Sanofi-Aventis’ low molecular weight heparin Lovenox is safer and easier to manage than the current standard treatment for patients undergoing percutaneous coronary intervention (PCI) procedures such as angioplasty, according to the results of the STEEPLE trial.

A single bolus injection of Lovenox (enoxaparin) was associated with significantly less bleeding and more predictable anticoagulation levels than unfractionated heparin, according to the 3,528-patient study, which is published in the New England Journal of Medicine.

The data, which were first presented at the European Society of Cardiology last year, show that the incidence of major and minor bleeding was 31% lower in a 0.5mg/kg enoxaparin dose group compared to UFH (5.9% vs. 8.5%, p=0.01). Meanwhile, a higher, 0.75 mg/kg enoxaparin group proved to be non-inferior to UFH (6.5% vs. 8.5%, p=0.051).

Rates of heart attack and the need for additional PCI procedures were the same in all three groups, suggesting that the increase in safety with Lovenox was not counteracted by an decrease in efficacy.

The study also showed that enoxaparin is associated with a fourfold increase in the rate of patients achieving target anticoagulation levels compared with UFH (79% for enoxaparin 0.5 mg/kg and 92% for enoxaparin 0.75 mg/kg versus 20% for UFH [p<0.001]).

But an editorial accompanying the study by Bill O’Neill of the University of Miami in the USA that there is also a worrying trend towards increased 30-day mortality in the 0.5mg/kg enoxaparin group, which led the trial’s data and safety monitoring board to stop the study early. The fact that 40% of those deaths were deemed to have been possibly treatment-related – compared to no deaths in the UFH group – also raises questions, he said.

However, the authors of the study, headed by Gilles Montalescot of the Hopital Pitie Salpetriere in France, maintain that this increase is down to chance, particularly as Lovenos – one of the most studied anticoagulant agents – has not been linked to an excess risk of death before.

Meanwhile, Sanofi faces an uncertain future for Lovenox, still its top-selling drug with sales of 1.24 billion euros ($1.58bn) in the first half of this year, because of a patent challenge in the USA brought by generic drugmakers Teva Pharmaceutical Industries and Amphastar. This is due to be heard in December.

The French drugmaker has also filed a lawsuit against Novartis' generic subsidiary Sandoz for infringing Lovenox' US patents.