Lipophilic means the drug is soluble in fat, while hydrophilic means it is soluble in water. Previous research had implicated lipophilic statins in sleep disturbances.
"Simvastatin is fat-soluble, and can penetrate and cross into the brain," Smith explained.
Golomb said: "We did show significant worsening in both sleep quality outcome and sleep problem categories in patients taking simvastatin. Less sleep quality and more sleep problems."
Those participants who had worse sleep also showed a worsening in their aggression scores, compared to people in the other two study groups.
This doesn't mean that patients experiencing sleep problems should take themselves off Zocor or another statin, Smith said. "The broader benefit of decreasing heart attack and stroke must be taken into account," he said.
And patients who find themselves truly sleep-deprived can also talk to their doctor about finding an alternate statin, he said.
Visit the National Sleep Foundation for more on sleep disorders.
SOURCES: Beatrice Golomb, M.D., Ph.D., associate professor, medicine and family and preventive medicine, University of California, San Diego School of Medicine; Sidney Smith, M.D., past president, American Heart Association, and director, Center for Cardiovascular Science and Medicine, University of North Carolina School of Medicine, Chapel Hill; Nov. 7, 2007, presentation, American Heart Association annual meeting, Orlando, Fla.
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