Age: 19+
Healthy Volunteers: Not accepted
Inclusion Criteria:
1. Age >18 years old.
2. Estimated life expectancy greater than 12 weeks.
3. Opioid naïve or oral morphine equivalent use <60 mg/day.
4. Greater than grade 1 CIPN based on CTCAE.
5. >3/10 average CIPN-related neuropathic pain lasting ≥3 months beyond chemotherapy completion.
6. A cancer diagnosis.
7. Treatment with one of the following neurotoxic chemotherapies: platinums, taxanes, vinca alkaloids, bortezomib, or thalidomide.
Exclusion Criteria:
1. Other causes of peripheral neuropathy.
2. The following psychiatric illnesses: severe depression, suicidality, bipolar disease or psychotic disorder, alcohol or substance use disorder, DSM V criteria eating disorder.
3. The following medical illnesses: known or suspected mechanical gastrointestinal obstruction or any disease/conditions that affect bowel transit, suspected surgical abdomen, acute or severe asthma, COPD, acute respiratory depression, elevated serum CO2 and cor pulmonale, delirium tremens, convulsive disorders, severe CNS depression such as from cerebrospinal or intracranial pressure and head injury, diarrhea from pseudomembranous colitis, leptomeningeal disease.
4. Liver or renal dysfunction within the last 90 days as defined by MELD-Na score ≥17 and GFR ≤30 ml/min respectively.
5. QTC >499ms within last 90 days.
6. Current pregnancy or lactation.
7. Inability to take oral medications.
8. Positive CAGE and/or Opioid Risk Tool - Revised questionnaire
9. Known allergy or hypersensitivity to opioids, duloxetine, or any ingredient in their formulation.
10. Concomitant use of excluded medications: methadone, other antidepressants (including within 14 days of discontinuing monoamine oxidase inhibitors), thioridazine, potent CYP1A2 inhibitors (such as fluvoxamine and some quinolone antibiotics).
11. Uncontrolled narrow-angle glaucoma.
12. If women of child-bearing potential (i.e. Menstruation within <2 years) are unable or unwilling to use Health Canada approved highly effective methods of contraception (hormonal contraceptives, intrauterine device or system, vasectomy, tubal ligation, or double barrier method), or abstinence during the treatment period.
Note: Any use of prior co-analgesics will be continued (and must have been stable for more than 2 weeks), but the use of new co-analgesics or titration of current co-analgesics will not be permitted during the trial.