A new compound has been developed that is like the active compound of marijuana in relieving neuropathic pain but without the side effects of the drug, claim scientists.
The synthetic cannabinoid (cannabis-related) compound, called MDA19, seems to avoid the side effects by acting mainly on one specific subtype of the cannabinoid receptor.
"MDA19 has the potential for alleviating neuropathic pain without producing adverse effects in the central nervous system," said Dr Mohamed Naguib of The University of Texas.
The researchers performed a series of experiments to analyze the pharmacology and effects of the synthetic cannabinoid MDA19. There are two subtypes of the cannabinoid chemical receptor: CB1, found mainly in the brain; and CB2, found mainly in the peripheral immune system.
MDA19 was designed to have a much stronger effect on the CB2 receptor than on the CB1 receptor. In humans, MDA19 showed four times greater activity on the CB2 receptor than on the CB1 receptor.
In rats, treatment with MDA19 effectively reduced specific types of neuropathic pain, with greater effects at higher doses. At the same time, it did not seem to cause any of the behavioral effects associated with marijuana.
"[W]ith functionally selective drugs, it would be possible to separate the desired from the undesired effects of a single molecule through a single receptor," said Naguib.
This means that MDA19 could be a promising step towards developing medications that have the pain-reducing effect of cannabinoids while avoiding the mental and physical side effects of marijuana itself.
The findings were published in Anesthesia and Analgesia, official journal of the International Anesthesia Research Society.