London, Mar 11: Bayer and GlaxoSmithKline (GSK), the makers of the newest anti-impotence drug to reach the market, say their product Levitra (vardenafil) is stronger than Viagra and another new pill for treating erectile dysfunction, Cialis.
Levitra was launched in its first market, Britain, on Tuesday. Cialis (tadalafil), made by Eli Lilly, hit the European market last month.

All three drugs work by blocking an enzyme known as PDE-5, which affects blood flow to the penis, but the merits of each drug in terms of potency, speed and duration of action are hotly disputed.

As they sought to gain a share of the multi-billion dollar market for erectile dysfunction therapies, so far dominated by Pfizer's Viagra, Bayer and GSK said Levitra had been shown in the laboratory to be a more potent inhibitor of PDE-5 than its rivals.

And in response to claims that Cialis can work all day, the companies said Levitra's half-life of four to five hours "allows patients to be confident that the drug is not circulating in the body for any longer than necessary."

The statement quoted medical specialists in erectile dysfunction (ED) as saying: "With existing therapies for ED, it is not uncommon for men to have to take the treatment five to six times before it will work for them."
Owen Collins, Bayer's head of medical sciences in the UK, said reliability rates for Levitra were "90 percent for most men, first time and time after time."

He said trials of the new drug had looked at the aspects that really mattered to men with ED--that is, the treatment should provide "erections that are hard enough for penetration, maintained for long enough and are reliable."

Levitra, which has been approved in the European Union and is expected to be approved in the United States in the second half of 2003, was developed by Bayer but will be co-promoted by GSK.

In trials involving 1,020 men with erectile dysfunction who took the drug for one year, the average success rate in maintaining erections improved from 14 percent to 82 percent with the 10 milligram (mg) dose and from 16 percent to 86 percent with the 20 mg dose.

The most common adverse effects reported were headache, flushing, stuffy nose and indigestion, events typical of PDE inhibition, the companies said.
The price of the drug in Britain is 19.34 for a pack of four 10mg tablets or 23.50 for a pack of four 20 mg tablets--identical to the price of Viagra 50 mg and 100 mg. Cialis is priced at 19.34 for four pills, irrespective of whether patients use the 10 mg or 20 mg dose. Bureau Report