Are Cannabinoids Really Analgesics?

Acute pain conditions: Only inconsistent data exist from controlled clinical trials with cannabinoids on acute pain. In the 80ies, two small-sized studies investigated the parenterally applied synthetic cannabinoid levonandradol in postoperative pain. Two other, more recent trials were performed with oral cannabinoids. Whereas in the smaller trial by Buggy et al. no significant analgesia was produced by a single oral dose of 5mg THC, a well-designed multicenter dose-escalation trial using oral cannabis extract showed a small, but significant dose-related reduction of postoperative patient-controlled analgesia requirements. But the dose-escalation was associated with an increased severity and incidence of side effects. In trials using human pain models of acute nociceptive or inflammatory pain and hyperalgesia, 20mg of oral THC or cannabis extract failed to produce significant analgesic effects, moreover, hyperalgesia and decreased pain thresholds were found. Interestingly enough, similar results were seen in postoperative pain after 2mg nabilone. Significantly higher pain scores were reported compared to placebo, ketoprofen or only 1mg nabilone. As recently shown by Wallace et al., not only oral cannabinoids, but also a high-dose smoked cannabis produced hyperalgesia, whereas an analgesic effect on capsaicinevoked spontaneous pain was reported after the medium dose, demonstrating an complex and not well understood dose dependency. To conclude, in most of the studies, cannabinoids proved more or less ineffective and side effects occurred frequently. Therefore they cannot be recommended for the treatment of acute pain.