Kraft Birgit, Frickey Nathalie A, Kaufmann Rainer M, Reif Marcus, Frey Richard, Gustorff Burkhard, Kress Hans G
Department of Anesthesiology and Intensive Care Medicine A, Medical University of Vienna, Vienna, Austria.
Anesthesiology. 2008 Jul;109(1):101-10. doi: 10.1097/ALN.0b013e31817881e1.
Cannabinoid-induced analgesia was shown in animal studies of acute inflammatory and neuropathic pain. In humans, controlled clinical trials with Delta-tetrahydrocannabinol or other cannabinoids demonstrated analgesic efficacy in chronic pain syndromes, whereas the data in acute pain were less conclusive. Therefore, the aim of this study was to investigate the effects of oral cannabis extract in two different human models of acute inflammatory pain and hyperalgesia.
The authors conducted a double-blind, crossover study in 18 healthy female volunteers. Capsules containing Delta-tetrahydrocannabinol-standardized cannabis extract or active placebo were orally administered. A circular sunburn spot was induced at one upper leg. Heat and electrical pain thresholds were determined at the erythema, the area of secondary hyperalgesia, and the contralateral leg. Intradermal capsaicin-evoked pain and areas of flare and secondary hyperalgesia were measured. Primary outcome parameters were heat pain thresholds in the sunburn erythema and the capsaicin-evoked area of secondary hyperalgesia. Secondary measures were electrical pain thresholds, sunburn-induced secondary hyperalgesia, and capsaicin-induced pain.
Cannabis extract did not affect heat pain thresholds in the sunburn model. Electrical thresholds (250 Hz) were significantly lower compared with baseline and placebo. In the capsaicin model, the area of secondary hyperalgesia, flare, and spontaneous pain were not altered.
To conclude, no analgesic or antihyperalgesic activity of cannabis extract was found in the experiments. Moreover, the results even point to the development of a hyperalgesic state under cannabinoids. Together with previous data, the current results suggest that cannabinoids are not effective analgesics for the treatment of acute nociceptive pain in humans.
在急性炎症性疼痛和神经性疼痛的动物研究中显示了大麻素诱导的镇痛作用。在人类中，使用δ-四氢大麻酚或其他大麻素的对照临床试验证明了其在慢性疼痛综合征中的镇痛效果，而在急性疼痛方面的数据则不太确凿。因此，本研究的目的是调查口服大麻提取物在两种不同的人类急性炎症性疼痛和痛觉过敏模型中的作用。
作者对18名健康女性志愿者进行了一项双盲、交叉研究。口服含有δ-四氢大麻酚标准化大麻提取物或活性安慰剂的胶囊。在一条大腿上部诱发一个圆形晒伤斑。在红斑处、继发性痛觉过敏区域和对侧腿部测定热痛和电痛阈值。测量皮内辣椒素诱发的疼痛以及红斑和继发性痛觉过敏区域。主要结局参数是晒伤红斑处的热痛阈值和辣椒素诱发的继发性痛觉过敏区域。次要测量指标是电痛阈值、晒伤诱发的继发性痛觉过敏和辣椒素诱发的疼痛。
大麻提取物在晒伤模型中未影响热痛阈值。与基线和安慰剂相比，电阈值（250赫兹）显著降低。在辣椒素模型中，继发性痛觉过敏区域、红斑和自发痛均未改变。
总之，在实验中未发现大麻提取物的镇痛或抗痛觉过敏活性。此外，结果甚至表明在大麻素作用下会出现痛觉过敏状态。结合先前的数据，目前的结果表明大麻素对治疗人类急性伤害性疼痛无效。
