Sanofi heparin drug impurity found in 4 countries

By Ben Hirschler

LONDON (Reuters) - Batches of Sanofi-Aventis's blood-thinning heparin injection Lovenox have been found to contain small amounts of impurity in Britain, Sweden, Spain and Australia, officials said on Thursday.

Lovenox is Sanofi's top-selling drug, with sales last year of 2.6 billion euros ($4.1 billion).

Sanofi spokesman Salah Mahyaoui said the problem only involved a small number of batches and there were no reports of patient injuries.

"It affects a very limited number of batches ... and it's very low concentration (of impurity)," he said by telephone from Paris.

The Swedish Medical Products Agency said it was withdrawing a small number of contaminated batches of the drug, which is also known as Clexane or Klexane, as a precaution.

The move follows similar withdrawals by Australian authorities on Wednesday and by Spanish regulators last week, Mahyaoui said.

In Britain, the Medicines and Healthcare products Regulatory Agency stopped short of withdrawing the product. It said doctors could continue to use the drug but should be vigilant to any adverse reactions.

It added there was currently no evidence that the presence of very small amounts of over-sulphated chondroitin sulphate in the medicine was associated with any risk to patients.