their toxicity. This decision came 4 years after failed attempts in the United States to achieve OTC status for low-dose statins (Mitka, 2004). Against this background, the committee believes the time is right for a major study on the use of OTC drugs and the epidemiology of associated medication errors and ADEs, as well as drug–drug and drug–disease interactions.

An emerging literature suggests that complementary and alternative medications have the potential for adverse interactions with prescription drugs (D’Arcy, 1993; Calis and Young, 2004). The Institute of Medicine’s (IOM) recent report Complementary and Alternative Medicine (IOM, 2005) recommended that the National Institutes of Health and other public agencies provide the support necessary to develop and implement a sentinel surveillance system (comprising selected sites collecting and reporting data on patterns of use of these and conventional medications), practice-based research networks,¹ and complementary and alternative medication research centers to facilitate the work of the networks (by collecting and analyzing information from national surveys, identifying important questions, designing studies, coordinating data collection and analysis, and providing training in research and other areas). The IOM report also recommended that the National Institutes of Health and other public or private agencies sponsor quantitative and qualitative research to examine adverse events associated with complementary and alternative medications and their interactions with conventional treatments. The committee endorses both of these recommendations.

There have been few micro-level studies of the costs of medication errors. Most of these studies have estimated either the extra hospital costs of an ADE occurring while the patient is in the hospital or the costs of hospital admissions attributable to earlier ADEs. Two of these studies are now quite dated: one used data from 1990–1993 (Classen et al., 1997) and the other data from 1993 (Bates et al., 1997). Apart from one study relating to ambulatory care (Field et al., 2005), all of the studies related to hospital care. Clearly there are large gaps in our understanding of the costs of