A British pharmaceutic firm is completing clinical trials of a drug derived directly from marijuana and hopes to receive approval to market it from the Food and Drug Administration by the end of 2013.

The drug, which contains both THC and cannabidiol, has already been approved in Canada, New Zealand, and several European countries to relieve muscle spasms associated with multiple sclerosis. In the US, however, it would be sold to relieve cancer pain.

The FDA began approving drugs based on synthetic equivalents of the active ingredients in marijuana in 1985, but this would be the first drug derived from the plant itself. This is significant because, as the Associated Press points out, “The U.S. Drug Enforcement Administration categorizes pot as a dangerous drug with no medical value, but the availability of a chemically similar prescription drug could increase pressure on the federal government to revisit its position.”