IACM-Bulletin of March 6, 2005

Science — Cannabinoids reduce the progression of Alzheimer's disease in animals

Research by scientists of Madrid's Complutense University and the Cajal Institute published in the Journal of Neuroscience has demonstrated that cannabinoids can reduce pathological processes associated with Alzheimer's disease. Researchers hope that cannabinoids may be used to develop new drug therapies against the disease.

They first compared the brain tissue of patients who died from Alzheimer's disease with that of healthy people who had died at a similar age. The researchers found a dramatically reduced functioning of cannabinoid receptors in diseased brain tissue and markers of microglia activation. Microglia activate the brain's immune response and are found near the plaque deposits associated with Alzheimer's disease. When active, microglia cause inflammation. Nerve cells with cannabinoid-1 receptors (CB1), present in high numbers in control subjects, were greatly reduced in areas of microglial activation.

In a second step rats were injected with amyloid-beta peptide. This protein plays an important role in Alzheimer's disease, since increased brain levels of amyloid-beta are supposed to result in aggregation of this protein to form plaques. Animals who also received different cannabinoids performed better in tests of their mental functioning. Analyses showed that cannabinoids had prevented microglial activation and thus had reduced inflammation. These effects were also mediated by cannabinoids that only bind to CB2 receptors.

Researchers concluded: "Our results indicate that cannabinoid receptors are important in the pathology of AD and that cannabinoids succeed in preventing the neurodegenerative process occurring in the disease."

British researchers, who published their work in the journal Sub-Cellular Biochemistry, found that phosphorylation of amyloid-beta increased the neurotoxicity of this protein. And they demonstrated that cannabinoids prevented these damaging effects of phosphorylated amyloid-beta on nerve cells.

(Sources: Ramirez BG, et al. Prevention of Alzheimer's disease pathology by cannabinoids: neuroprotection mediated by blockade of microglial activation. J Neurosci 2005;25(8):1904-13; Milton NG. Phosphorylated amyloid-beta: the toxic intermediate in alzheimer's disease neurodegeneration. Subcell Biochem 2005;38:381-402; BBC News of 22 February 2005)

UK/USA — GW Pharmaceuticals accelerates plans to introduce Sativex in the USA

The British company GW Pharmaceuticals said on 28 February it was accelerating plans to introduce its cannabis-based medicines into the United States. GW said it had engaged the U.S.-based Apjohn Group, a 10-member group of former major U.S. pharmaceutical company executives with extensive experience in clinical development, regulatory affairs and public policy.

GW's Sativex has won qualified approval in Canada for the treatment of neuropathic pain in multiple sclerosis in December 2004, but approval in Great Britain for the treatment of spasticity in multiple sclerosis has been repeatedly delayed. Sativex is an under-the-tongue cannabis spray containing equal amounts of THC and CBD.

(Source: Reuters of 28 February 2005)

News in brief

Canada — Tax relief for medical cannabis

Canadians will get tax relief to buy medical cannabis under the federal budget proposed by finance minister Ralph Goodale. Marijuana bought for medical purposes from Health Canada or a designated grower will be eligible for tax relief after the annual medical expenses exceed 3 per cent of net income or 1,844 Canadian dollars. (Source: Toronto Star of 24 February 2005)

Austria — New research centre

A new research centre for plant derived drugs will be founded in Innsbruck. The main focuses of Bionorica Research will be the investigation of plant derived airway therapeutics and the investigation of cannabis products for medical purposes. A subsidiary company of Bionorica in Germany, Delta 9 Pharma, already produces the cannabis compound dronabinol (THC) for medical uses. (Source: Der Standard of 28 February 2005)

USA — New Mexico

The state Senate of New Mexico has approved three separate bills that would allow the medical use of cannabis, but it is unclear whether the House of Representatives will support them. Under one of the measures, the cannabis would be grown at licensed, secure facilities and then distributed to patients who were registered to possess and smoke it. An alternative bill requires the medical marijuana to be manufactured by a drug company. The third bill the Senate endorsed would allow the use of marijuana only topically, such as in an ointment. (Source: Associated Press of 2 March 2005)

Australia — Australian Capital Territory

Changes of the drug laws of the Australian Capital Territory (ACT), one of the Australian states, came into effect on 6 March. They reduce the number of cannabis plants that can be cultivated without being charged with a criminal offence from five to two plants. The criminal law allows a person to posses up to 25 grams of dried cannabis for personal use. (Source: Government of ACT of 1 March 2005, http://www.cmd.act.gov.au)