In recommending measures to manage the contamination of heparin-containing medicines, regulators in the European Union have decided that Sanofi-Aventis’ anticoagulant blockbuster Lovenox should stay on the market.

The European Medicines Agency has finished a review of the risks associated with the use of heparin medicinal products contaminated with oversulphated chondroitin sulphate (OSCS) since the first reports of tainted heparin products came through from the USA in March. As part of this, the agency’s Committee for Medicinal Products for Human Use (CHMP) has been looking at Lovenox (enoxaparin), a low molecular weight heparin which is Sanofi's top-selling drug, with sales in the first quarter of 717 million euros (+21.5%).

Some low levels of impurity have been found in some batches of Lovenox, but the CHMP says that “a total removal of contaminated enoxaparin from the market in countries where it is used would lead to a shortage of supply and patients would not be able to continue their treatment”. High levels of contamination with OSCS have been found in standard heparin from China, notably Baxter and Rotexmedica’s products which were linked with serious side effects and over 80 deaths, but no similar adverse events have been observed with Lovenox.

The CHMP concluded that doctors can continue to use enoxaparin with low levels of OSCS “to treat patients temporarily until the situation is resolved”. However, physicians have been told that intravenous or intra-arterial administration of the drug should be avoided and patients should be monitored closely for signs of allergic reactions. Also, pregnant women should not be given contaminated enoxaparin.

The news from the EMEA meant that Sanofi ended the week on a positive note, coming days after UK regulators revealed data which suggested that the anti-obesity treatment Acomplia (rimonabant) was linked to five deaths. That followed the European Commission’s decision to open formal proceedings against the French-based firm, claiming it obstructed inspectors who carried out dawn raids at its premises, and those of many other drugmakers, in January.