Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of GW Pharmaceuticals (NASDAQ:GWPH), a biopharmaceutical company focused on discovering cannabinoids and utilizing them to alter biologic pathways via the cannabinoid receptor system, jumped as much as 11% after announcing that epidiolex has received fast track designation from the Food and Drug Administration for the treatment of Dravet Syndrome, a rare and treatment-resistant form of childhood epilepsy.

So what: According to its very early morning press release, and CEO Justin Gover, "With GW having already opened an Investigational New Drug (IND) for Epidiolex, we are on track to commence a phase 2/3 clinical trial in Dravet Syndrome in the second half of this year." Fast track designation affords GW Pharmaceuticals some intriguing benefits, which include more frequent written correspondence with the FDA to facilitate drug development, as well as the potential for a priority or rolling review which may get epidiolex to market sooner if it performs well in clinical trials. In addition, GW Pharmaceutical announced that it would be conducting a clinical study involving epidiolex as a treatment for Lennox-Gastaut syndrome, another difficult-to-treat type of childhood epilepsy. GW anticipates holding a pre-IND meeting with the FDA with the next few months and then running two phase 3 studies next year.

Now what: This is certainly good news for GW Pharmaceuticals' optimists who are looking for the company to expand its global portfolio beyond just Sativex. However, I'd be truly foolish if I also didn't point out that Sativex, which has been on the market in the EU for years as a treatment for multiple sclerosis-based spasticity, brought in only $3.7 million in revenue last year – a 14% drop from the previous year. It's one thing to make pharmaceutical products derived from cannabis plants, but it's an entirely different ballgame when you try to sell it to physicians and the public apparently. One problem for GW Pharma, at least overseas, is that generic versions of Zanaflex can be prescribed for a cheaper cost than Sativex, making sales growth difficult in the EU. GW also has to overcome wide-ranging perceptions of physicians and the public as to the benefits or risks associated with marijuana plant-based cannabinoids. Even with the company running multiple phase 3 studies with Sativex in the U.S. as a treatment for cancer pain, profitability looks to be a long way off. As such, I would suggest investors consider taking their profits here and head for the exit as quickly and orderly as possible.

Marijuana stocks may seem like a great growth opportunity, but they could pale in comparison to the potential of this top stock
Give us five minutes and we'll show how you could own the best stock for 2014. Every year, The Motley Fool's chief investment officer hand-picks one stock with outstanding potential. But it's not just any run-of-the-mill company. It's a stock perfectly positioned to cash in on one of the upcoming year's most lucrative trends. Last year his pick skyrocketed 134%. And previous top picks have gained upwards of 908%, 1,252% and 1,303% over the subsequent years! Believe me, you don't want to miss what could be his biggest winner yet! Just click here to download your free copy of "The Motley Fool's Top Stock for 2014" today.

Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.