Do free drug samples influence residents' prescribing decisions?

When a pharmaceutical company puts drug samples into the hands of residents as a form of marketing, how does it influence their prescribing behavior? To what extent are treatment decisions based on which samples are available and further, what are the implications for patient care as well as resident education? While this is a frequently debated issue, there has been little objective data describing how drug samples affect resident physicians. In a study published in the August issue of The American Journal of Medicine, researchers from the University of Minnesota and Abbott Northwestern Hospital conducted a randomized study of 29 internal medicine residents over a 6-month period in an inner-city primary care clinic. Highly advertised drugs were matched with drugs commonly used for the same indication that were less expensive, available over-the-counter, or available in generic formulation. By random selection, half of the residents agreed not to use available free drug samples. The authors observed 390 decisions to initiate drug therapy in five drug class pairs.

After selecting drug classes where samples of heavily advertised drugs were provided to the clinic, and where lower priced alternative formulations existed, the authors looked for prescribing differences between physicians who had access to free samples and those who agreed before the study to not use the samples.

There was no contact between pharmaceutical company representatives and residents – all samples were stocked in a cabinet in the clinic – and there was periodic monitoring of the cabinet to ensure that the study drug classes were available.

Richard F. Adair, MD, writes, "We found that resident physicians with access to drug samples in clinic were more likely to write new prescriptions for heavily advertised drugs and less likely to recommend OTC drugs than their peers. There was also a trend toward less use of inexpensive drugs."

Although the study was small and limited to 5 drug classes, the results suggest some potential concerns. Dr. Adair continues, "Access to drug samples influenced prescribing decisions of resident physicians, something that would seem to violate published national guidelines on physician interactions with the pharmaceutical industry. This finding contradicts two widespread beliefs: Drug samples are inherently different from other forms of marketing, and samples help patients manage drug costs in the long term. They raise questions about whether drug samples belong in clinics where residents are learning or low-income patients are receiving care. Other studies have shown that many Americans do not take prescribed medications because they cannot afford them. Whether to provide 'free' samples of expensive drugs to these patients is an ethical dilemma for many doctors."

The study is reported in, "Do drug samples influence resident prescribing behavior? A randomized trial" by Richard F. Adair, MD, and Leah R. Holmgren, MD. It appears in The American Journal of Medicine, Volume 118, Number 8 (August 2005), published by Elsevier.

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