IACM-Bulletin of November 25, 2007

Science — Cannabis improved neuropathic pain in clinical study

According to a clinical study with 125 patients conducted at several centres under the guidance of professor Turo Nurmikko of the Walton Centre for Neurology and Neurosurgery, Liverpool, the cannabis extract Sativex significantly reduced neuropathic pain. In this 5-week placebo-controlled study 63 patients received Sativex and 62 received placebo. Patients remained on their existing stable analgesia. Sixty-nine percent of patients were taking opioid analgesics.

The mean reduction in pain intensity on a 0-10 scale was significantly greater in patients receiving Sativex than placebo (mean reduction -1.48 points vs. -0.52 points). Significant improvements were seen in other parameters including sleep, pain disability index and patient's global impression on change. Side effects were usually mild or moderate. Of all participants, 18 per cent on Sativex and 3 per cent on placebo withdrew during the study. An open-label extension study showed that the initial pain relief was maintained without dose escalation for 52 weeks.

(Sources: Nurmikko TJ, Serpell MG, Hoggart B, Toomey PJ, Morlion BJ, Haines D. Sativex successfully treats neuropathic pain characterised by allodynia: A randomised, double-blind, placebo-controlled clinical trial. Pain 2007 Nov 6; [Electronic publication ahead of print]; press release by GW Pharmaceuticals of 12 November 2007)

Science — Cannabidiol may be helpful in reducing the aggressiveness of breast cancer cells

In a mouse model of metastatic breast cancer the natural non-psychotropic cannabinoid cannabidiol (CBD) reduced the aggressiveness of breast cancer cells. CBD inhibited a protein called Id-1. Id proteins play an important role in tumour cell biology. The researchers of the California Pacific Medical Center Research Institute concluded that "CBD represents the first nontoxic exogenous agent that can significantly decrease Id-1 expression in metastatic breast cancer cells leading to the down-regulation of tumor aggressiveness."

The authors stressed that they were not suggesting patients smoke cannabis. They added that it would be highly unlikely that effective concentrations of CBD could be reached by smoking cannabis. Lead researcher Dr. Sean McAllister said: "Right now we have a limited range of options in treating aggressive forms of cancer. Those treatments, such as chemotherapy, can be effective but they can also be extremely toxic and difficult for patients. This compound offers the hope of a non-toxic therapy that could achieve the same results without any of the painful side effects."

(Sources: BBC News of 19 November 2007; McAllister SD, Christian RT, Horowitz MP, Garcia A, Desprez PY. Cannabidiol as a novel inhibitor of Id-1 gene expression in aggressive breast cancer cells. Mol Cancer Ther 2007;6(11):2921-7.)

News in brief

USA — Cannabis production

According to a report by the Justice Department the cannabis plant eradication program (called "Campaign Against Marijuana Planting") has driven cannabis producers to indoor sites. The report notes that one side effect of shifting to indoor sites is that "the groups will produce higher-potency marijuana year-round, allowing for exponential increase in profits derived." The report also notes that the eradication program had not reduced availability of cannabis. It says that the US cannabis market is "saturated". The report is available for download at: http://www.usdoj.gov/ndic/pubs25/25921/25921p.pdf (Source: National Drug Threat Assessment 2008)

Science — Migraine

Italian researchers demonstrated that the endocannabinoid system is impaired in patients with migraine and headaches caused from medication-overuse. Compared to 20 healthy subjects the concentrations of the endocannabinoids 2-AG and anandamide were lower in the platelets of 20 patients with migraine and of 20 patients with medication-overuse headaches. Serotonin levels were also strongly reduced in the two patient groups. (Source: Rossi C, et al. Eur J Clin Pharmacol 2007 Nov 15; [Electronic publication ahead of print])

Science — Nausea

In an animal model of anticipated nausea with rats cannabidiol (CBD) and an inhibitor of endocannabinoid degradation (URB597) was effective in reducing nausea. Anticipatory nausea experienced by chemotherapy patients does not respond well to current anti-nausea treatments. This form of nausea is caused by stimuli associated with previous nausea (e.g. odours of the hospital room) before receiving the actual chemotherapy. (Source: Rock EM, et al. Psychopharmacology (Berl) 2007 Nov 9; [Electronic publication ahead of print])

Science — Liver cirrhosis

In an animal study with rats with liver cirrhosis activation of the CB2 receptor with a selective CB2 receptor agonist for nine days significantly reduced signs of fibrosis including reduction of inflammation and improvement of arterial blood pressure. (Source: Munoz-Luque J, et al. J Pharmacol Exp Ther 2007 Nov 20; [Electronic publication ahead of print])

Science — Cannabidiol

In animal experiments with mice it was shown that high doses of CBD potentiated certain pharmacological effects of low doses of THC, such as hypoactivity and hypothermia. (Source: Hayakawa K, et al. Brain Res 2007 Oct 12; [Electronic publication ahead of print])

Science — Menstrual cycle

Scientists from North Carolina investigated the influence of several factors on the follicular phase of the menstrual cycle. The follicular phase is the phase until ovulation (first half of the menstrual cycle). Occasional cannabis users (up to three times in the last 3 months) had a longer follicular phase than nonusers (3.5 days). The follicular phase in frequent users (more than three times) was almost 2 days longer than that of nonusers. (Source: Jukic AM, et al. J Womens Health (Larchmt) 2007;16(9):1340-1347.)