Sanofi-Aventis has said its Plavix (clopidogrel) anti-thrombotic drug has been approved for marketing in Japan, the world’s second largest pharmaceutical market, for secondary prevention in patients undergoing ischemic strokes.

Sales of Plavix are scheduled to start in the second quarter after the Japanese National Health Insurance system assigns a price listing for the product. There are approximately two million people who suffer from stroke.

Last July, Daiichi Pharmaceutical and Sanofi-Aventis agreed to transfer all commercial rights for Plavix in Japan from Daiichi and their joint venture to Sanofi-Aventis Japan for antitrust reasons. Daiichi’s merger with Sankyo - which has the stroke drug prasugrel in its late-stage product pipeline - was the driver for the transfer, which completed in September 2005. Daiichi and Sanofi-Aventis will still cooperate on the drug's manufacturing and promotion.

Plavix is also in clinical trials in Japan aimed at extending its use to include patients with acute coronary syndromes.

A Japanese launch will add momentum to Plavix, already one of the pharmaceutical industry’s fastest-growing blockbuster products with sales up 23% to 534 million euros ($656m) in the third quarter of 2005, although this growth rate has slipped back a little from earlier levels of 30%-plus.