IACM-Bulletin of July 10, 2005

Science — Cannabis smoking does not cause cancer according to a case-control study

According to a case-control study by Dr. Donald Tashkin and his colleagues of the University of California in Los Angeles even heavy and longterm smoking of cannabis is not associated with lung cancer and other types of upper aerodigestive tract cancers. The results were presented on 26 June at the annual conference of the International Cannabinoid Research Society (ICRS).

The study included 1,209 residents of Los Angeles aged 18-59 with cancer (611 lung, 403 oral/pharyngeal, 90 laryngeal, and 108 esophageal). Interviewers collected lifetime histories of cannabis, tobacco, alcohol and other drug use, and data on other factors that may influence cancer risk, including diet, occupational exposures, and family history of cancer. Exposure to cannabis was measured in joint years (1 joint year = 365 joints). The cancer patients were compared to 1,040 cancer-free controls. Among the controls 46 per cent had never used cannabis, 31 per cent had used it for less than one joint year, 12 per cent for 10-30 joint years, 2 per cent for 30-60 joint years, and 3 per cent for more than 60 joint years.

Compared with subjects who had used less than one joint year, the risk for lung cancer was 0.78 for 1-10 joint years, 0.74 for 10-30 joint years, 0.85 for 30-60 joint years, and 0.81 for more than 60 joint years. A risk below 1.0 means that the risk for cannabis users was slightly lower than for non-users. Similar results were obtained for the other cancer sites. There was no dose-response relationship of cancer risk, which means that there was no increased risks for more intensive users. The data on tobacco use, as expected, revealed a very potent effect and a clear dose-response relationship.

(Source: Morgenstern H, et al. Marijuana use and cancers of the lung and upper aerodigestive tract: results of a case-control study. Presentation at the ICRS Conference on Cannabinoids, 24-27 June, Clearwater, USA)

Science — News at the 2005 ICRS Conference

This year's conference of the International Cannabinoid Research Society (ICRS) was held on 24-27 June in Clearwater, Florida. About 300 scientists attended the meeting. Some abstracts are presented in brief below.

(1) Neuropathic pain: Preliminary results of a randomized, placebo-controlled study involving 50 patients with HIV-related peripheral neuropathy who received either smoked cannabis or placebo-cannabis were presented. In the study conducted at the University of California cannabis was shown to provide pain relief comparable to Gabapentin, the most widely used treatment for a condition that afflicts some 30 per cent of patients with HIV. (Abstract by D. Abrams et al.)

(2) Schizophrenia: Results of a four-week double-blind clinical trial on cannabidiol and amisulpride in acute schizophrenia were presented by researchers of the University of Cologne. Cannabidiol significantly reduced psychopathological symptoms of acute psychosis after both, week two and four, when compared to the initial status. There was no significant difference in efficacy between cannabidiol and amisulpride. However, cannabidiol caused significantly less side effects than the other drug. (Abstract by M. Leweke et al.)

(3) Withdrawal: Abrupt interruption of one year of treatment with the cannabis extract Sativex was not associated with a withdrawal syndrome or serious withdrawal symptoms in 25 patients with multiple sclerosis. About half of the patients experienced symptoms previously reported in connection with withdrawal from regular use of recreational cannabis. (Abstract by E. Russo & P. Robson)

(4) CB2 receptor in the brain: Research in mice was presented that demonstrated the presence of the CB2 receptor in the brain. Their number was enhanced by chronic mild stress (CMS). These results suggest that CB2 receptors are expressed in the mammalian brain and may play a role in depression. (Abstract by E. Onaivi et al.)

(5) Amyotrophic lateral sclerosis (ALS): A synthetic cannabinoid (AM1241) that selectively binds to the CB2 receptor was shown to slow disease progression in a mouse model of ALS. Loss of motor function was delayed by 12.5 days in male mice and by 3 days in female mice. (Abstract by M. Abood et al.)

(Source: Reader of the 2005 ICRS meeting, www.cannabinoidsociety.org.)

USA — Rhode Island will likely legalize the medical use of cannabis despite a veto by the governour

The state senate of Rhode Island voted on 6 July to override the veto of governour Don Carcieri against a bill that will allow the medical use of cannabis. If the House of Representatives overrides the veto as well, Rhode Island would become the 11th state to permit medical cannabis use.

Carcieri vetoed the bill on 5 July after the House of Representatives had approved the bill by votes of 52-10 and the Senate by 34-2. An override requires votes from three-fifths of the lawmakers in both chambers. The Senate approved the override 28-6.

The law would allow those with a "debilitating medical condition," including cancer, glaucoma and AIDS, to receive a signed statement from their doctor stating they would benefit from cannabis. Patients and their caregivers would be entered into a registry kept by the State Department of Health. They would be permitted to have up to 12 cannabis plants or 2 1/2 ounces of usable cannabis.

(Sources: Associated Press of 30 June 2005, New York Times of 29 June 2005)

News in brief

Science Canada — Cannabis in chronic pain

The Vancouver Island Compassion Club (VICC) announced that Health Canada has granted approval "for a study looking at the effects of smoked cannabis and chronic pain." The study is being funded with a 50,000 Canadian Dollars grant from the Marijuana Policy Project and conducted by Philipe Lucas (VICC), Dr. Shannon Hamersley, and Rick Doblin, director of the Multidsiciplinary Association of Psychedelic Studies. The group plans to provide 15 participants with cannabis of varying strengths. (Source: Victoria News of 29 June 2005)

USA — California

Concerned that state workers might be charged with abetting federal crimes, California health officials announced on 8 July that they would no longer issue identification cards to medical cannabis patients. Sandra Shewry, the state health director, said the decision came in response to a United States Supreme Court ruling last month. In a 6-to-3 vote, the court upheld the power of the federal authorities to prosecute the possession and use of cannabis for medical purposes, even in states like California that allow such use under state law. (Source: New York Times of 9 July 2005)

Science — Stress-induced analgesia

Acute stress suppresses pain. This stress-induced analgesia is partly mediated by endogenous opioids. New research shows that it is also partly mediated by endogenous cannabinoids (endocannabinoids). This effect is based on the coordinated release of 2-AG (2-arachidonoylglycerol) and anandamide in the periaqueductal grey matter. (Source: Hohmann AG, et al. Nature 2005;435(7045):1108-12)

Science — Sublingual bioavailability of THC

Novel cyclodextrin-containing sublingual formulations of cannabinoids were developed by Finish researchers. By adding cyclodextrin to THC or CBD their solubility in water was considerably increased. Sublingual administration of a THC/cyclodextrin complex substantially increased the bioavailability of THC in rabbits. (Source: Mannila J, et al. Eur J Pharm Sci 2005 Jun 12; [Electronic publication ahead of print] )