There's no one way to invest in the cannabis industry. You might pick pot producers, companies with just slight exposure to the industry, or medical marijuana stocks. GW Pharmaceuticals (NASDAQ:GWPH) falls into the medical marijuana segment, but it's also a pharmaceutical company, making it an intriguing option. 

The stock's been producing some impressive sales numbers over the past year, but for risk-averse investors, it may be too dependent on the success of just one drug. Let's take a closer look to see whether you should add the stock to your portfolio today.

It's all about Epidiolex

One danger of investing in the pharmaceutical industry is that a stock's success often hinges on just one drug. GW Pharmaceuticals is no exception. Its Epidiolex drug, which treats Dravet Syndrome and Lennox-Gastaut syndrome, is a crucial part of its business. Right now, the linchpin drug is driving significant growth for the U.K.-based company. It still has many exciting growth opportunities available in the U.S. and Europe.

An orange pill bottle on its side with white pills spilling out of it onto a table.

Image source: Getty Images.

When GW Pharmaceuticals released its first-quarter results of 2020 on May 11, its revenue of $120.6 million was more than triple the $39.2 million recorded in the prior-year period. Epidiolex's net product sales were $116.1 million in Q1, or 96% of the company's total sales. Despite the challenges the COVID-19 pandemic has created for many companies, it hasn't had an adverse impact on GW Pharmaceuticals' results thus far.

While it may be concerning that GW Pharmaceuticals is so dependent on one drug, there are still many reasons to be excited about its potential; 2019 was the first full year that Epidiolex was available to patients. It posted $296.4 million in product sales for the year -- not a bad starting point.

The company is also working on other cannabis-based medicines, including Sativex, a mouth spray used to treat neuropathic pain related to multiple sclerosis. However, there's never any guarantee a potential drug will be successful. That's why investors are excited about Epidiolex -- it's gotten through the difficult parts of the process, like regulatory approval, and is now reaping the rewards.

There's still a lot more growth out there

GW Pharmaceuticals continues to work on expanding the reach of Epidiolex. It's trying to make the drug more accessible to patients who need it in the U.S., which means getting more insurers to cover the drug.

Epidiolex is currently the only cannabidiol (CBD)-based drug that the U.S. the Food and Drug Administration (FDA) has approved. With marijuana still illegal at the federal level in the U.S., it's an uphill battle for GW Pharmaceuticals to make headway and expand Epidiolex's sales, especially when not everyone's on board with CBD or convinced that it can help patients . Still, that arguably makes the growth the company has achieved thus far that much more impressive. 

In Europe, GW Pharmaceuticals completed commercial launches into two key markets in Q1, Germany and the U.K. It's also planning to enter France, Spain, and Italy later this year. Last September, the European Commission approved Epidiolex (also known as Epidyloex in Europe) to treat Dravet syndrome and Lennox-Gastaut syndrome, just as the FDA did in the U.S. That approval paves the way for Epidiolex to potentially enter all 27 countries in the European Union.

Should you buy GW Pharmaceuticals?

GW Pharmaceuticals is an exciting growth stock that doesn't expose investors to many of the same risks many recreational pot stocks possess, including the headaches surrounding legalization in the U.S.

The company is still struggling with its bottom line. Only once in the past 10 quarters has GW Pharmaceuticals recorded a profit. However, that's one of the challenges with such rapidly growing stocks: Profits are often put on the back burner in favor of growth.

Overall, given the growth the company's achieved thus far and the vast market potential it still has left, GW Pharmaceuticals is a great stock that you can buy and hold in your portfolio for many years.

Year to date, its shares are up around 20%. That's well above the S&P 500 and the 5% decline the index has seen thus far in 2020.