Varying appearance of generic pills may affect medication adherence after MI

Adherence to medications after myocardial infarction (MI) in patients with cardiovascular disease may be affected by variation in pill appearance, according to a new study.

Researchers performed cohort and nested case-control studies using claims from a U.S. commercial health insurance database to examine whether inconsistent appearance of generic medications was associated with inconsistent use in patients with cardiovascular disease after MI. Patients who were hospitalized for an MI and discharged between 2006 and 2011 and started treatment with a generic beta-blocker, angiotensin-converting enzyme (ACE) inhibitor, angiotensin II-receptor blocker (ARB), or statin were included.

Case patients were those who stopped their index medication for at least a month, and control patients were those who continued treatment. The researchers matched control patients to case patients by therapeutic medication class, sex, age, and number of times the drug was dispensed before treatment nonpersistence. Rates of changes in pill color and shape in the year after MI were determined, and the 2 refills preceding nonpersistence were examined to see whether pill color or shape had changed. The study results appear in the July 15 Annals of Internal Medicine.

A total of 11,513 patients began treatment with a generic prescription drug in the class of interest 90 days after hospital discharge for MI. Most of the patients were men with commercial insurance; the average age was 57.7 years. A generic beta-blocker was the most common drug prescribed (75.4% of patients), followed by a generic ACE inhibitor or ARB blocker (52.8%) and a generic statin (40.0%). Change in pill shape or color affected 29% of patients (3,286 of 11,513) during the study. Statins changed appearance most often, and beta-blockers changed appearance least often. There were 4,573 episodes of treatment nonpersistence matched to 19,881 control episodes. Odds of nonpersistence in case-patients increased 34% after a pill color change (adjusted odds ratio, 1.34; 95% CI, 1.12 to 1.59) and 66% after a pill shape change (adjusted odds ratio, 1.66; 95% CI, 1.43 to 1.94).

The authors acknowledged that they examined only 3 categories of drugs prescribed after MI, that they did not evaluate effects on clinical outcomes, and that they had no data on socioeconomic status or enrollment in automatic refill programs. However, they concluded that variation in appearance of generic pills is associated with nonpersistent use after MI in patients with heart disease. “Until the FDA or manufacturers of generic drugs take the initiative to make consistent pill shape or color an industry standard, it is incumbent on prescribers and pharmacists to take steps to warn patients about the diversity of the shapes and colors of the pills containing their generic cardiovascular drugs to reduce the burden of these changes on the public health,” the authors wrote.