The Food and Drug Administration fired another shot across the bow of the electronic cigarette industry Thursday, warning five companies that their products need to be approved as drugs and/or drug delivery devices and calling on other companies to meet with the agency to discuss obtaining marketing approval.

The agency had previously warned consumers that many electronic cigarettes contained dangerous chemicals, and it has taken steps to block the import of many such products — an action that is now the subject of litigation from the producers.

Thursday’s action suggests that the FDA will be even more vigorous in policing e-cigarettes, which are intended as a replacement for cigarettes and cigars.

Although some manufacturers and consumers fear that the agency is planning to ban the products, the agency is “interested in finding out whether e-cigarettes can be proven safe and effective,” Michael Levy, director of the FDA’s division of new drugs and labeling compliance, said in a news conference.

The electronic cigarettes, commonly called e-cigs, are battery-powered devices containing a cartridge of nicotine and other additives, but no tobacco. The battery vaporizes the liquid so that it is delivered to the lungs when a user inhales through the e-cig. Water vapor simulates the appearance of smoke.

The FDA objects on two points. The e-cigs are clearly a device meant to deliver a drug — nicotine — and the products’ labeling and websites promote them as an aid to stopping smoking, which is a medical claim prohibited under the Federal Food, Drug and Cosmetic Act. Levy said the agency also wants to ensure that the products are manufactured safely.

Warning letters were sent to five companies: E-Cig Technology Inc. of Las Vegas; E-CigaretteDirect of Parker, Colo.; Ruyan America Inc. of Minneapolis; Gamucci America, which also goes by the name Smokey Bayou Inc., of Jacksonville, Fla.; and Johnson Creek Enterprises of Johnson Creek, Wis.

All were warned that, because their products are marketed as stop-smoking aids, the companies must obtain preapproval by the FDA.

E-Cig Technology also was warned that it cannot sell drugs in unapproved liquid form for use in the devices, such as the erectile dysfunction drug tadalafil and the weight-loss drug rimonabant, which is not approved for sale in the United States.

Ruyan was warned for marketing cartridges containing lobelia, which it calls an herbal remedy/dietary supplement. Johnson Creek Enterprises was cited for failure to establish quality control and testing procedures required under the federal act.

The companies have 15 days to respond, after which “we will evaluate what to do,” Levy said.

The agency also sent a letter to the Electronic Cigarette Assn. outlining the procedures that must be followed to obtain marketing approval for products making medical claims and urging its members to work with the agency to obtain such approval.

The letter was addressed to Matt Salmon, president of the association. In a telephone interview, however, Salmon said that he resigned nine months ago and that, as far as he knows, the group has disbanded.

E-cigarette manufacturers have resisted the agency’s efforts to regulate them, arguing that the products should be treated just like the tobacco products they are meant to replace.

thomas.maugh@latimes.com