药物开发公司或团体引入临床前检测的新的待选药物分子。尽管通常制药工业只在决定NCEs产生的数量时，只对小有机分子中（传统药物）计数，NCEs也可以包括基因或基因片段，蛋白或多肽，或者小分子。制药工业每年产生的NCEs的数量对公司保持发展的能力致关重要。最近人们意识到NCE短缺，希望基因组学、组合化学和高效筛选这些新技术的应用能改变这一不平衡。

New candidate drug molecules that are advanced into preclinical testing by the research arm of a drug discovery company or organization. NCEs may include genes or gene fragments, proteins or peptides, or small molecules, although typically the pharmaceutical industry has counted only small organic molecules (“classical” drugs) in their determination of the number of NCEs generated. The number of NCEs created by the pharmaceutical industry each year is critical to the ability of companies to maintain growth. An NCE deficit has recently been identified, and it is hoped that the application of new technologies such as genomics, combinatorial chemistry and high-throughput screening will redress the balance.