Effects of Vaporized Marijuana on Neuropathic Pain

We conducted a double-blind, placebo-controlled, crossover study evaluating the analgesic efficacy of vaporized cannabis in subjects, the majority of whom were experiencing neuropathic pain despite traditional treatment. Thirty-nine patients with central and peripheral neuropathic pain underwent a standardized procedure for inhaling medium-dose (3.53%), low-dose (1.29%), or placebo cannabis with the primary outcome being visual analog scale pain intensity. Psychoactive side effects and neuropsychological performance were also evaluated.

Inclusion criteria

• Age greater than 18 and less than 70
• Visual Analogue Scale (VAS pain intensity) greater than 3/10
• A negative urine drug screening test, i.e., no evidence of IV drug abuse
• Neuropathic pain due to reflex sympathetic dystrophy, peripheral neuropathy, post-herpetic neuralgia, post-stroke pain, multiple sclerosis or spinal cord injury

Exclusion criteria

• Presence of another painful condition of greater severity than the neuropathic pain condition which is being studied.
• Subjects with moderate-severe major depression, bipolar/mania, bipolar II/hypomania and schizophrenia or schizoaffective disorder.
• Unstable Type 1 or 2 diabetes defined as blood glucose more than 156 mg/dl
• History of traumatic brain injury
• Uncontrolled medical condition, including coronary artery disease, hypertension, cerebrovascular disease, asthma, tuberculosis (TB), chronic obstructive pulmonary disease (COPD), opportunistic infection, malignancy requiring active treatment, active substance abuse (alcohol or injection drugs).
• Current use of marijuana (e.g., within 30 days of randomization)
• Pregnancy as ascertained by a self-report and a mandatory commercial pregnancy test.