Merck/Schering-Plough Pharmaceuticals have announced a large scale clinical outcomes trial that will be conducted for Vytorin (ezetimibe/simvastatin).

The trial known as IMPROVE IT (Improved Reduction of Outcomes: Vytorin Efficacy International Trial) will evaluate the risk reduction provided by Vytorin 10/40 mg as compared to Zocor (simvastatin) 40 mg in reducing death and major coronary events in approximately 10,000 patients with acute coronary syndromes (ACS).

In clinical trials, Vytorin has been shown to provide superior LDL cholesterol lowering as compared to Lipitor or Zocor. The intent of the study is to determine whether Vytorin provides incremental reductions in cardiovascular events in these patients as compared to simvastatin. The primary endpoint of the trial is the composite of death, myocardial infarction (MI), rehospitalization for ACS or revascularization (occurring 30 days or more after the initial event), according to a Merck release.

"The purpose of IMPROVE IT is to evaluate the potential incremental impact of Vytorin versus simvastatin alone in reducing mortality and morbidity in high risk patients with ACS by dramatically lowering LDL cholesterol through dual inhibition," said Eugene Braunwald, Professor of Medicine, Harvard Medical School, chairman TIMI Study Group, Brigham and Women's Hospital.

IMPROVE IT is a multi-centre, randomized, double-blind active comparator study that will enrol approximately 10,000 patients with ACS, including unstable angina (UA), non-ST-segment elevation acute myocardial infarction (NSTEMI) and ST-segment elevation acute myocardial infarction (STEMI).

"There is growing clinical evidence that intensive lipid lowering provides additional benefits to high-risk patients. Improve IT will potentially provide further clinical evidence on how best to manage high-risk patients with ACS. It will also further characterize the clinical profile of Vytorin beyond its already demonstrated significant efficacy in LDL cholesterol reduction," said Robert M. Califf, professor of medicine, director, Duke Clinical Research Institute, Duke University Medical Centre.

ACS includes unstable angina (UA), non ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI) patients. ACS is usually caused by the buildup of plaque (deposits of fat-like substances) in the coronary arteries of the heart. These plaques may tear or rupture, leading to the formation of a blood clot which may partly or completely block the blood flow in a coronary artery, abruptly limiting the supply of oxygenated blood to a portion of heart muscle.

Merck/Schering-Plough Pharmaceuticals is a joint venture between Merck & Co Inc. and Schering-Plough Corporation formed to develop and market in the United States new prescription medicines in cholesterol management. The collaboration was expanded to include worldwide markets (excluding Japan).