MONDAY, May 5 (HealthDay News) -- Prices of prescription drugs can vary by $100 or more for the same drug from store to store -- and even within the same chain. So it pays to shop around, a new survey found.

But the survey also found that consumers are less likely to consult with pharmacists about the drugs they're using than they were in the past, which can lead to serious consequences in terms of drug interactions.

"More people are paying a higher percentage of out-of-pocket expenses for their prescriptions than they did in 2002," said Tod Marks, senior editor at Consumer Reports magazine, which conducted the survey.

"In our survey, we found that there was a significant price difference, not only for the same drug at different stores, but there were price differences within the same chain and the online price," Marks said. "Sometimes those prices can be significantly different."

The findings were published in the June issue of Consumer Reports.

For the survey, the magazine called 163 pharmacies nationwide to determine price differences for four prescription drugs -- three name brand medicines and one generic.

The price for a three-month supply of the urinary incontinence drug Detrol ranged from $365 to $551. The price for Plavix, a drug that prevents blood clots, ranged from $382 to $541. Prices for Levoxyl, a treatment for hypothyroidism, varied from $29 to $85. And the costs for the generic osteoporosis drug alendronate ranged from $124 to $306, the survey found.

Costco was the cheapest source for the four drugs, while Walgreens and Rite-Aid were among the most expensive, according to the survey.

The survey also found that consumers shouldn't rule out independent drug stores -- while they may not be the cheapest, their prices are competitive, and they offer top service.

"A lot of people have the assumption that independent drug stores are expensive," Marks said. "In many cases, they were not the cheapest overall, but we did find a significant number of mom-and-pops that were highly competitive."

Consumers should also ask their employers about pharmacy benefit managers (PBMs), which can offer substantially lower prices and co-payments, Marks said.

Marks also recommended buying generic drugs because they can cost up to 50 percent less than their brand-name equivalents. And consumers should look for store discount programs that can lower the cost of prescription medications for those without drug insurance, he said.

In another part of the survey, Consumer Reports questioned 40,133 readers about their drugstore experiences. Among the findings: People asked pharmacists for advice on prescription drugs just 38 percent of the time.

That's down from 50 percent since the last survey in 2002, Marks said, adding, "That's a pretty significant shift in the consumer-pharmacist relationship."

That's a worrisome trend, Marks said, because one-third of U.S. adults take five or more prescription medicines or supplements. And some 18 million people end up in hospital emergency room's each year because of medication errors, he said.

"Consumers should consult with their pharmacists, whether they're taking prescription drugs or even over-the-counter stuff, because people think they're innocent, but the fact of the matter is they can have serious ramifications," he said.

Marks noted that independent and chain drug stores both ranked high in consumer approval. Independent local pharmacies often ranked higher in personal service, compared with chain pharmacies, where consumers often experience longer waits, he said.

Pharmacies within supermarkets were rated high for convenience, Marks said. "One of the nice things about supermarket pharmacies is that they tend not to be as crowded as the big chains," he said.

Among mass-market retailers, Kmart and Shopko came out on top in terms of drug prices, Marks said. Wal-Mart and Target got high ratings for offering cheap generic drugs, he said.

A representative of the pharmacy industry said the reasons for the price variance between stores are likely to be complex.

"In any market, there is a price variation," said Chrissy Kopple, vice president of media relations at the National Association of Chain Drug Stores, based in Alexandria, Va. "As a trade association, we cannot comment in great detail on prescription drug pricing due to anti-trust issues. However as is the case with any business, many factors play roles in pricing decisions, including costs, business strategy and local competition," she said.

More information

For more on comparing drug prices, visit Consumer Reports.