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Doctors should more diligently prescribe generic medicines whenever possible, both to help contain rising prescription drug costs and to improve the chances that patients will adhere to their therapies, a top physicians group said Monday.

Generic drugs now account for roughly 88 percent of prescriptions in the United States, even though they amount to less than a third of the more than $325 billion Americans spend each year on prescription drugs. But the American College of Physicians says doctors should be using generics even more often than they already do.

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"While the use of generic drugs has increased over time, clinicians often prescribe more expensive brand-name drugs when equally effective, well proven and less expensive generic versions are available," Wayne J. Riley, president of the American College of Physicians, said in a statement.

Why is that?

Researchers detailed several reasons in a paper published Monday in the group's journal, Annals of Internal Medicine.

One key hurdle is that some patients -- and even some doctors -- perceive lower-cost generic drugs as inferior and associate them with lower effectiveness, despite evidence that most work just as well as their brand-name counterparts. In addition, the report found many physicians still refer to drugs by their original brand name, even long after generic versions become available, which can result in them inadvertently prescribing of more expensive drugs.

Some doctors also reported prescribing brand-name drugs rather than existing generics because a patient requested it. "The likelihood of this behavior was significantly higher for physicians who also reported that they received industry-provided food and samples or who met with [brand name] representatives," wrote the authors, who studied years of past research on the topic.

They said the consequence of such practices likely amounts to billions in lost savings. For instance, they cited a study of Medicare beneficiaries with diabetes, which found that 23 percent to 45 percent of prescriptions, depending on drug class, involved brand-name drugs for which identical generics existed. That rate was far higher than for similar patients treated by the Veterans Affairs system, which has a centrally managed formulary that encourages greater generic-drug use.

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The authors of the new study said relying more on generic drugs, when that is medically appropriate, could do more than save the nation's health system money. They argue that it also might help some patients better adhere to their treatment programs over time.

"Prescriptions for brand-name medications are almost twice as likely as those for generic therapies to be 'abandoned' (that is, never picked up after being filled)," they wrote, citing research from 2010. "Thus, greater use of generic drugs could result in long-term adherence to essential therapies."

The researchers also suggested that providing doctors with free samples of generic drugs for their patients, as well as public awareness or advertising campaigns, might help alter perceptions about generic drugs and increase their usage. But they acknowledged that the effectiveness of such approaches has yet to be evaluated.

The recommendations come at a time when the high cost of prescription drugs has become a topic of national interest. The Obama administration had an all-day gathering on the topic last week, presidential candidates have floated ideas of how to rein in high prices, and a Senate committee plans to hold a hearing on the issue soon.

[Specialty drugs now cost more than the median household income]

A wave of heralded new drugs has arrived on the market in recent years, bringing promising treatments for everything from cystic fibrosis to hepatitis C to certain kinds of cancer. A report published last week found that the average annual retail price of such specialty drugs now exceeds the median U.S. household income. Although patients with insurance do not pay the full cost of drugs, and companies often offer discounts and rebates, the drugs remain exceedingly expensive.

But generic drugs themselves, widely acknowledged as a successful tool in keeping prescription costs in check, have had their own pricing issues. Driven in part by material shortages and industry consolidation, the cost for some generic drugs has spiked.

The authors of Monday's study excluded any evaluation of "biosimilars," which are copycat versions of complex biologic drugs. Only one biosimilar drug has received approval in the United States -- a cancer treatment approved earlier this year -- but the Food and Drug Administration has received a growing number of biosimilar applications.

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