At the end of what it refers to as a difficult second quarter, Sanofi-Aventis has posted a 6.3% decline in net income to almost 1.68 billion euros, hurt by generic competition and unfavourable exchange rates, and announced plans to buy back up to 3 billion euros worth of shares before May 2008.

Sales rose 2.3% to around 6.94 billion euros, while pharmaceuticals inched up 1.2% to 6.32 billion euros. The most striking feature was the decline in income suffered by Stilnox/Ambien (zolpidem) sleeping pill franchise as the quarter saw a whole host of copycat versions hit the market after US patent protection was lost.

Ambien sales sank 41.8% to 252 million euros, a bigger fall than analysts had predicted, while generic versions of the cancer drug Eloxatin (oxaliplatin), this time in Europe, led to a 10.2% revenue decline to 380 million euros. Nevertheless, there were also a number of bright points.

Having won a high-profile patent case in the USA, Sanofi could finally celebrate an increase in sales of its bloodthinner blockbuster Plavix (clopidogrel), up 12.7% to 632 million euros, its first quarterly rise since Canadian drugmaker Apotex flooded the US market with its generic version in the summer of 2006.

The antithrombotic Lovenox (enoxaparin) leapt 15.5% to 671 million euros and Hanspeter Spek, executive vice president for pharmaceutical operations, said on a conference call that its position as market leader is set to continue despite the prospect of generic versions becoming available soon.

There were also strong showings for Allegra (fexofenadine) for allergies, up 13.8% to 198 million euros, while cancer drug Taxotere (docetaxel) sales were up 9% to 474 million euros. The diabetes drug Lantus (insulin glargine) shot up 26.1% to 503 million euros, but Amaryl (glimepiride) for diabetes was down 8.8% to 103 million euros.

The second quarter for Sanofi was dominated by the withdrawal of its marketing application to gain approval in the USA for its obesity drug Acomplia (rimonabant) after a US Food and Drug Administration advisory panel voted unanimously against recommending it. Sales of the treatment elsewhere reached 22 million euros and Sanofi said that it has not given up on getting Acomplia approved across the Atlantic.

However Sanofi’s enthusiasm does not seem to be shared by investors and at 10.20 this morning, the shares had fallen 4.2% to 58.93 euros. Observers have also said that the buyback plan is not as large as had been expected and all eyes will now be on the firm’s R&D day in September to see whether the stock will recover some of its former glory.