Understanding and documentation of drug-drug interactions (DDIs) are an important component of drug development, and of clinical therapeutics. Because clinical DDI studies are costly, time-consuming, and involve some risk, not all clinical DDI questions can be realistically addressed through human DDI trials. In vitro models have been used to identify and predict drug combinations that might interact, and combinations that are unlikely to interact. This screening or "filtration" information allows clinical resources to be targeted in a more informed way. Still, many DDI studies will end up with a negative result. Negative DDI results constitute important and clinically relevant information, and scientific reports of such studies are candidates for publication.