Cholesterol Drug May Affect Sleep

Study Shows Some Users of Zocor Report a Poorer Quality of Sleep

Medically Reviewed by Louise Chang, MD on November 07, 2007
From the WebMD Archives

Nov. 7, 2007 (Orlando, Fla.) -- Are you tossing and turning at night? A popular cholesterol-lowering drug may be to blame.

In a new study, those who took the statin drug Zocor reported they had a significantly worse quality of sleep than those who took a placebo or Pravachol, another statin drug, says researcher Beatrice Golomb, MD, an associate professor of medicine at the University of California, San Diego.

Participants did not report any specific sleep disturbance, just generally having a worse night's sleep, she says.

"Problems with sleep initiation, problems with sleep maintenance, a feeling that sleep was unrestful, and napping during the day -- none of those actually were what was going on," Golomb tells WebMD.

So what's left?

Maybe nightmares, something related to sleep-disordered breathing, or some as yet unexplored problem, Golomb says.

"Although the average effect on sleep was detrimental on Zocor, this does not mean that everyone on Zocor will experience worse sleep," she says.

The study involved 1,016 people with no signs of heart disease and LDL "bad" cholesterol levels between 115 and 190. LDL levels below 100 are optimal, according to the American Heart Association.

They were randomly assigned to Zocor, Pravachol, or a placebo for six months. Participants rated "sleep quality" and "sleep problems" on two standardized sleep scales.

Insomnia is listed as a possible side effect on the labeling of all statin drugs.

The findings were reported at the American Heart Association's (AHA) Scientific Sessions 2007.

The National Institutes of Health funded the study.

Fat-Soluble vs. Water-Soluble

Zocor and Pravachol dissolve in the body differently, says Gordon Tomaselli, MD, chairman of the committee that picked the studies to highlight at the meeting. Tomaselli is chief of cardiology at Johns Hopkins University School of Medicine in Baltimore.

Zocor dissolves in fat, so it can more easily penetrate cell membranes and cross the blood-brain barrier into the brain. Pravachol dissolves in water, so it has a hard time penetrating these barriers.

"It's easy to theorize that if you get a foreign substance in the brain, it might affect sleep, cognition and other processes controlled by the brain," Tomaselli tells WebMD.

Tomaselli says statins do not interfere with most people's sleep. "But if you are having sleep problems, ask you doctor if you should switch to a medication that has less fat solubility," he advises.

Other statins that are fat soluble include Lipitor and Mevacor. The statins Crestor and Lescol are water soluble.

Merck, the maker of Zocor, says in a statement that it conducted sleep studies with Zocor, Pravachol, and a placebo and found no difference with regard to sleep disturbances between Zocor and the placebo.

Additionally, in a study of more than 20,000 patients, people taking Zocor were no more likely to stop taking it because of sleep disorders than those on placebo, Merck says.

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SOURCES: American Heart Association's Scientific Sessions 2007, Orlando, Fla., Nov. 4-7, 2007. Beatrice Golomb, MD, associate professor of medicine, University of California, San Diego. Gordon Tomaselli, MD, chairman, AHA committee on scientific session program; chief of cardiology, Johns Hopkins University School of Medicine, Baltimore. Merck. web site. Medicine for People in Need web site.

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