title: Low-dose vaporized cannabis significantly improves neuropathic pain.
abstract: 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. Mixed-effects regression models demonstrated an analgesic response to vaporized cannabis. There was no significant difference between the 2 active dose groups' results (P > .7). The number needed to treat (NNT) to achieve 30% pain reduction was 3.2 for placebo versus low-dose, 2.9 for placebo versus medium-dose, and 25 for medium- versus low-dose. As these NNTs are comparable to those of traditional neuropathic pain medications, cannabis has analgesic efficacy with the low dose being as effective a pain reliever as the medium dose. Psychoactive effects were minimal and well tolerated, and neuropsychological effects were of limited duration and readily reversible within 1 to 2 hours. Vaporized cannabis, even at low doses, may present an effective option for patients with treatment-resistant neuropathic pain.
  
  
  CONCLUSIONS
  The analgesia obtained from a low dose of delta-9-tetrahydrocannabinol (1.29%) in patients, most of whom were experiencing neuropathic pain despite conventional treatments, is a clinically significant outcome. In general, the effect sizes on cognitive testing were consistent with this minimal dose. As a result, one might not anticipate a significant impact on daily functioning.
authors.affiliation: VA Northern California Health Care System, and Department of Physical Medicine and Rehabilitation, University of California, Davis Medical Center, Sacramento, California 95817, USA. blwilsey@ucdavis.edu
authors.forename: Barth
authors.initials: B
authors.lastname: Wilsey
authors.forename: Thomas
authors.initials: T
authors.lastname: Marcotte
authors.forename: Reena
authors.initials: R
authors.lastname: Deutsch
authors.forename: Ben
authors.initials: B
authors.lastname: Gouaux
authors.forename: Staci
authors.initials: S
authors.lastname: Sakai
authors.forename: Haylee
authors.initials: H
authors.lastname: Donaghe
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000339:Affect / Q000187:drug effects; D002188:Cannabis / Q000009:adverse effects / Q000737:chemistry; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D013759:Dronabinol / Q000032:analysis; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000209:etiology / Q000523:psychology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000188:drug therapy* / Q000209:etiology / Q000523:psychology; D009483:Neuropsychological Tests; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D018579:Patient Selection; D008517:Phytotherapy / Q000379:methods*; D012959:Socioeconomic Factors; D016896:Treatment Outcome; D014835:Volatilization
chemical_list: D013759:Dronabinol