This article’s aim is to understand if and how the efforts to accumulate and organize clinical data transformed the regulation of pharmaceutical care. The authors analyze how the employment of databases by collectives of physicians and researchers shape both clinical and policy practice—and thereby reshape the relation between clinical work and policy. Since the late 1990s, Dutch government has supported the development of clinical databases for specific expensive medicines to gain oversight about actual medicine use. To be able to produce evidence for appropriate medicine use, the collectives set regulations in clinical practice. These internal regulations provide a framework for establishing “appropriate medicine use”, steering reimbursement decisions. However, internal regulation and policy rules differ in how quickly they can change. While the employment of databases in clinical practices results in a constant adjustment of the protocols, policy makers require the databases to provide for static moments of “proven appropriate medicine use” in order to account for and define a fixed and closed formulary. Subsequently, the employment of the databases did not deliver on the promise of oversight and control due to different clinical and policy requirements. Nevertheless, the databases did stimulate appropriate medicine use and reimbursement in clinical practice.