sábado, 27 de noviembre de 2010

Cannabis

Cannabis fumada para el dolor neuropático crónico: un ensayo controlado aleatorizado
Smoked cannabis for chronic neuropathic pain: a randomized controlled trial.
Ware MA, Wang T, Shapiro S, Robinson A, Ducruet T, Huynh T, Gamsa A, Bennett GJ, Collet JP.
Department of Anesthesia, McGill University, Montréal, Que.
CMAJ. 2010 Oct 5;182(14):E694-701. Epub 2010 Aug 30.

Abstract
BACKGROUND: Chronic neuropathic pain affects 1%-2% of the adult population and is often refractory to standard pharmacologic treatment. Patients with chronic pain have reported using smoked cannabis to relieve pain, improve sleep and improve mood. METHODS: Adults with post-traumatic or postsurgical neuropathic pain were randomly assigned to receive cannabis at four potencies (0%, 2.5%, 6% and 9.4% tetrahydrocannabinol) over four 14-day periods in a crossover trial. Participants inhaled a single 25-mg dose through a pipe three times daily for the first five days in each cycle, followed by a nine-day washout period. Daily average pain intensity was measured using an 11-point numeric rating scale. We recorded effects on mood, sleep and quality of life, as well as adverse events. RESULTS: We recruited 23 participants (mean age 45.4 [standard deviation 12.3] years, 12 women [52%]), of whom 21 completed the trial. The average daily pain intensity, measured on the 11-point numeric rating scale, was lower on the prespecified primary contrast of 9.4% v. 0% tetrahydrocannabinol (5.4 v. 6.1, respectively; difference = 0.7, 95% confidence interval [CI] 0.02-1.4). Preparations with intermediate potency yielded intermediate but nonsignificant degrees of relief. Participants receiving 9.4% tetrahydrocannabinol reported improved ability to fall asleep (easier, p = 0.001; faster, p < 0.001; more drowsy, p = 0.003) and improved quality of sleep (less wakefulness, p = 0.01) relative to 0% tetrahydrocannabinol. We found no differences in mood or quality of life. The most common drug-related adverse events during the period when participants received 9.4% tetrahydrocannabinol were headache, dry eyes, burning sensation in areas of neuropathic pain, dizziness, numbness and cough. CONCLUSION: A single inhalation of 25 mg of 9.4% tetrahydrocannabinol herbal cannabis three times daily for five days reduced the intensity of pain, improved sleep and was well tolerated. Further long-term safety and efficacy studies are indicated. (International Standard Randomised Controlled Trial Register no. ISRCTN68314063).

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El sistema endocannabinoide y el dolor
The endocannabinoid system and pain.
Guindon J, Hohmann AG.
Neuroscience and Behavior Program, Department of Psychology, University of Georgia, Athens, GA 30602-3013, USA.
CNS Neurol Disord Drug Targets. 2009 Dec;8(6):403-21.

Abstract
The therapeutic potential of cannabinoids has been the topic of extensive investigation following the discovery of cannabinoid receptors and their endogenous ligands. Cannabinoid receptors and their endogenous ligands are present at supraspinal, spinal and peripheral levels. Cannabinoids suppress behavioral responses to noxious stimulation and suppress nociceptive processing through activation of cannabinoid CB(1) and CB(2) receptor subtypes. Endocannabinoids, the brain's own cannabis-like substances, share the same molecular target as Delta(9)-tetrahydrocannabinol, the main psychoactive component in cannabis. Endocannabinoids serve as synaptic circuit breakers and regulate multiple physiological and pathological conditions, e.g. regulation of food intake, immunomodulation, inflammation, analgesia, cancer, addictive behavior, epilepsy and others. This review will focus on uncovering the roles of anandamide and 2-arachidonoylglycerol, the two best characterized endocannabinoids identified to date, in controlling nociceptive responding. The roles of anandamide and 2-arachidonoylglycerol, released under physiological conditions, in modulating nociceptive responding at different levels of the neuraxis will be emphasized in this review. Effects of modulation of endocannabinoid levels through inhibition of endocannabinoid hydrolysis and uptake is also compared with effects of exogenous administration of synthetic endocannabinoids in acute, inflammatory and neuropathic pain models. Finally, the therapeutic potential of the endocannabinoid signaling system is discussed in the context of identifying novel pharmacotherapies for the treatment of pain.

Novedades sobre las potencialidades terapéuticas del Cannabis y el sistema cannabinoide 
Marta Duran, Joan-Ramon Laporte y Dolors Capellà
Fundació Institut Català de Farmacologia. Hospitals Vall d'Hebron.
Universitat Autònoma de Barcelona. Barcelona. España.
Med Clin (Barc) 2004;122(10):390-8

Durante la última década una rica investigación básica ha permitido caracterizar el sistema cannabinoide. Comienzan a acumularse pruebas de que los cannabinoides podrían ser eficaces en el tratamiento de las náuseas y vómitos por quimioterápicos antineoplásicos, el dolor, la espasticidad y otros síntomas de la esclerosis múltiple y algunas alteraciones del movimiento. Hay que esperar la publicación de los resultados de los ensayos clínicos en curso con extractos de Cannabis por vía oral y sublingual para definir de manera precisa su lugar en terapéutica en estas y otras indicaciones. Actualmente se están desarrollando nuevas vías de administración como la rectal, sublingual o transdérmica para evitar los efectos perjudiciales del humo del
Cannabis fumado. Aunque el futuro inmediato parece basarse en medicamentos derivados directamente del Cannabis, la investigación actual tiende a desarrollar por un lado nuevos fármacos que actúen potenciando o inhibiendo los efectos de los cannabinoides endógenos y
por otro, fármacos sintéticos agonistas y antagonistas de los receptores cannabinoides.
Palabras clave: Sistema cannabinoide. Cannabis. Cannabinoides. Dolor. Espasticidad. Náuseas y vómitos. Eficacia. Efectos indeseados.

Anestesiología y Medicina del Dolor

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