Opioid and Cannabinoid Pharmacokinetic Interactions
Condition: Pain
Intervention: Cannabis
Phase: Phase 1
Study type: Interventional
Primary purpose: Treatment
Intervention model: Single Group Assignment
Masking: None (Open Label)
Enrollment: 24.0
Sex: All
Minimum age: 18 Years
Healthy volunteers: No
Keywords: Cannabis; Morphine; Oxycodone; Marijuana; chronic pain

Summary:

      We are conducting a study to assess whether smoking marijuana affects the safety of
      prescribed opioids in patients treated for chronic pain. This study will assess whether
      smoking cannabis affects the absorption, distribution, metabolism and excretion of widely
      used opioid analgesics. We propose to do this by investigating the effects of smoked cannabis
      in subjects prescribed morphine or oxycodone for chronic pain. We will also assess the
      clinical safety of cannabinoids and these opioids by monitoring the short-term side effects
      associated with combined therapy.
    

Eligibility criteria:

        Inclusion Criteria:

          1. Ongoing analgesic therapy with either oxycodone hydrochloride (OxyContin) or morphine
             sulfate (MS Contin) every 12 hours for chronic pain.

          2. Eligible subjects will be ≥ 18 years of age with a diagnosis of chronic pain and an
             estimated survival of greater than six months.

          3. Subjects must be on a stable dose of opioid medication for at least 2 weeks before
             enrollment.

          4. Current other analgesic medications will be maintained during the study. The subject
             must have been on a stable medication regimen for at least 2 weeks.

          5. The following laboratory parameters documented within 45 days prior to study entry:

               -  Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 5 X upper
                  limit of normal (ULN)

               -  Total bilirubin ≤ 2 X ULN

               -  Creatinine ≤ 2.0 mg/dL (177 µmol/L)

          6. All men and women in this study must agree to use adequate birth control during this
             study. Acceptable barrier birth control methods are a male condom, female condom,
             diaphragm, or intra-uterine (IUD).

          7. All women of reproductive potential (who have not reached menopause or undergone
             hysterectomy, oophorectomy, or tubal ligation) must have a negative urine b-HCG
             pregnancy test performed before initiating the protocol-specified medication.

          8. Prior history of use of marijuana. Subjects must have smoked marijuana on at least 6
             occasions in their lifetime prior to enrollment.

          9. Able to understand and follow the instructions of the investigator, including
             completing the pain intensity rating scales.

         10. Karnofsky Performance Score >60.

         11. Able and willing to provide informed consent.

        Exclusion Criteria:

          1. Severe coronary artery disease, uncontrolled hypertension, cardiac ventricular
             conduction abnormalities, or orthostatic mean blood pressure drop greater than 24
             mmHg, severe chronic obstructive pulmonary disease.

          2. History of renal or hepatic failure.

          3. Evidence of hepatic, hematological or renal dysfunction based on judgment of
             physician.

          4. Active substance abuse (e.g., alcohol or injection drugs).

          5. Use of smoked marijuana within 30 days of enrollment verified with a urine THC level.

          6. Neurologic dysfunction or psychiatric disorder severe enough to interfere with
             assessment of pain or sensory systems.

          7. Current use of smoked tobacco products or a confirmed cotinine level.

          8. Women who are pregnant or breast-feeding may not take part in this study.

          9. Unable to read or speak English.