In a study conducted in Florida, researchers found that drugstores in the poorest areas charge more, on average, for four widely used prescription medications than do pharmacies in wealthier neighborhoods.
Fortunately for patients who are uninsured but able to shop around, every ZIP code does include pharmacies that charge less for these drugs, the study team found.
"If it's a medication you're going to be on for a while it's probably worth making a few phone calls," Dr. Walid F. Gellad of the University of Pittsburgh School of Medicine and RAND Corporation told Reuters Health. Gellad conducted the research while at Brigham and Women's Hospital in Boston.
Florida pharmacies that fill prescriptions for Medicaid patients are required by law to post their prices for the 100 most commonly used medications on a Web site, MyFloridarx.com.
Using this Web site, Gellad and colleagues looked at data for November 2006 on the ulcer drug Nexium, the asthma drug Advair, the heart drug Plavix, and the antibiotic azithromycin, specifically the "Z-Pak" formulation. They then categorized all of Florida's 627 ZIP codes into four groups based on median income.
Across the board, the researchers found, the four drugs were priced highest in the poorest ZIP codes, averaging 9 percent more than the average for the state.
Independent pharmacies charged an average of 15 percent more for each of the drugs than the statewide average, but there was little geographic variation in the prices chain drugstores charged.
Drug stores in ZIP codes with median incomes below $20,000, for example, charged $176 for a month's supply of Nexium, $213 for Advair, $163 for Plavix, and $55 for a Z-Pak, compared to $160, $198, $149, and $50, respectively, at pharmacies in ZIP codes where median income was greater than $60,000.
"Even small increases in drug prices can dramatically affect medication adherence among the poor," the researchers note in their report.
While the higher costs in poorer neighborhoods were largely driven by higher prices at independent drugstores, they point out, every ZIP code also had independent pharmacies that charged about the same as did chain drug stores.
But people living in poorer areas may have a tougher time shopping around, the researchers add, given limitations in health literacy, difficulty finding transportation, and other factors.
There are options available for people without health insurance to cut down on their out-of-pocket medication costs, Gellad noted, such as programs run by the pharmaceutical industry and by individual states.
Given that other states, including New York, Michigan and Minnesota, also have online drug price databases, "it would be interesting to see if these kinds of issues of geographic variation in price are present in those areas as well," Gellad said.