IACM-Bulletin of September 14, 2008

Science — Cannabis extract effective against neuropathic pain of MS patients in long-term study

According to a press release by the British company GW Pharmaceuticals, Sativex was effective in 42 patients with multiple sclerosis and central neuropathic pain who had previously been in a phase III study and who continued to take Sativex for 12 weeks. They were then randomised to a treatment with Sativex or placebo for a further 4 weeks in a double-blinded manner. Sativex is a cannabis extract containing equal amounts of dronabinol (THC) and cannabidiol (CBD), which is administered as a spray into the mouth. During this four-week period, patients were not permitted to adjust their dose.

In the patients who were randomised to cannabis, pain scores remained stable. In the patients randomised to placebo, pain and sleep scores deteriorated. There was a significant difference between the pain scores in the Sativex and the placebo group, and sleep quality was also significantly better with the cannabis extract. During this four-week period, there were 2 patients with adverse events on Sativex, and 5 on placebo. One patient on placebo withdrew from the study. There was no evidence of any withdrawal syndrome. Dr. Stephen Wright of GW Pharmaceuticals said: "This is the first placebo-controlled study showing that Sativex provides long term efficacy for MS patients with neuropathic pain and supplements previously published open-label studies."

More at: http://www.gwpharm.com/

(Source: Press release by GW Pharmaceuticals of 8 September 2008)

News in brief

UK — Cannabis potency

According to official data the potency of seized cannabis dropped about 25 per cent from an average THC concentration of 12.7 per cent to 9.5 per cent from 2004 to 2007. In 2004 cannabis was classified from class B to the less serious class C of the British narcotics law. Now the government plans a reclassification of cannabis to class B, refering to the increase of cannabis potency in recent years and decades. The newspaper The Guardian wrote that this casts "doubt on one of the government's key arguments for reclassifying the drug again from class C to class B." (Source: The Guardian of 28 August 2008)

Science — New cannabis constituents

Researchers from the National Center for Natural Products Research of the University of Mississippi, USA, isolated six new non-cannabinoid constituents from a high potency cannabis variety. In addition, two known substances (chrysoeriol and 6-prenylapigenin) were detected for the first time in cannabis. Some of these compounds displayed weak to strong activities against bacteria, leishmania, and pathogens causing malaria. (Source: Radwan MM et al. Phytochemistry. 2008 Sep 4. [Electronic publication ahead of print])

Science — Schizophrenia and hyperactivity

Researchers at the University of Nottingham, UK, investigated the effects of cannabis use on mental health functioning in three groups of young people; 36 non-psychotic siblings of adolescents with schizophrenia (genetic high risk group), 25 adolescents with attention deficit hyperactivity disorder (ADHD) and 72 healthy controls. In young people at genetic high risk for schizophrenia cannabis use was associated with mental health disturbance. In adolescents with ADHD, cannabis use was associated with a trend to decreased disorganization and decreased hyperactivity/inattention. In this group cannabis might have a positive effect. (Source: Hollis C, et al. Schizophr Res. 2008 Sep 1. [Electronic publication ahead of print])

Science — Neurotoxicity

Increased levels of endocannabinoids reduced the toxicity of a substance (diisopropylfluorophosphate, DFP) that causes an accumulation of the neurotransmitter acetylcholine and excessive stimulation of cholinergic receptors. Researchers concluded that these "results suggest that enhancing endocannabinoid signalling can attenuate the acute toxicity of DFP and provide rationale for further investigations on the role of endocannabinoids in cholinergic toxicity." (Source: Nallapaneni A, et al. Neurotoxicology. 2008 Aug 13. [Electronic publication ahead of print])

Science — Psychosis

Spanish researches investigated the effects of cannabis use on the age at onset of psychosis in 131 patients with a first psychotic episode admitted to a hospital. In cannabis users psychosis set in significantly earlier than in non-users and this effect was dose-dependant, and not explained by the use of other drugs. (Source: González-Pinto A, et al. J Clin Psychiatry. 2008 Jul 29. [Electronic publication ahead of print])