Glaxo claims Levitra is real threat to Viagra

GlaxoSmithKline and Pfizer stepped up their war of words yesterday, bragging about the prowess of their rival treatments for impotence.

GSK, the UK's biggest pharmaceuticals group, presented new scientific data that it hopes will make its new drug, Levitra, a serious threat to the dominance of Viagra, Pfizer's iconic little blue pill.

The pair did battle at the European Society for Sexual and Impotence Research conference, which is meeting in Hamburg. GSK said Levitra improved sexual satisfaction, while Pfizer attempted to dispel suggestions that the upstart rival worked significantly more quickly than Viagra.

Pfizer's study said 51 per cent of men could get an erection within 20 minutes when using Viagra and that "within 14 minutes of taking Viagra, 35 per cent of men achieved at least one erection that resulted in successful sexual intercourse".

GSK is attempting to differentiate Levitra, which is expected on the market next year, by saying it works more quickly than Viagra and does not have the side effect of turning some people's vision blurry or blue.

But Pfizer said Viagra was more suited to the needs of its users, citing a UK survey, which it is also presenting at the conference. The survey found that British men with erectile disfunction spend an average of 53 minutes from thinking about engaging in sexual activity to initiation of intercourse.

The survey also found that sufferers had intercourse only once in 24 hours – a claim that analysts said would be used to dismiss the attractions of a second rival drug, Cialis from Eli Lilly of the US. Cialis, also due next year, stays in the body for more than a day and has already been dubbed "le weekend" in France.

GSK, and its partner Bayer, the German group which developed Levitra, said men using its treatment were five and a half times more likely to be able to maintain erections after taking its drug than before. More than 1,000 men suffering from erectile disfunction took part in the study.

Inigo Saenz de Tejada, who led the study, said: "Patients reported sustained, improved erectile function with Levitra over a one-year period. On average, men were successful more than eight out of 10 times in maintaining an erection sufficient for sexual intercourse. Men also reported high overall sexual satisfaction."

More than £1bn of Viagra tablets were sold last year, and sales are forecast to top £1.5bn by 2005. By contrast, Deutsche Bank is currently predicting only £250m of sales for Levitra in 2005.