To understand the analgesic potential of medical Cannabis, it is crucial to understand the relationship between the transmission mechanisms of the painful stimulus and the endocannabinoid system.
The analgesic properties of cannabinoids are basically due to the presence of CB1 cannabinoid receptors at the level of the central and peripheral nervous system. A pain stimulus comes through the nerve pathways to the spinal cord, and from there it is transmitted to areas of the brain related to pain processing. The activation of cannabinoid receptors present in both the bone marrow and the brain inhibits the transmission of these pain signals. At the peripheral level, in addition to inhibiting the transmission of signals, the activation of CB2 reduces the release of pro-inflammatory mediators at the injury site.
The endocannabinoid system is frequently located together with the most powerful and best-known pain control system: the opioid system. Both are present in the main nervous system structures involved in the transmission of pain, and a synergic effect between both systems has been observed when controlling pain.
In a study conducted by Wilsey B., they observed the reaction of thirty-eight patients with central and peripheral neuropathic pain, who underwent medical Cannabis treatment. They could verify that there was an analgesic response on these patients, besides the minimal psychoactive effects, which were well tolerated.
On the other hand, in a study conducted by “Clinical Pharmacology and Therapist,” there was no significant change in the concentration/time in morphine plasma (opioid) after Cannabis exposure, but a significant reduction of the chronic pain after the addition of vaporized Cannabis. Therefore, it was concluded that: “The vaporized cannabis increased the analgesic effects of the opioids, without significantly altering their levels in plasma, allowing this combination to reduce the doses of the drug, together with its side effects.”
Based on this data, it can be concluded that the joint administration of cannabinoids with opioids could enhance the analgesic effect. Also, they offer safety advantages, since by doing that, the needed amount of opioids is reduced, and consequently the appearance of side effects.