Responsiveness to physicians' requests for information concerning drug interactions: a comparison of brand and generic companies.

Research-based pharmaceutical companies maintain that there are important differences between themselves and their generic competitors. Prominent among them is an alleged greater ability to provide accurate and rapid responses to requests from physicians for information about drug products. This study evaluates pharmaceutical company behavior with regard to these issues. Two drug-drug interactions were identified, along with all of the companies in Canada marketing any of the four drugs involved. Each company received a letter describing symptoms suggestive of an interaction in a patient taking its particular product and the relevant second drug. The companies were asked if they were aware of any evidence of an interaction involving the two drugs. They were also asked to provide references regarding the interaction. Responses were received from all companies contacted except one. There were no significant differences (in the hypothesized direction) between the generic and brand companies with regard to either the accuracy or promptness of the response, or the usefulness of the references cited. On the contrary, generic firms were markedly quicker to respond than were brand manufacturers. The latter were slightly more likely to acknowledge evidence of an adverse drug interaction, and to provide useful references to relevant published research.