A new anti-impotence drug for men that has yet to be approved by authorities in the United States went on sale in Britain yesterday.
Cialis - billed as a techno-logically-advanced rival to Viagra - was launched in London with a fanfare of publicity by its US makers, a collaboration between pharmaceutical giant Eli Lilly and biotechnology company Icos.
Its makers boast that their new erectile dysfunction medication starts working faster and lasts longer than Viagra.
"What we have seen from clinical trials is that Cialis allows a man following sexual stimulation to have an erection when he or his partner chooses for up to 24 hours," said Dr Susan Griffith, medical director at Lilly UK.
Available only on prescription, and costing around £30 for a pack of four pills, Cialis is said to start taking effect after just 16 minutes.
In contrast, Viagra users have to wait for an hour after swallowing the famous blue pill, while its effects only last for around four hours.
Cialis gained approval from authorities in Europe last November, with production difficulties delaying the drug's launch until yesterday.
But the federal food and drug administration has yet to approve the new medication for prescription in the US, having withheld its approval pending further information. The two makers are also fighting over patents against Pfizer, which manufactures Viagra.
Cialis and Viagra work by blocking a natural enzyme named PDE5 to increase blood flow to the penis during sex.
Cialis's backers are confident the drug will eventually go on sale in the US later this year.
At stake is the billion-pound market for anti-impotence drugs. Pfizer earned $1.7bn (£1.1bn) from worldwide sales of Viagra last year.
Viagra's status as the world's most famous anti-impotence medication is under threat from another new drug named Levitra, being jointly developed by Glaxo SmithKline and Bayer.
Levitra's release later this year promises to set off a fierce marketing war between the three rivals, for the lion's share of a market that is estimated by analysts to be worth more than £3bn by 2006. In Britain, as many as 2.3 million men suffer from erectile dysfunction. Only 10% of sufferers receive treatment, suggesting that potential sales of Viagra, Levitra and Cialis could be even larger than expected.
Pfizer are not the only organisation battling against the launch of Cialis - members of the Cialis family are up in arms about the sudden prominence of their surname.
The British arm of the Cialis family was alerted to the name when the makers first announced it two years ago, and are planning a family meeting soon to consider their options.
"We were hoping against hope that they would drop the name but now they go ahead in spite of our protestations," said Russell Cialis, a public relations executive.
"Imagine how Mr Viagra would feel, if there was one."
Like the launch of Viagra five years ago, Cialis also promises to be a bonanza for unscrupulous suppliers: dozens of websites offering Cialis for sale have already sprung up across cyberspace.
