Russia: Viagra maker sues over cheaper rival

Russian men looking to improve sexual performance on the cheap will lose their cut-price medicinal assistance if the pharmaceutical giant Pfizer is successful in a lawsuit against a generic competitor to its drug Viagra.

Pfizer says that Teva, a pharmaceutical company, is violating a patent, valid until 2014, that Pfizer holds to sell sildenafil-based medicines for treating erectile dysfunction.

A spokesman for Pfizer said Teva was already importing and selling its treatments on the Russian market, and the company said it would "take all necessary measures" to protect its brand.

Sildenafil, the active ingredient in Viagra, was initially developed to treat heart-related conditions, but during clinical trials it turned out that men experienced spontaneous erections. It was launched as Viagra in 1998 and re-patented in 2002 as a treatment for erectile dysfunction.

In the United States, Pfizer won a lawsuit against Teva last month, which bans the competitor from launching the drug until 2019. The US is by far the biggest market for the drug, and accounts for around half of all sales.