Shares of tobacco major Altria Group  (MO) - Get Report  fell Friday after a former Food and Drug Administration commissioner expressed doubts about whether e-cigarette producer Juul would see the agency clear its products for continued sale.

Richmond, Va.-based Altria holds 35% of Juul, the San Francisco producer of e-cigarettes, which contain a battery, heating element and a nicotine-infused liquid.

Makers of e-cigarettes have been allowed to sell their products in the U.S. for several years, pending regulatory review. 

"Juul is in a hard spot to ever get their product approved," Scott Gottlieb told CNBC's "Squawk Box" in an interview. "They have so much historical youth use with their product. I don't know how Juul gets through an application process."

Shares of Altria closed off 4.5% to $48 on Friday on the New York Stock Exchange.

Earlier in June the FDA moved up the deadline by which e-cigarette producers must submit their products for review, Reuters reported.

The agency had planned to give them until August 2021; a legal challenge to that date prompted FDA to reset the deadline to at least 10 months after a final court ruling on the matter, Reuters reported. The plaintiffs in the suit wanted the deadline set at 120 days, the news service reported.

Faced with scrutiny about young people's use of its products, Juul has pulled popular flavored nicotine liquids out of retail stores and shut down its social-media channels on Instagram and Facebook, Reuters reported.