pain is a very good target for therapeutic cannabinoids. Many Endocannabinoids, plant cannabinoids and cannabinoid receptors have been linked to pain management or analgesia. After many preclinical studies and clinical trials cannabinoids are emerging as safer and more potent alternatives to opioids in pain management.
In a mouse study, the endocannabinoid system was found to be required for the analgesic action of acetaminophen (paracetamol); FAAH breaks down acetaminophen to AM404 (first identified as synthetic cannabinoid but also displaying endocannabinoid activity), which in turn blocks re-uptake of Anandamide (Mallet et al., 2008).
The analgesic effect of paracetamol thus seems to be due to increased ambient levels of Anandamide.
Similarly, ibuprofen was found to block the breakdown/hydrolysis of Anandamide (Fowler et al., 1999), which may contribute to the analgesic effect of ibuprofen (and similar substances).
In mice, inhibition of opioid-degrading enzymes potentiates the analgesic effect of THC, suggesting cross talk or synergy between the opioid- and endocannabinoid systems in pain management (Reche et al., 1998).
In humans, on the other hand, THC was found not so much to enhance the analgesic effect of Morphine but to inhibit the experienced discomfort that is normally associated with pain (Roberts et al., 2006).
TRPs bind to most plant cannabinoids and Endocannabinoids with varying affinities (De Petrocellis et al., 2011, 2012), tentatively making TRPs excellent targets and plant cannabinoids excellent substrates for pain management.
The interaction between CBG and the α2 receptor (alpha 2 adrenalin receptor) may prove effective in pain control (Giovannoni et al., 2009).
Bagüés, A., Martín, M.I., and Sánchez-Robles, E.M. (2014). Involvement of central and peripheral cannabinoid receptors on antinociceptive effect of tetrahydrocannabinol in muscle pain. Eur. J. Pharmacol. 745C, 69–75.
Bertolini, A., Ferrari, A., Ottani, A., Guerzoni, S., Tacchi, R., and Leone, S. (2006). Paracetamol: new vistas of an old drug. CNS Drug Rev. 12, 250–275.
Deliu, E., Sperow, M., Console-Bram, L., Carter, R.L., Tilley, D.G., Kalamarides, D.J., Kirby, L.G., Brailoiu, G.C., Brailoiu, E., Benamar, K., et al. (2015). The Lysophosphatidylinositol Receptor GPR55 Modulates pain Perception in the Periaqueduactal Grey. Mol. Pharmacol.
Fowler, C.J., Janson, U., Johnson, R.M., Wahlström, G., Stenström, A., Norström, K., and Tiger, G. (1999). Inhibition of Anandamide hydrolysis by the enantiomers of ibuprofen, ketorolac, and flurbiprofen. Arch. Biochem. Biophys. 362, 191–196.
Ghafouri, N., Ghafouri, B., Larsson, B., Stensson, N., Fowler, C.J., and Gerdle, B. (2013). Palmitoylethanolamide and stearoylethanolamide levels in the interstitium of the trapezius muscle of women with chronic widespread pain and chronic neck-shoulder pain correlate with pain intensity and sensitivity. pain 154, 1649–1658.
Giovannoni, M.P., Ghelardini, C., Vergelli, C., and Dal Piaz, V. (2009). Alpha2-agonists as analgesic agents. Med. Res. Rev. 29, 339–368.
Mallet, C., Daulhac, L., Bonnefont, J., Ledent, C., Etienne, M., Chapuy, E., Libert, F., and Eschalier, A. (2008). endocannabinoid and serotonergic systems are needed for acetaminophen-induced analgesia. pain 139, 190–200.
De Petrocellis, L., Ligresti, A., Moriello, A.S., Allarà, M., Bisogno, T., Petrosino, S., Stott, C.G., and Di Marzo, V. (2011). Effects of cannabinoids and cannabinoid-enriched Cannabis extracts on TRP channels and endocannabinoid metabolic enzymes. Br. J. Pharmacol. 163, 1479–1494.
De Petrocellis, L., Orlando, P., Moriello, A.S., Aviello, G., Stott, C., Izzo, A.A., and Di Marzo, V. (2012). cannabinoid actions at TRPV channels: effects on TRPV3 and TRPV4 and their potential relevance to gastrointestinal inflammation. Acta Physiol. Oxf. Engl. 204, 255–266.
Reche, I., Ruiz-Gayo, M., and Fuentes, J.A. (1998). Inhibition of opioid-degrading enzymes potentiates delta9-tetrahydrocannabinol-induced antinociception in mice. Neuropharmacology 37, 215–222.
Roberts, J.D., Gennings, C., and Shih, M. (2006). Synergistic affective analgesic interaction between delta-9-tetrahydrocannabinol and Morphine. Eur. J. Pharmacol. 530, 54–58.
Positive outcome: cannabinoids were found to synergistically increase the analgesic effect of opioids by 27% (compared to opioids alone) (Abrams et al., 2011).
The effect was positively correlated with cannabis dose.
Apart from analgesia, smoked cannabis improved sleep.
Oral cannabis extract was found to effectively reduce post-operative pain (Holdcroft et al., 2006).
Negative outcome: One clinical trial has tested the efficacy of smoked cannabis on pain relief in patients with Cluster Headache.
Cannabis did not prove effective in this study (Leroux et al., 2013).
Ellis, R.J., Toperoff, W., Vaida, F., van den Brande, G., Gonzales, J., Gouaux, B., Bentley, H., and Atkinson, J.H. (2009). Smoked medicinal cannabis for neuropathic pain in HIV: a randomized, crossover clinical trial. Neuropsychopharmacol. Off. Publ. Am. Coll. Neuropsychopharmacol. 34, 672–680.
Holdcroft, A., Maze, M., Doré, C., Tebbs, S., and Thompson, S. (2006). A multicenter dose-escalation study of the analgesic and adverse effects of an oral cannabis extract (Cannador) for postoperative pain management. Anesthesiology 104, 1040–1046.
Johnson, J.R., Lossignol, D., Burnell-Nugent, M., and Fallon, M.T. (2013). An open-label extension study to investigate the long-term safety and tolerability of THC/CBD oromucosal spray and oromucosal THC spray in patients with terminal cancer-related pain refractory to strong opioid analgesics. J. pain Symptom Manage. 46, 207–218.
Klooker, T.K., Leliefeld, K.E.M., Van Den Wijngaard, R.M., and Boeckxstaens, G.E.E. (2011). The cannabinoid receptor agonist delta-9-tetrahydrocannabinol does not affect visceral sensitivity to rectal distension in healthy volunteers and IBS patients. Neurogastroenterol. Motil. Off. J. Eur. Gastrointest. Motil. Soc. 23, 30–35, e2.
Kraft, B., Frickey, N.A., Kaufmann, R.M., Reif, M., Frey, R., Gustorff, B., and Kress, H.G. (2008). Lack of analgesia by oral standardized cannabis extract on acute inflammatory pain and hyperalgesia in volunteers. Anesthesiology 109, 101–110.
Leroux, E., Taifas, I., Valade, D., Donnet, A., Chagnon, M., and Ducros, A. (2013). Use of cannabis among 139 cluster headache sufferers. Cephalalgia Int. J. Headache 33, 208–213.
Ware, M.A., Wang, T., Shapiro, S., Robinson, A., Ducruet, T., Huynh, T., Gamsa, A., Bennett, G.J., and Collet, J.-P. (2010). Smoked cannabis for chronic neuropathic pain: a randomized controlled trial. CMAJ Can. Med. Assoc. J. J. Assoc. Medicale Can. 182, E694–E701.