Open Label Safety and Tolerability Study of COV155 in Subjects With Osteoarthritis (OA) or Chronic Low Back Pain (CLBP)

Inclusion Criteria * General good health, other than osteoarthritis (OA) or chronic low back pain (CLBP), based upon results of medical and surgical history and medical exam * ≥18 years of age * Voluntarily provide written informed consent * Female subjects eligible if 1. Not pregnant or lactating; not planning to become pregnant within next 60 days 2. Surgically sterile, or 2 years postmenopausal, or practicing acceptable birth control for more than 60 days prior to Screening and use of acceptable birth control during the study and 7 days following the last dose of COV155 * Male subjects biologically capable of having children must use reliable birth control during study and 7 days after the last dose of COV155. Surgical sterilization of the subject's monogamous partner qualifies as adequate birth control * Clinical diagnosis of one of the following 1. OA of knee or hip for at least 1 year with moderate to severe daily pain despite chronic use of stable doses of non-steroidal anti-inflammatory drugs (NSAIDs) or other non-steroidal, non-opioid therapies or with therapy including opioids 2. Moderate to severe CLBP for at least several hours a day for a minimum of 90 days, not due to a known malignancy, and classified as non-neuropathic, neuropathic, or symptomatic for more than 6 months after LBP surgery 3. OA of knee and scheduled to undergo unilateral primary tricompartmental arthroplasty. * For CLBP/OA: Average in-clinic pain score of ≥3 on 11-point (0 to 10) numerical rating scale (NRS) as an average for the last 24 hours at Screening; - Pain intensity score of ≥4 on NRS as an average for the last 24 hours at Baseline * For TKR: 11. Post-operative pain intensity scores ≥ 4 on a 0 to 10 NRS after discontinuation of post-surgical patient controlled analgesia or intravenous pain medications; body mass index ≤ 38.0; classified as either Physical Status (PS)-1 or PS-2. Exclusion Criteria * Any clinically significant condition or unstable illness that precludes study participation or interferes with assessment of pain and other symptoms of CLBP or OA or would increase the risk of opioid or NSAID related adverse events * Schizophrenia or an uncontrolled or poorly controlled major psychiatric condition or clinically significant anxiety or depression * Active malignancy or history of malignancy within 2 years prior to Screening other than dermal or cervical squamous cell carcinoma in situ * History of seizures (exception-pediatric febrile seizures) * Clinically significant ECG abnormalities or uncontrolled hypo- or hypertension * For CLBP/OA: Arthroscopic or open surgery on either the knee or hip selected as primary OA study joint within 6 months prior to Screening; - For CLBP subjects, a surgical procedure for back pain within 6 months prior to Screening, nerve or plexus block within 30 days prior to Screening or botulinum toxin injection in lower back region within 90 days prior to Screening. For OA subjects, joint injection within 30 days prior to Screening; - Surgical implants of either the knee or hip selected as the primary OA joint; history of spinal stenosis (only CLBP subjects) * For TKR: Major prior open knee surgery on same side as arthroplasty; any other surgery/elective procedures within 4 weeks of Screening, or during study; going to rehabilitation after surgery * Gastric reduction or gastric band surgery * Taking opioids in equivalents to more than 20 mg hydrocodone or more than 40 mg morphine orally per day, or taking opioid medications 4 days a week or more * Known allergy or hypersensitivity to opioids, acetaminophen or ibuprofen * Certain lab abnormalities * Unable to discontinue use of prohibited medications or history of substance or alcohol abuse within 2 years prior to Screening or positive urine drug test at Screening for alcohol, illicit drugs (including medical cannabis) or controlled substances other than prescribed medications * Positive for human immunodeficiency virus, hepatitis B (surface antigen), and/or hepatitis C * Any other chronic pain condition other than CLBP or OA that would interfere with the assessment of CLBP or OA * Used a monoamine oxidase inhibitor, antipsychotic, or benzodiazepine within 14 days prior to Screening or started or changed doses of anticonvulsants, selective serotonin reuptake inhibitors, serotonin norepinephrine reuptake inhibitors, or tricyclic antidepressants within 30 days prior to Screening * Previously received COV155 in a study * Received any investigational drugs or devices within 30 days prior to Screening * Other criteria as specified in the protocol