The researchers looked at 11 472 patients who were not persistent in filling their prescriptions for antiepileptic medication and a control group of 50 050 who did not delay in refilling prescriptions. There were both brand-name and generic versions of each of 7 different antiepileptic drugs, which presented an array of 37 colors and 4 shapes. The researchers found that after a minimum of 3 dispensings, 1.20% of these patients had been given pills that differed in color from the prior prescription. The odds of a color change occurring immediately before a filling gap was 27% greater for those who were not persistent in refilling their prescriptions compared with the control group.
The findings have implications for those taking generic medications, which currently account for more than 70% of prescriptions dispensed in the United States. Generic drugs must be comparable with name-brand versions with respect to dosage form, strength, route of administration, quality, intended use, and clinical efficacy. But the color or shape of the generics doesn’t have to be consistent with that of their brand-name counterparts or with that of the other generic versions of the same medication.
“Pill appearance has long been suspected to be linked to medication adherence, yet this is the first empirical analysis that we know of that directly links pills’ physical characteristics to patients’ adherence behavior,” said the study’s principal investigator, Aaron S. Kesselheim, MD, JD, MPH, and an assistant professor of medicine in the division of pharmacoepidemiology and pharmacoeconomics at Brigham and Women’s Hospital in Boston, in a release. “We found that changes in pill color significantly increase the odds that patients will stop taking their drugs as prescribed,” said Kesselheim.
Kesselheim and colleagues suggested that the US Food and Drug Administration (FDA), which approves generic medications, reconsider its current regulatory policy of not requiring that bioequivalent drugs resemble each other.
The findings also offer take-home messages for patients, physicians, and pharmacists, Kesselheim said. “Patients should be aware that their pills may change color and shape, but that even differently appearing generic drugs are approved by the FDA as being bioequivalent to their brand-name counterparts and are safe to take. Physicians should be aware that changes in pill appearance might explain their patients’ nonadherence. Finally, pharmacists should make a point to tell patients about the change in color and shape when they change generic suppliers.”