(CNN) -- It's not the color, but what's inside that counts when it comes to medication. However, doctors suspect that's not exactly how patients see it.
According to a study published Monday in the medical journal Archives of Internal Medicine, changes in pill color significantly increase the odds that a patient will fail to take their medication as prescribed by their doctor.
First, the basics
Generic drugs are approved by the U.S. Food & Drug Administration's Office of Generic Drugs. These off-brand alternatives must be "bioequivalent" to the brand-name version, meaning they must be identical in terms of dosage form, strength, route of administration, quality, intended use, and clinical efficacy. But the FDA does not require that the two versions look alike.
Generics are big business worldwide. In America, they account for more than 70% of prescriptions dispensed, but only 16% of spending. Generic prescriptions are expected to increase even more, as top-selling brand-name medications reach the end of their market - and profit - exclusivity and go "off patent." In the United States, drug patents offer 20 years of protection for the pharmaceutical company, but they are applied for before clinical trials begin, so the effective life of a drug patent tends to be somewhere around 7-12 years.
Dr. Aaron Kesselheim, assistant professor of medicine at Brigham and Women's Hospital in Boston, wanted to investigate whether switching between brand-name and different generic versions of a drug could lead patients to neglect refilling their prescriptions.
"An estimated 50-75% of patients do not take their medications as prescribed," says Kesselheim. When patients don't adhere to prescribed drug regimens, it can can have serious medical, financial, and social consequences. Kesselheim chose to study antiepileptic drugs, due to the fact that epilepsy is a common disease affecting up to 2% of the general population. Additionally, these types of drugs are prescribed off-label for psychiatric disease, chronic pain and other conditions.
Kesselheim and his team analyzed national data gathered between 2001 and 2006, and subsequently split patients into two groups: those who became "nonpersistent" (defined, in this study, as a failure to fill a prescription within five days of the elapsed days supplied) and those who exhibited no delay in refilling. The groups were further matched by age, sex, number of refills and the presence of a seizure disorder diagnosis.
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.
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."
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.