Dronabinol Opioid Sparing Evaluation (DOSE) Trial

Inclusion Criteria: 1. Ability to read, speak, and understand English; 2. Provision of signed and dated informed consent form; 3. Stated willingness to comply with all study procedures and availability for the duration of the study; 4. Male, Female, or Transgender aged \> 18; 5. In fair and stable general health as evidenced by medical history and physical examination, and confirmed by prescriber; 6. Participants who have been diagnosed with a pain condition that has not adequately responded to other treatments, in the judgement of the provider; 7. Participants who are currently taking a stabilized dose of opioid analgesics, and who have been taking opioid analgesics for at least 3-months, and who report a score of \> 3 on the Brief Pain Inventory 0-10 severity index.; 8. Ability to take medications as prescribed and willingness to adhere to the study-drug regimen; 9. For females of reproductive potential: use of highly effective contraception for at least 1 month prior to enrollment and agreement to use such a method during study participation; 10. Agreement to abstain from the use of cannabis or other cannabinoid compounds, other than the study-drug Dronabinol, throughout study duration; Exclusion Criteria: 1. Current substance abuse by self-report; 2. Current use of cannabis or other cannabinoid compounds; 3. Significant baseline nausea, vomiting, sedation, or other symptoms reported by physician and or patient that may compromise the collection of study-related data; 4. A history of seizures, head trauma, and or mental illness ; 5. Pregnancy or lactation; 6. Known allergic reactions to components of Dronabinol; 7. Taking any of the following drugs: Strong CYP2C9 Inhibitor (e.g., amiodarone, fluconazole) Strong CYP3A4 Inhibitor (e.g., ketoconazole, itraconazole, clarithromycin, ritonavir, erythromycin) Potent CYP2C9 or CYP3A4 inducers (e.g., rifampicin) Drugs that are highly protein-bound (e.g., warfarin, cyclosporine, amphotericin B)