Sir Andrew Witty, CEO of pharmaceutical giant GlaxoSmithKline, was one of several pharma executives who spoke at Davos against the U.K. leaving the EU. GlaxoSmithKline

A number of leaders in the pharmaceutical industry are calling the potential exit of Great Britain from the European Union "a mistake," reports the Financial Times. The "Brexit," as it is commonly referred to, would have less of an immediate impact on sales as it would on drug discovery, according to these executives. But it would still lead to an overall negative outcome.

The pharmaceutical industry benefits greatly from as much intra-country cooperation as possible in Europe, particularly from a regulatory standpoint. Currently, most drugs are approved for sale in EU countries by the centralized European Medicines Agency, which gives drugmakers a single marketing authorization that can even be used in European Economic Area countries like Iceland and Norway.

Going through one approval process for a new drug is vastly preferable to a piecemeal approach, particularly given other complicating factors like contracts and negotiations with massive government healthcare providers in many EU nations.

“Europe has gone from 27 fragmented, independent, not-talking-to-each-other regulatory authorities in the healthcare space to one. That’s a big deal,” said GlaxoSmithKline CEO Sir Andrew Witty at Davos last week.

But it's not just regulatory processes that concern the heads of drugmakers like GlaxoSmithKline, Eli Lilly and Merck. Withdrawing from the EU would likely have a negative impact on scientists' funding.

According to one British member of Parliament, £8.5 billion (approximately $12.1 billion) in EU funding for science and technology could be threatened if the U.K. decides to leave the union.

Though based in the U.S., Eli Lilly has 2,800 employees in the United Kingdom. Many are involved in new drug discovery and research. “We tend to think about our U.K. operation . . . as being very much a European center,” Eli Lilly CEO John Lechleiter told the FT.

According to an ICM poll, support among U.K. voters for the "Brexit" from the EU was at 41 percent in December 2015, while 42 percent think Britain should remain a part of the EU. Voting on the referendum will take place by 2017.