The makers of a popular cholesterol lowering drug have posted results of a study showing it was ineffective—but only after a Congressional inquiry was set up to look into why they had not published their results two years after the study was completed.

Merck and Schering-Plough Pharmaceuticals, manufacturers of ezetimibe (Zetia), posted results on their websites earlier this month showing that 356 people treated with ezetimibe (10 mg) plus simvastatin (80 mg) fared no better than 360 who had received simvastatin alone (www.sch-plough.com/schering_plough/news/release.jsp?releaseID=1095943).

The study, known as the ENHANCE (Effect of Combination Ezetimibe and High-Dose Simvastatin vs Simvastatin Alone on the Atherosclerotic Process in Patients with Heterozygous Familial Hypercholesterolemia) trial, measured the thickness of carotid artery intima media as its primary end point. Although ezetimibe did cause an additional lowering of cholesterol, plaque progression was worse in the ezetimibe arm.

Ezetimibe, sold singly as Zetia or in combination with simvastatin as Vytorin, has become a blockbuster drug since it was approved in 2002, with an estimated $5bn (£2.6bn; €3.4bn) in sales in 2006. The Congressional investigation into the delayed publication of the ENHANCE trial results, which is ongoing, is now being followed by another Congressional investigation that will scrutinise claims …