Neuropathic pain associated with diabetic peripheral neuropathy

Inclusion Criteria

- Adults ≥ 18 years of age at the time of signing the informed consent.
- At the time of screening, have documented diagnosis of type 1 OR type 2 diabetes mellitus (DM) with painful distal symmetrical sensorimotor neuropathy of more than 6 months duration according to modified Toronto Clinical Neuropathy Score.
- Weekly mean 24-hour average pain NRS ≥ 4 with adequate variability (not the same score on all daily pain ratings) and compliance (non-missing pain score on at least 6 out of 7 consecutive days) in daily pain recording during the 7 day NRS baseline period.
- Neuropathic pain according to the DN4 questionnaire (Douleur Neuropathique 4 Questions).
- Women of childbearing potential must agree to use acceptable effective or highly effective birth control methods.

Exclusion Criteria

- Any differential diagnosis of peripheral diabetic neuropathy (PDN) including but not limited to other neuropathies (e.g. vitamin B12 deficiency, Chronic Inflammatory Demyelinating Polyneuropathy), polyradiculopathies, central disorders (e.g. demyelinating disease), or rheumatological disease (e.g. foot arthritis, plantar fasciitis).
- Any other diseases or conditions that according to the investigator can compromise the function of the body systems and could result in altered absorption, excessive accumulation, impaired metabolism, or altered excretion of the study intervention (e.g. chronic bowel disease, Crohn's disease and ulcerative colitis).
- Any serious or unstable diseases or conditions including psychiatric disorders that might interfere with the conduct of the study or the interpretation of the results.
- Major surgery or radiological procedures (e.g. PTA (Percutaneous transluminal angioplasty) and stenting of peripheral vascular lesions in lower extremities) within 3 months before screening visit or scheduled during the study period, which might interfere pain response evaluation.
- Symptomatic peripheral arterial disease in lower or upper extremities, including diabetic ulcers.
- Previous use of strong opioids (e.g. oxymorphone, oxycodone) for neuropathic pain anytime, or topical use of capsaicin within 3 months prior to the screening visit.
- History or current diagnosis of electrocardiogram (ECG) abnormalities indicating significant risk of safety for study participants.
- Moderate-to-severe hepatic impairment defined as Child-Pugh Class B or C.
- Have platelets ≤ 100 x 109/L, or neutrophil count < 1.2 x 109/L (or equivalent), hemoglobin ≤ 100 g/L for women or hemoglobin ≤ 110 g/L for men at screening.
- Glycemic control unstable (hemoglobin HbA1c ≥11%) within 3 months prior to screening (e.g. ketoacidosis requiring hospitalization, any recent episode of hypoglycemia requiring assistance through medical intervention, uncontrolled hyperglycemia).
- ALT >2xULN, or AST >2xULN, or total bilirubin greater than ULN, or alkaline phosphatase (AP) >2xULN, or INR greater than ULN (unless related to anticoagulation treatment) at screening.
- Positive hepatitis B virus surface antigen (HBsAg) or positive hepatitis C virus antibodies (anti-HCV) and detection of mRNA (HCV-mRNA tested only if hepatitis C virus antibodies detected).
- Estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m^2 calculated by Modification of Diet in Renal Disease (MDRD) formula (local formulas will be used where applicable.
- Uncontrolled hypertension despite optimal treatment with antihypertensive(s), indicated by a sitting systolic blood pressure ≥ 180 mmHg and/or diastolic blood pressure ≥ 110 mmHg.