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IACM-Bulletin of 22 June 2008

Science: Medical use of cannabinoids does not cause an increase in serious adverse health effects

Researchers at McGill University Health Centre, the McGill University in Montreal and the University of British Columbia in Vancouver, Canada, said that as the use of cannabinoid medications increases, so do concerns about their potential to cause "adverse events." Dr. Mark Ware of the McGill University Health Centre said that their analysis reported about 31 separate clinical studies of cannabinoid medications conducted between 1966 and 2007. Adverse events were categorized as either serious or non-serious; with serious adverse events defined as those leading to death, hospitalization or disability.

"Overall, we found an 86 percent increase in the rate of non-serious adverse events among the patients treated with cannabinoids compared to the patients in the control groups," Ware said in a statement. "The majority of events were mild to moderate in severity." The majority of non-serious adverse events observed involved dizziness and drowsiness, the researchers said. The findings were published in the Canadian Medical Association Journal and are available online including a comment by Australian researchers.

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(Sources: UPI of 17 June 2008; Wang T, Collet JP, Shapiro S, Ware MA. Adverse effects of medical cannabinoids: a systematic review. CMAJ 2008;178(13):1669-78; Degenhardt L, Hall WD. The adverse effects of cannabinoids: implications for use of medical marijuana. CMAJ 2008;178(13):1685-6.)

Science/USA: Controversies on the consequences of the increase of cannabis potency in recent decades

According to a report released by the American White House the average THC (dronabinol) concentration of cannabis seized in the United States increased from about 4 per cent in 1983 to 9.6 per cent in 2007. "Marijuana potency has grown steeply over the past decade, with serious implications in particular for young people," John Walters, director of the White House Office of National Drug Control Policy, said. He cited the risk of psychological, cognitive and respiratory problems, and the potential for users to become dependent on drugs such as cocaine and heroin.

However, an increase of cannabis potency within the past 25 years of about two and a half refute claims of a dramatic increase in recent decades and confirm results by Australian researchers, who investigated the development of dronabinol concentrations of cannabis in several countries. The researchers at the Australian National Drug and Alcohol Research Center and the National Drug Research Institute also noted that the claims that increased strength of cannabis is driving the occurrence of mental health problems is not supported by studies. Due to the enormous variation between samples cannabis users may be exposed to a greater variation in the strength of the cannabis they use in a single year than that over years or decades.

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(Sources: Associated Press of 12 June 2008, UPI of 18 June 2008; McLaren J, Swift W, Dillon P, Allsop S. Cannabis potency and contamination: a review of the literature. Addiction 2008;103(7):1100-9.)

News in brief

USA: Cannabis use by teens
According to an analysis by researchers of the State University of New York state medical cannabis laws in twelve states have not increased teen cannabis use, despite fears that have been raised when such measures are considered. Teen cannabis use has consistently declined in states with medical cannabis laws, and generally more markedly than national averages. The report, based entirely on data from federal and state government-funded drug use surveys, is available at www.mpp.org/teens/. (Source: MPP of 16 June 2008)

USA: Deaths from medical drugs
An analysis of autopsies in 2007 from Florida found that the rate of deaths caused by prescription drugs was three times the rate of deaths caused by all illegalized drugs combined. According to a report by the New York Times these findings track with similar studies by the federal Drug Enforcement Administration, which has found that roughly seven million citizens of the United States are abusing prescription drugs. If accurate, that would be an increase of 80 per cent in six years and more than all citizens abusing cocaine, heroin, hallucinogens, Ecstasy or inhalants. (Source: New York Times of 14 June 2008)

Science: Cannabidiol
According to research from Japan cannabidiolic acid, the form in which cannabidiol (CBD) is present in the cannabis plant, is a selective cyclooxygenase-2 inhibitor (COX-2 inhibitor). Delta-9-tetrahydrocannabinolic acid (THCA) was much less potent. COX-2 inhibitors have an anti-inflammatory effect. Drugs such as aspirin (acetysalicylic acid) suppress the production of prostaglandins and thromboxanes due to its inactivation of the cyclooxygenase (COX) enzyme. However, besides COX-2 aspirin inhibits also COX-1 enzymes, which may result in side effects such as stomach bleeding. (Source: Takeda S, et al. Drug Metab Dispos, 2008 Jun 12. [Electronic publication ahead of print])

Science: Granulomas
According to research by Italian scientists cannabinoids, which activate the CB1 or the CB2 receptor inhibit the production of blood vessels in granulomas and thus reduce inflammation in conditions associated with granulomas. They are seen in diseases such as Crohn's disease, tuberculosis and sarcoidosis. (Source: De Filippis D, et al. Br J Pharmacol, 2008 Jun 16. [Electronic publication ahead of print])

Science: Lymphomas
According to researchers of the Karolinska Institute in Stockholm, Sweden, high CB1 and CB2 receptors levels are found in most non-Hodgkin lymphomas. Cannabinoids induced cell death in these cancer cells. Researchers concluded, that "our results suggest that therapies using cannabinoid receptor ligands will have efficiency in reducing tumor burden in malignant lymphoma overexpressing CB1 and CB2." (Source: Gustafsson K, et al. Int J Cancer, 2008 Jun 10. [Electronic publication ahead of print])

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