IACM-Bulletin of October 2, 2005

Science — Cannabis reduces neuropathic pain due to multiple sclerosis in clinical study

British researchers of the Walton Centre for Neurology and Neurosurgery in Liverpool demonstrated that the cannabis extract Sativex of GW Pharmaceuticals is effective in reducing central neuropathic pain and sleep disturbance in people with multiple sclerosis (MS). "Central neuropathic pain occurs frequently in people with MS. It can be tremendously debilitating and unresponsive to existing therapies," Dr Carolyn Young, principal investigator of the study, said.

The 5 week placebo-controlled study was conducted in 66 patients with MS who suffered from chronic neuropathic pain. 64 patients completed the trial, of whom 32 received the cannabis extract and 32 the placebo. Sativex contains equal amounts of THC and cannabidiol (CBD) and is administered as a spray under the tongue. The mean maximum daily THC dose was 25 mg (range: 5-65 mg). Pain and sleep disturbance were recorded daily on an 11-point numerical rating scale. Cannabis caused a significant mean pain reduction of 2.7 points (baseline: 6.5) compared with 1.4 points (baseline: 6.4) following placebo. Sleep was significantly improved by 2.5 points with cannabis compared to 0.8 points with placebo. The cannabis extract was generally well tolerated, although more patients on cannabis than placebo reported dizziness, dry mouth, and somnolence.

Based on these study results, which were published now in the journal Neurology, Sativex was approved as a prescription medicine in Canada for the symptomatic relief of neuropathic pain in adults with MS and is available in pharmacies since 20 June 2005.

(Sources: Rog DJ, Nurmikko TJ, Friede T, Young CA. Randomized, controlled trial of cannabis-based medicine in central pain in multiple sclerosis. Neurology 2005;65(6):812-9; press release by GW Pharmaceuticals of 27 September 2005)

Science — Survey on medical use of cannabis in sickle cell disease

An anonymous questionnaire survey was conducted at the Central Middlesex Hospital in London among adults suffering from sickle cell disease (SCD). 86 subjects aged 23 to 39 years participated in the study. 31 had used cannabis in the previous 12 months to relieve symptoms associated with SCD. The main route in all but two patients was by smoking. The main reasons for use were to reduce pain in 52 per cent, and to induce relaxation or relieve anxiety and depression in 39 per cent.

SCD is a blood condition caused by a cell mutation, which is seen most commonly in people from Africa and India. Sickle cell syndromes also occur in people of Mediterranean and Middle Eastern background. This mutation causes a change in haemoglobin, the oxygen-transport protein in red blood cells. Pain is one of the predominant symptoms in SCD. It can be severe enough to require opioid analgesics for relief, can recur acutely at unpredicted intervals, is associated with inflammation and can become chronic.

(Source: Howard J, Anie KA, Holdcroft A, Korn S, Davies SC. Cannabis use in sickle cell disease: a questionnaire study. Br J Haematol 2005;131(1):123-8.)

News in brief

USA — Survey in Wisconsin

A state-wide poll released on 14 September shows that Wisconsin residents support the legalization of cannabis for medical use. The telephone survey of 600 randomly selected Wisconsin residents was conducted in July 2005, by Chamberlain Research Consultants as part of Chamberlain's quarterly Wisconsin Trends poll. Polling on the medical cannabis question was commissioned by the Marijuana Policy Project (MPP). 75.7 per cent said they would support legislation to permit patients with cancer, multiple sclerosis, or other serious illnesses to use marijuana for medical purposes with their physicians' approval. Republicans supported the proposal by a margin of 68 per cent, while among Democrats the margin was 83.9 per cent. (Sources: Press release of MPP of 14 September 2005, Oshkosh Northwestern of 28 September 2005)

Science — Physicians' attitudes

960 US family physicians, general internists, gynaecologists, psychiatrists, and addiction specialists offered opinions about the legal prescription of cannabis for medical purposes. 36 per cent believed prescribed marijuana should be legal and 26 per cent were neutral to the proposition. Internal medicine and gynaecology specialization was associated with support for the medical use of cannabis, whereas psychiatrists and addiction specialists opposed it more often. The authors write that "physicians are, in general, less supportive than the general American public regarding the use of medical marijuana." However, the study data are more than four years old. (Sources: Charuvastra A, et al. J Addict Dis 2005;24(3):87-93; Reuters of 23 April 2001)

Science — Cannabis and driving

In a study by researchers of the University of Maryland the use of cannabis was not associated with the risk to cause a traffic accident. 6,581 drivers who were hospitalized at a shock trauma center in the years 1997 through 2001 form the basis of this analysis. Results on the presence of alcohol and illegal drugs obtained for patient care were linked to police crash reports. Crash culpability was strongly associated with alcohol use. In contrast, this study did not find an association between crash culpability and cannabis use. Since only urine tests on cannabinoids were performed it is not known, whether drivers were actually under the influence of cannabis. (Source: Soderstrom CA, et al. Annu Proc Assoc Adv Automot Med 2005;49:315-30.)

Science — Endocannabinoids and obesity

Research at the Charité Hospital in Berlin showed that the concentrations of circulating endocannabinoids (anandamide and 2-AG) were significantly elevated in obese compared to lean women. On the other hand, expression of the CB1 receptor and of the enzyme fatty acid amide hydrolase (FAAH), which is mainly responsible for the degradation of anandamide, were significantly increased in fat tissue of obese subjects compared to controls. Researchers note that their "findings support the presence of a peripheral endocannabinoid system that is upregulated in human obesity." (Source: Engeli S, et al. Diabetes 2005;54(10):2838-43.)

Science — Body mass index and cannabis

US researchers investigated the correlation between cannabis use and body mass index (BMI). The BMI is a measure for the relationship between weight and height. A high BMI is found in obese subjects. The study with 297 women showed that despite cannabis is known to increase appetite, cannabis use in the past year was more common in subjects with low BMI, that is slim women. (Source: Warren M, et al. J Addict Dis 2005;24(3):95-100.)