Two studies have examined the effectiveness of THC and levonantradol, a synthetic compound similar to THC, in relieving acute postoperative pain. Medical cannabis is an increasingly popular alternative to traditional pain relievers, including opioids. Cannabis can relieve certain types of chronic pain, including pain resulting from nerve damage and inflammation. In contrast, some clinical studies have not only failed to prove that THC relieves pain, but they have also found that the drug has the opposite effect.
For this reason, researchers hope to discover pain relievers that work in the body in a different way than opioids do. Because marijuana is used to treat pain in such diverse circumstances and because the IOM team determined that marijuana appears to be a promising source of pain relievers, the next chapter is dedicated to analyzing the performance of marijuana and cannabinoids in clinical trials on pain relief. However, there is still a need for further research in the area of cannabis use for chronic pain, especially in the use of different strains, doses and methods of administration. Despite a growing number of states legalizing cannabis, a major association of pain physicians has recommended not using the drug to control pain.
In a subsequent study, the same researchers compared the effects of a single potent dose of THC with those of a relatively weak narcotic analgesic, codeine. In these experiments, volunteers who experienced painful shocks, heat, or pressure from a tourniquet reported that THC actually increased their pain sensitivity. However, after critically reviewing existing research on THC and pain relief, the IOM team concluded that cannabinoids can provide mild or moderate pain relief, on a par with codeine. Comprised of more than 7,000 pain specialists from 125 countries, the IASP is the world's leading organization of pain specialists.
However, the few studies that have been conducted on the use of medical cannabis for the treatment of cancer pain have results that suggest that it has therapeutic potential, and that it at least deserves further research. Five clinical studies evaluating the effect of THC or CBD on cancer pain control were evaluated for selective review. Since most people take medications for moderate pain, it would have been more useful to assess the ability of THC to relieve pain between the extremes that were actually measured (researchers often do this by asking participants to use a numerical scale to assess the pain they feel under various conditions). For the IASP, research continues on how cannabis and cannabinoids could help patients manage pain.
The components of cannabis that most pain relief studies focus on are cannabidiol (CBD) and tetrahydrocannabinol (THC). Peripheral nerves that detect pain sensations contain abundant cannabinoid receptors, and cannabinoids appear to block peripheral nerve pain in experimental animals. This THC analog had previously been shown to block pain in animals, and its ability to relieve moderate to severe pain in cancer patients was being tested.
