In Reply: We agree with Dr. Stone that pharmaceutical companies conduct vigorous marketing efforts and that these activities affect physicians' prescribing practices. In our paper, we noted a rapid increase in ziprasidone use among VA patients with schizophrenia in the first years after its market introduction. We attributed the increase to physicians' and patients' eagerness to try a new medication, because many patients with schizophrenia continue to have problematic symptoms despite ongoing treatment. However, as Dr. Stone rightly points out, pharmaceutical marketing efforts may have contributed to physicians' eagerness to try this new drug and the rapid rise in its market share.
However, we note that our study dealt primarily with patterns of dissemination of this new antipsychotic, rather than overall rates of adoption—and most of our observations regarding the patient characteristics associated with earlier ziprasidone use are not easily attributed to pharmaceutical marketing efforts. It may be that physicians' earlier use of ziprasidone among patients with diabetes was a result of their exposure to company materials that promoted the medication's reduced propensity for causing weight gain and metabolic complications, rather than from their own careful review of the literature. It is more difficult, however, to attribute differential use by age and race or ethnicity to drug company influence.
We found that African Americans and older patients were less likely to receive ziprasidone during its first years on the market, with differences in use by race diminishing somewhat over time. To our knowledge, ziprasidone was not marketed as being more efficacious among white or younger patients. Thus, although we agree with Dr. Stone that pharmaceutical marketing may speed adoption of new antipsychotic agents, particularly among subgroups for which there may be plausible clinical reasons for using the drug, we believe that we must look further to explain early differential use of new therapeutics by age and race or ethnicity.
