Trial of Dronabinol and Vaporized Cannabis in Chronic Low Back Pain

This study will involve treating low back pain associated with nerve injury with oral delta-9-tetrahydrocannabinol (Δ9-THC) or whole plant cannabis for eight weeks. Research subjects will consume either oral Δ9-THC (dronabinol), vaporized 3.7% Δ9-THC/5.6% CBD, or placebo. An analysis will then be determined to assess the risk--benefit ratio of dronabinol and vaporized 3.7% Δ9-THC/5.6% CBD .

The present study is designed to assess whether treatment with vaporized cannabis or dronabinol (oral Δ9-THC) reduces spontaneous and evoked pain more than placebo, and whether there are any differences between the two active treatments in terms of interference with activities of daily living. This study also aims to examine the effects of vaporized whole plant cannabis and dronabinol on mood, neuropsychological function, and psychomimetic side-effects (high, stoned, etc.) compared to placebo and to each other. In addition, we plan to examine the acute effects (after receiving stable treatment for 4 weeks) of vaporized cannabis and dronabinol compared to placebo and each other on driving skills.

Eligibility Criteria:
Inclusion Criteria:

Age greater than 18. Presence of chronic low back pain (CLBP) defined as the response to two questions 1) How long has back pain been an ongoing problem for you? 2) How often has low back pain been an ongoing problem for you over the past 6 months? A response of greater than 3 months to question 1 and a response of "at least half the days in the past 6 months" to question 2 will define CLBP according to the NIH Task Force on Research Standards for Chronic Low Back Pain.

The numerical pain intensity must be greater than 3/10 each day during the one-week observation period.

To avoid confounding by concurrent medications, participants will have had a stable analgesic regimen that they will continue throughout the study To obviate residual neuropsychological effects from cannabis exposure, participants will be abstinent from this herbal medicine for 7 days prior to study entry.

Exclusion Criteria:

Presence of another painful condition of greater severity than the neuropathic pain condition which is being studied.

History of traumatic brain injury. Clinically significant or unstable medical condition. Individuals with significant cardiovascular, hepatic or renal disease, uncontrolled hypertension, and chronic pulmonary disease (eg, asthma, COPD), will be excluded. If warranted clinically, subjects will undergo laboratory evaluation (blood chemistry, electrocardiogram, urinalysis, toxicology screening for confirmation. Females of childbearing potential will undergo pregnancy testing.

A positive result on toxicity screening will exclude individuals from participation. A urine drug test that screens for 5 categories of drugs: marijuana (Δ9-THC), cocaine, amphetamines/methamphetamines, opiates, benzodiazepines and phencyclidine (PCP) will be employed. A positive result for opioids and/or THC will not be exclusionary if the patient is receiving a prescription for an opioid and/or THC.

Allergy to sesame oil, lactose, or gelatin Vascular disease, especially Raynauld's syndrome, systolic blood pressure \> 170 mm, diastolic blood pressure \> 100 mm Recent injuries to the upper extremity Cognitive impairment, such as Dementia or Alzheimer's Disease Substance Abuse History: The Substance Abuse Module of the Diagnostic Interview Schedule for the Diagnostic and Statistical Manual (DSM)-IV will be administered to exclude individuals with current substance use disorders.

Pregnancy as ascertained by a mandatory commercial pregnancy test Past history of suicide attempt. Cannabis can exacerbate pre-existing schizophrenia, and has been linked to an increase in the risk of suicide in such patients. In patients with bipolar disorder, cannabis use has been associated with worsening of manic and psychotic symptoms. Such findings suggest that cannabis is contraindicated in individuals with serious mental health issues, a line of reasoning that will be observed in the present study by excluding patients in the bipolar/schizoaffective/schizophrenic spectrum.

Suicidality. Exposure to cannabis does not lead to depression but it may be associated with suicidal thoughts and attempts. Therefore, the Beck Depression Inventory (BDI)-II will be used to measure suicidal ideation.