"There are a number of firsts," Dr Geoffrey Guy, chairman of GW Pharmaceuticals, told CNBC after the treatment's official launch.
As well as being the first prescription medicine derived from cannabis, Sativex is also the first new treatment for multiple-sclerosis patients for over 20 years, Guy pointed out.
- Watch Dr Geoffrey Guy interviewed above.
"Today's launch means that MS patients suffering the spasms and cramping associated with spasticity have access to a new treatment option which has been shown to improve their symptoms where current treatments have failed," the company said in a press release.
GW will receive a 10 million pounds ($14.8 million) milestone payment under the terms of its agreement with Bayer because of the UK approval, the company said.
Now GW hopes to convince Britain's National Institute for Health and Clinical Excellence (NICE) that the drug is cost-efficient enough for widespread use on the UK's National Health Service, Reuters pointed out.
The UK approval was in conjunction with Spain and GW expects to gain approval there shortly with a launch slightly later in the year. Sativex will then be rolled out throughout through Europe via the Mutual Recognition Procedure, according to Guy.
GW is also looking to launch the product in the U.S., but as a treatment for cancer pain instead, Guy told CNBC. The company is about to enter Phase III trials in cancer pain and will apply for Food and Drug Administration approval after these trials are completed.
U.S. sales for cancer pain alone could exceed $500 million, with GW receiving royalties of 20-30 percent, Richard J. Parkes, senior research analyst at Piper Jaffray, wrote in a research note.
GW is looking beyond the launch of Sativex and thinks that there is a whole swathe of potential medicines that can be derived from molecules in the cannabis plant known as cannabinoids.
The knowledge gained from establishing the treatment puts the company in a strong position to develop them, Justin Gover, managing director at GW Pharmaceuticals, told CNBC.com.
"Once we have demonstrated that we can get approval for a drug like Sativex it gives us a greater level of confidence that approval will be forthcoming in the future for our pipeline of cannabinoid products," he said.
By proving that a cannabis-based drug can get over the regulatory hurdles, the company could be at risk of generic competition because other companies, encouraged by this, may go ahead and develop their own drugs, Jeffrey Miron, senior lecturer in economics at Harvard University, told CNBC.com.
"It's always a risk but in our industry we always seek to protect against that through patent protection rights… We think that the protection for Sativex is strong," Gover said.
Eventually the drug will come off its patent, Gover pointed out. But GW hopes the period of exclusivity will more than pay off the huge investment needed to bring a new medicine to market, he said.
The treatment could also see competition from the crude form of the drug, according to Joel Hay Professor, professor of pharmaceutical economics and policy at the University of Southern California.
"The irony here is that once medical marijuana is approved no company has any ability to sell their legitimate marijuana product," Hay said.
"They can't compete against cheap medical marijuana so you won't see GW doing well," he added.
Gover disagrees and thinks patients deserve the reassurance of a fully regulated and tested treatment. Plus, a drug like Sativex is a specifically formulated product designed to tackle very particular symptoms, he said. Crude cannabis will have a variety of effects that are often unpredictable, he added.