A European regulatory body plans to examine whether certain cholesterol drugs have long-term clinical benefits--and one potential outcome could be their withdrawal from the market if they come up short.

The review will have implications for Abbott Laboratories (ABT) and the pharmaceutical unit of Solvay SA (SVYSY, SOLB.BT), which Abbott is in the process of acquiring for $6.6 billion. Abbott and Solvay co-market the drugs TriCor and Trilipix, which are in a category the European regulatory body will assess.

The Abbott/Solvay drugs are known as fenofibrates, and are used to improve cholesterol levels and levels of fatty substances known as triglycerides. But they've never been definitively proven to prevent heart attacks and related disease. Abbott recorded $919 million in combined sales of the drugs for the nine months ended Sept. 30.

On Friday, the European Medicines Agency's Committee for Medicinal Products for Human Use announced that it began a so-called "referral procedure" to examine fenofibrates and similar drugs "because of concerns over their long-term clinical benefit in the primary and secondary prevention of cardiovascular disease."

The examination was initiated at the request of the U.K., the EMEA said. A spokeswoman for the U.K.'s drug regulator, the Medicines and Healthcare Products Regulatory Agency, declined immediate comment.

In addition to fenofibrates, the referral procedure will examine the drugs bezafibrate, ciprofibrate and gemfibrozil.

EMEA spokesman Martin Harvey said referral procedures can be launched for drugs that have been approved on a country-by-country basis, as opposed to those approved centrally by the European Commission. Referral requests generally seek a European Commission action that would apply to all member countries.

Harvey said potential outcomes of referral procedures are: leaving the drug or drugs in question on the market, changing their prescribing labels, suspending marketing authorization temporarily, or market withdrawal. He declined to estimate how long the referral procedure might take.

A recent example of a referral procedure was the EMEA's review of medicines containing methylphenidate, which treat attention-deficit hyperactivity disorder. The European agency reviewed the drugs due to concerns about their safety, and concluded earlier this year that their benefits continue to outweigh their risks. The agency did conclude that prescribing information should be made consistent across the EU, however.

Fenofibrates also are being sized up in the U.S. The National Institutes of Health has conducted a large study testing whether adding TriCor to the cholesterol-lowering drug simvastatin is any better than simvastatin alone at improving cardiovascular outcomes in diabetics. Simvastatin, which was a blockbuster seller for Merck & Co. (MRK) under the brand Zocor before it lost patent protection in 2006, has been proven to reduce cardiovascular risk in clinical trials.

Treatment in the NIH study ended in June and results are expected to be reported in early 2010. Some analysts think there's a good chance the results will be negative for TriCor.

An Abbott spokeswoman declined immediate comment. Abbott has previously defended the drugs' efficacy and safety.

-By Peter Loftus, Dow Jones Newswires; 215-656-8289; peter.loftus@dowjones.com