Trial of Dronabinol and Vaporized Cannabis in Neuropathic Low Back Pain

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.

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 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 BDI-II will be used to measure suicidal
ideation.