Tetrahydrocannabinol (THC) and some other cannabinoids, either from the Cannabis sativa plant or synthetic, have analgesic properties, although the use of cannabis derivatives is currently illegal in many countries. A recent study finds that inhaled cannabis is effective in alleviating neuropathy and pain resulting from, e.g., spinal injury and multiple sclerosis.[21] Other psychotropic analgesic agents include ketamine (an NMDA receptor antagonist), clonidine and other α2-adrenoreceptor agonists, and mexiletine and other local anaesthetic analogues.