Researchers found when patients with epilepsy refilled their prescriptions and received a different color pill than they were used to, they were 53% more likely to take a break from taking their drugs as prescribed. Twenty-seven percent of patients taking antiepileptic drugs for other reasons also took a break from their prescribed drug regimen. "Someone who knows it's so important they take their medication to avoid a seizure is much more in tune with color... and (becomes) more stressed out with any potential switch," says Kesselheim.

Conclusion

Patients and caregivers frequently remove pills from their original bottles to organize them in daily pill planners. "Visual cues thus become paramount to identification of pills," says Kesselheim. Therefore, changes in appearance may be jarring or confusing, leading patients to delay pill-taking while seeking validation from a physician, pharmacist, or other health care provider.

Perhaps even more interesting, a pill's physical attributes have been linked to expectations of efficacy of both placebos and prescription drugs. Kesselheim says, "changes in appearance may not only deprive patients of these expectations of efficacy, but potentially even have the opposite effect." It's something that's called the "nocebo" effect, a belief that the newly-substituted pill will be less effective than the previous dose.

Lastly, it's important to note that a filled prescription does not necessarily indicate that the patient actually took his or her medication, and vice-versa. Additionally, says Kesselheim, "what we observed as nonpersistence may have been physician-directed changes in medication dosing frequency."

What's next

As more widely used brand-name drugs face generic competition, the study's authors suggest physicians warn their patients about the possibility of a change in pill color, and that pharmacists take greater care to alert patients when changes in suppliers might lead to new pill characteristics.

In the United States, the FDA has recently started rejecting generic drugs that are larger in size than their brand-name counterparts, citing safety and efficacy concerns, such as increased risk of choking and patient dissatisfaction.

"Based on our results," says Kesselheim, "the FDA would be justified in taking a similar posture about new generic drugs that differ in color."

"At a minimum," Kesselheim says, "our results should clarify that manufacturers cannot protect their drugs' physical characteristics through the principle of 'trade dress,'" - physical attributes such as color, shape, size, texture, aroma, and flavor. By definition, trade dress attributes legally cannot affect the impact of a drug on a consumer. But this study concludes that's exactly what's happening.