Researchers in Finland have uncovered firm evidence linking deaths caused by muscle toxicity with the anti-cholesterol drug cerivastatin - marketed as Baycol and Lipobay.

Cerivastatin - produced by German pharmaceutical company Bayer - was withdrawn in August last year after being linked to the deaths of 100 people and at least 500 cases of muscle damage around the world.

At the time, Bayer said it was concerned about the co-prescribing of statins, including cerivastatin, with another cholesterol-lowering agent called gemfibrozil, to achieve more aggressive results. Now scientists from the University of Helsinki have discovered that in almost half the cases of muscle damage and death linked to the drug, the patients had also been taking gemfibrozil - marketed as Lopid.

Significantly, they found that gemfibrozil greatly increased the amount of cerivastatin in the blood. As such, the combination of the two drugs increased concentrations of cerivastatin by five to six times, and in some people up to 10 times, creating a rare but serious muscle toxicity.

Combinations of lipid-lowering drugs are used for treating certain disorders and the researchers say mixing statin-type cholesterol-lowering drugs like cerivastatin can have a potentially adverse effect, although such a reaction is rare. The risk of muscle toxicity rises when blood concentrations increase too much.

Gemfibrozil has been found to moderately increase the muscle toxicity of other statin treatments such as simvastatin, but with careful management, both can be prescribed together, the Finnish team say.

Bayer, the first patented manufacturer of aspirin, has been hit hard by the costly recall of Baycol, which was rapidly becoming one of the company's best-selling drugs.