LONDON (Reuters Health) - Eli Lilly said on Friday that its erectile dysfunction drug tadalafil (Cialis) could not be launched immediately in Europe following a switch in manufacturing sites.

The drug, which promises to work faster and last longer than Pfizer's sildenafil (Viagra) received approval from the European Commission yesterday.

This would normally have triggered an immediate launch at least in countries such as the UK where companies are free to set their own drug prices.

Asked what was stopping the UK launch, a spokesman for Lilly said "the European supply of Cialis was originally to be manufactured in the United States.

"However, based on our US manufacturing status, we have transferred manufacturing to a European EU site. We expect this facility will be ready in the first half of 2003."

The spokesman declined to say where the European site is based, whether the plant had been completed or whether it had regulatory approval. "This is commercially sensitive. Other companies would give their back teeth to know how quickly [the drug] will get to market."

In the United States, where Cialis has an "approvable letter" rather than full FDA approval, the spokesman said manufacturing was switching from Indianapolis to Puerto Rico.

Lilly Icos, which is a joint venture of Lilly and Icos Corp, estimates there are 31 million men in Europe with erectile dysfunction.

Viagra dominates the impotence market but competitors, such as Abbott and Takeda (Uprima) and Bayer and GlaxoSmithKline (Levitra), have filed for approval and the drugs could reach the market soon.

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