E-cigarettes could be available on Britain's National Health Service (NHS) by the end of the year, with at least two companies - one a subsidiary of British American Tobacco - having already embarked on obtaining licences from the medicines regulator.
The British company Nicolites said its application was well advanced, while BAT's Nicoventures had also started the process.
Decisions on whether these products are prescribed on the NHS will be made by local commissioning groups.
The status of "medicines" will give the firms commercial advantage and allow makers of e-cigarettes to market products internationally, including in sponsorship deals, a move that will be banned for competitors not in the same bracket.
The news emerged as ministers in England prepared to ban e-cigarette sales to under 18s. Wales and Scotland were likely to follow suit.
The Advertising Standards Agency is also about to start consulting on rules to cover e-cigarettes, used by 1.3 million people in Britain last year.
The applications to the Medicines and Healthcare Regulatory Authority are a victory for the regulator's determination to persuade manufacturers and importers to apply voluntarily for a licence.
The application process is continuing even though the European parliament defeated British attempts to make medicinal licensing compulsory for e-cigarettes last autumn.
The readiness of big e-cigarette makers to take the costly, voluntary route for medicines approval contrasts with the position of the British trade body for e-cigarettes, Ecita, which has railed against perceived over-regulation in the EU.