(Adds background on Cialis, Viagra, regulatory issues)
NEW YORK, May 28 (Reuters) - Sanofi and Eli Lilly and Co on Wednesday said they would ask health regulators for permission to sell Cialis, the world's top-selling anti-impotence drug, without a prescription.
Currently available by prescription only, the tablet was first approved by the European Medicines Agency in 2002 and then by the U.S. Food and Drug Administration in 2003.
It is one of Lilly's biggest products, having generated almost $2.2 billion in worldwide sales last year. The drug is also approved to treat enlarged prostate glands.
Under the terms of the agreement, Sanofi is buying the exclusive rights to apply for approval of Cialis tablets over the counter in the United States, Europe, Canada and Australia. Terms of the licensing agreement were not disclosed.
The tablet would be sold by Sanofi's consumer healthcare unit, which had sales last year of $4.1 billion from a wide array of non-prescription brands, including vitamins and treatments for allergies, coughs, colds and the flu.
It remains to be seen, however, whether regulators will allow Cialis to be sold without a prescription, in view of possible side effects. Like rival anti-impotence drugs, such as Pfizer Inc's Viagra, Cialis can cause a dangerous fall in blood pressure if taken with nitrates, a class of heart drugs that include nitroglycerin.
The U.S. Food and Drug Administration, in weighing whether to allow prescription drugs to be sold over the counter, weighs whether patients are able to understand complex aspects of their disease, or exactly when to take the drug to ensure safe use.
The FDA in 2008, for instance, rejected Merck & Co's bid to sell its Mevacor cholesterol-lowering drug without a prescription, after an independent panel of medical experts expressed concern that patients might take it instead of more-effective newer medicines.
Cialis will face competition from cheaper generics in the United States in 2017, the same year that Teva Pharmaceuticals Industries is expected to begin selling generic prescription forms of Viagra under an agreement reached with Pfizer last year.
Viagra, the first drug to treat impotence, was approved by U.S. regulators in 1998. It has annual sales of about $1.5 billion.
Reporting by Ransdell Pierson; Editing by Nick Zieminski