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Confusion About Multiple Drug Dosing

Standardizing dose times will help patients take drugs safely

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February 28, 2011 | by Marla Paul

CHICAGO --- Many older patients, who take an average of seven medicines a day, are so confused by the vague instructions on prescription bottles that they don’t realize they can combine their medications to take them more efficiently. A new Northwestern Medicine study shows patients thought they had to take seven medicines at least seven and up to 14 separate times a day.

“A complex and confusing regimen means people are less likely to take their drugs properly, and that means they are not getting the full benefits of their medicine,” said Michael Wolf, associate professor of medicine and of learning sciences at Northwestern University Feinberg School of Medicine. He is lead author of the study, funded by the National Institute on Aging, that will be published Feb. 28 in Archives of Internal Medicine.

Wolf and colleagues have proposed a universal medication schedule that standardizes medicine prescriptions into doses at four clearly identified periods of day – morning, noon, evening and bedtime (instead of twice daily or every eight hours.)

“Standardizing the times to take medicine will help patients safely take their medicine, make their lives easier and improve their health outcomes,” Wolf said. He was on the panel of the U.S. Pharmacopeia that recently released guidance for drug labeling praising the four daily doses approach.

For the study, Wolf and colleagues interviewed 464 patients, with an average age of 63, at an academic general medicine practice and three federally qualified health centers in Chicago to see how patients would schedule a typical seven-drug regimen. The majority of participants were well educated, but nearly half had low or marginal health literacy skills.

Wolf found people overcomplicate the dosing schedule of prescription drugs. Even if two drugs were prescribed in the same manner (one pill twice daily), nearly a third of patients (30.8 percent) would not take them together. When two drugs could have been taken together but doctor instructions were written differently (one pill twice daily versus one pill every 12 hours) 79 percent of patients would not consolidate these medicines and take them at the same time. If instructions for two drugs were the same with the only exception that one said “with food and water,” half the patients would not take the two drugs at the same time.

Low health literacy was the greatest predictor of patients dosing their medications a greater number of times per day.