosexual partner (as described in inclusion criterion #9) or abstain from sexual relations during the treatment period and for 3 days following the last dose of study drug. 11. Is free of other physical, mental, or medical conditions that, in the opinion of the Investigator, would make study participation inadvisable. 12. Reports a daily pain intensity score in the index joint ≥ 5 (on a 0-10 NRS scale) during 4 or more of the last 7 days prior to randomization, with 2 consecutive days ≥ 5 occurring just prior to randomization Exclusion Criteria: 1. Has had a joint replacement in the index joint. 2. Has received an intra-articular injection of corticosteroids or hyaluronic acid in the index joint within 3 months prior to the Screening Visit. 3. Has started a new medication for chronic illness within 30 days prior to the Screening Visit. 4. Is receiving opioid analgesic treatment for OA of the hip or knee at a dose \> 40 mg of morphine equivalent. 5. Uses antipsychotics, antiepileptics, sedatives, hypnotics, or antianxiety agents, selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants with a dose change \<30 days prior to day 1 of the study. 6. Has a history or current diagnosis of substance dependence (except caffeine or nicotine) or alcohol abuse, according to the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). 7. Has a positive urine drug screen for drugs of abuse at Screening. 8. Has been diagnosed with a condition of hyperhidrosis (excessive sweating) or primary hypodipsia (a reduced sense of thirst). 9. Has a history (within 6 months) of clinically meaningful orthostatic changes in vital signs OR, at Screening, has a decrease in systolic blood pressure by \> 20 mm Hg or a decrease in diastolic blood pressure by 10 mm Hg together with an increase in heart rate of \> 30 beats per minute when transitioning from supine to standing measurements. 10. Has a medical condition (e.g., a cardiovascular, pulmonary, hepatic, renal, hematologic, gastrointestinal, endocrine \[adrenal hyperplasia\], immunologic, dermatologic, neurologic, oncologic, or psychiatric) or a significant laboratory abnormality that, in the Investigator's opinion, would jeopardize the safety of the patient or is likely to confound the study measurements. 11. Has had any gastric bypass surgery (for weight loss). 12. Has a corrected QT interval of \>450 msec in males, \>470 msec in females, or clinically significant abnormality on screening ECG. 13. Has a serum sodium level \> 143 mmol/L at Screening. 14. Has impaired renal function indicated by serum creatinine \> 2 × the reference upper limit of normal (ULN). 15. Has a serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \> 2.5 × the reference ULN, or total bilirubin \> 2 × the ULN at Screening. 16. Has, in the opinion of the Investigator, any clinical signs of dehydration or hypovolemia (e.g., symptomatic hypotension) or associated laboratory abnormalities (e.g., elevated hematocrit or elevated blood urea nitrogen \[BUN\] \> 1.5 × the reference ULN) at Screening. 17. Has taken opioid or non-opioid pain medication (e.g., nonsteroidal anti-inflammatory drugs \[NSAIDs\] such as naproxen or cyclooxygenase-2 inhibitors) within 5 days prior to study drug administration. Acetaminophen use is allowed. (Section 8.8) 18. Has received another investigational drug within 30 days prior to Baseline or has planned to participate in another clinical trial while enrolled in this study.