IACM-Bulletin of August 17, 2008

Science — Smoked cannabis effective against neuropathic pain of HIV patients

Researchers at the University of California in San Diego, USA, investigated the effects of smoked cannabis in HIV patients suffering from neuropathic pain. All patients experienced pain despite receiving pain medication. Of 34 subjects included, 28 completed the placebo controlled study. Participants received both cannabis cigarettes with a dronabinol content between 1 and 8 per cent four times daily for five days and placebo cigarettes. Both treatment phases where interrupted by two weeks of no medication. On the first day of each treatment phase the appropriate dose was determined by starting with a cannabis cigarette containing 4 per cent dronabinol and then gradually decreasing or increasing according to side effects and pain relief. The 34 patients continued to use their current pain medication during the whole study, 22 using opioids and 21 using anticonvulsants.

Pain relief was significantly greater by cannabis than by placebo according to the so-called Descriptor Differential Scale (DDS). During the cannabis phase 46 per cent of the 28 patients who completed the study gained a pain relief of more than 30 per cent, compared to 18 per cent during the placebo phase. During the cannabis treatment week most subjects needed cannabis with a THC content of 2 per cent (n = 9) or 4 per cent (n = 10), while during the placebo week most participants increased up to the maximum nominal THC dose of 8 per cent (n = 26). Side effects were usually mild to moderate, but two subjects experienced severe side effects. Authors concluded that "smoked cannabis was generally well tolerated and effective when added to concomitant analgesic therapy in patients with medically refractory pain due to HIV DSPN" [distal sensory predominant polyneuropathy].

(Source: Ellis RJ, Toperoff W, Vaida F, van den Brande G, Gonzales J, Gouaux B, Bentley H, Atkinson JH. Smoked medicinal cannabis for neuropathic pain in HIV: a randomized, crossover clinical trial. Neuropsychopharmacology. 2008 Aug 6. [Electronic publication ahead of print])

Germany — Health Ministry tightens requirements for medical cannabis exemptions

The Federal Institute for Pharmaceuticals and Medical Products (BfArM, Bundesinstitut für Arzneimittel und Medizinprodukte), an office of the federal health ministry, changed in July the rules for patients who plan to apply for an exemption of cannabis use for medical purposes. So far, one of the requirements for an exemption was the ineffectiveness of dronabinol (THC) or the refusal by the health insurance to pay for dronabinol treatment. Under the new guidelines, such refusal will no longer be accepted as a sufficient cause and only the ineffectiveness of dronabinol will be considered.

A 19 May 2005 ruling by the Federal Administrative Court based on which to date some 10 applications for medical cannabis use have been approved, explicitly states that the BfArM cannot claim that dronabinol is available as an "equivalent" drug. The ruling states: "The [BfArM's] reference to a drug, which is not readily available nor affordable for the normal citizen does not represent an alternative that would eliminate the general public interest in the medical use of cannabis." In a letter to the Federal Drug Commissioner, Sabine Baetzing, Dr. Franjo Grotenhermen, chairman of the German Association for Cannabis as Medicine, writes: "Given these conditions, would you please clarify whether the guidelines for an application for the medical use of cannabis still comply with the stipulations of the Federal Administrative Court."

(Source: Application guidelines for patients seeking an exemption (§ 3, 2 law on narcotics) for the purchase of cannabis extract for use in a medicinally supervised self-therapy.

BfArM, Update July 2008)

Science — Cannabinoids as effective as other medications against neuropathic pain in a prospective observational study

Science: Cannabinoids as effective as other medications against neuropathic pain in a prospective observational study

Scientists at the University of Calgary, Canada, compared the effects of different medications used in the treatment of neuropathic pain in an observational study with 182 patients. From July 2003 until December 2005 patients with neuropathic pain of different causes, taking no other medication than weak analgesics (non-steroidal anti-inflammatory drugs), and referred to the Neuromuscular Clinic were included into the study.

More than one third of patients was given gabapentin (37 per cent) as first medication. Other medications given first in more than 10 per cent of patients were pregabalin, topirimate and amitryptiline. Cannabinoids (nabilone and Sativex) were given to 5 per cent of patients as first line therapy. Authors stated that "reasons for selecting gabapentin were typically because of anticipation of minor side effects, familiarity with its use, and nearly universal coverage through third party insurance agencies". There were no serious adverse events for patients by any of the medications. Prevalence of intolerable side effects was similar among the different groups of medications. Mean pain relief three and six months after beginning of treatment was also similar among the different medications.

(Source: Toth C, Au S. A prospective identification of neuropathic pain in specific chronic polyneuropathy syndromes and response to pharmacological therapy. Pain. 2008 Aug 6. [Electronic publication ahead of print])

News in brief

France — Illegal cannabis market

The annual sales figure for cannabis in France is estimated by the French Monitoring Centre of Drugs and Drug Addiction to be between 746 and 832 million Euros (1.11-1.24 billion US dollars). Consumers' average annual expenditure on cannabis was estimated to be around 202 Euros in France, compared to estimates obtained for New Zealand and the Netherlands (124 Euros) and the United States (362 Euros). (Source: Legleye S, et al. Drug Alcohol Rev 2008;27(5):466-72.)

USA — California

The Fourth District Court of Appeal in San Diego upheld California's medical cannabis law, rejecting arguments by San Diego and San Bernardino counties that allowing patients to use the drug with their doctor's approval violates federal narcotics laws. (Source: San Francisco Chronicle of 1 August 2008)

Spain — Seminar

The second European Seminar on Neuroimaging and Addiction with the title "Brain effects of cannabis use in humans" will be held on 4 September in Barcelona, organized by the Section of Neuroimaging of the Association of European Psychiatrists (AEP) and other organizers. For more information please send an e-mail to: egelabert@imim.es. (Source: Personal communication by Estel Gelabert)

Science — Cannabis withdrawal

Inhibitors of endocannabinoid degradation were suggested as therapeutic drugs for the treatment of cannabis withdrawal. (Source: Clapper JR, et al. Neuropharmacology. 2008 Jul 19. [Electronic publication ahead of print])