Scientists have long known that tetrahydrocannabinol (THC), the active ingredient in marijuana, is an effective painkiller. But THC's kaleidoscopic effects, including sedation, giddiness, and paranoia, limit its use in medicine. Now, researchers have fabricated a drug that alleviates pain through a mechanism similar to that of THC, but without the side effects.
The drug, dubbed AM1241, binds to one of the two types of cannabinoid receptors in the body. These protein-based switches, which sit on a cell's exterior, respond primarily to THC.
In tests with rats, the researchers targeted an ailment known as neuropathic pain. Often severe and disabling, this pain differs from the central nervous system's alarm-raising response to injury or inflammation. Animals feel neuropathic pain when the central nervous system itself goes awry. As a result, it can radiate pain signals without any stimulus or cause hypersensitivity to stimuli that would not otherwise be painful–even