Free drug samples that doctors give to patients may save them money in the short term, but it costs more for long prescriptions, a study said.

That's because patients are more likely to end up paying for a brand-name-only drug, said researcher Dr. David P. Miller of Wake Forest Baptist.

Researchers used a pharmacy database to track all of the prescriptions for several kinds of chronic medication, including those for blood pressure, diabetes, acid reflux and pain. The study followed a clinic both when it kept free samples in a closet and after it had closed.

Uninsured patients were given generic drugs 12 percent of the time when free samples were available and 30 perecnt of the time when they weren't. There was no significant change for Medicaid patients.

Samples are usually only available for brand-name drugs that have marketing money behind them.

"The theory is that drug companies hand out samples because it gets physicians in the habit of using a drug and physicians, therefore, are more likely to prescribe that drug later," Miller said.

Medicaid patients were generally prescribed generic drugs, even with the availability of branded samples. At the time of the study, all drugs for Medicaid patients were only $1.

The complete findings can be found in the September issue of Southern Medical Journal.