Analyst are unsure whether an early termination of a study comparing Merck & Co/ Schering-Plough's cholesterol drug Zetia and Abbott' Laboratories' lipid drug Niaspan is good or bad news for the former firms.

A notice has been posted on the US National Institutes of Health's online registry of clinical trials which states that an "independent steering committee has stopped the trial based on results of a pre-specified, blinded interim analysis". The notice also stresses that the Phase IV study comparing Zetia (ezetimibe) and Niaspan (extended-release niacin) “was not stopped due to safety concerns”.

The ARBITER 6-HALTS trial, which began in November 2006, was designed to compare HDL- and LDL-focused dyslipidaemia treatment strategies on carotid atherosclerosis. The primary endpoint was change in carotid intima-media thickness.

Merck shares fell on the news and Jon LeCroy, an analyst at Natixis Bleichroeder, wrote a research note saying that “we are now assuming that this trial significantly favoured Niaspan and, as a result, we are decreasing our sales estimates for both Zetia and Vytorin”, which combines ezetimibe and simvastatin.

However, Barbara Ryan at Deutsche Bank issued a note to investors saying that the “substantial weakness in Merck shares…on this development is unwarranted, in our view, based on the available information”. She noted that the trial may have been stopped for a number of reasons, such as a problem in enrolling patients.

Merck signs deal with Portola for betrixaban
Better news for Merck came with the announcement of a deal which will see the firm acquired exclusive global rights from Portola Pharmaceuticals for the oral anticoagulant, betrixaban.

Under the terms of the agreement, Merck will make an upfront payment of $50 million, while Portola could receive an additional $420 million upon the achievement of certain milestones, as well as double-digit royalties on worldwide sales, if betrixaban is approved. The drug currently in Phase II for the prevention of stroke in patients with atrial fibrillation

Merck will assume all development and commercialisation costs, while Portola has an option to co-fund late-stage studies in return for additional royalties and co-promote the Factor Xa inhibitor in the USA. A Phase III trial of betrixaban in late 2010 to evaluate the drug's ability to reduce blood-clot risk in atrial fibrillation.