Cannabinoids Don't Alleviate Acute Nociceptive Pain

Oral cannabis extract did not reduce acute pain in two well-established human pain models

WEDNESDAY, June 25 (HealthDay News) -- Orally administered cannabis extract did not produce significant analgesic or anti-hyperalgesic effects in two well-established human pain models -- sunburn and intradermal capsaicin -- according to study findings published in the July issue of Anesthesiology.

Birgit Kraft, M.D., of the Medical University of Vienna in Austria, and colleagues conducted a double-blind, crossover study of 18 healthy female volunteers, who were given capsules containing THC-standardized cannabis extract or placebo. Two established methods of inflicting pain were used: a sunburn spot, which researchers created on the upper leg; and capsaicin, injected intradermally to the forearm. Heat pain thresholds were measured at specific intervals to determine degree of pain. Secondary parameters were electrical pain thresholds, sunburn-induced secondary hyperalgesia and capsaicin-induced pain.

Oral cannabis extract intake did not reduce pain in either the sunburn or capsaicin models in any of the parameters used to measure pain, the researchers found. In the sunburn model, cannabis appeared to increase pain sensitivity using the electrical pain threshold measure, although this did not reach statistical significance, the report indicates.

"Our results do not suggest the use of cannabinoids as appropriate analgesics for the treatment of acute nociceptive pain in humans," the authors conclude. "From our data, however, no final conclusion can be drawn about their potential therapeutic efficacy in certain chronic pain conditions."

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