通过优化药用减少毒性和副作用可以使其转变为一种新药的化合物。一旦通过基因组学和药理学方法发现和证实了一个有用的治疗靶子，识别先导化合物是新药开发的第一步。一般的，很多潜在化合物被筛选，大量紧密结合物被识别。这些化合物然后经过一轮又一轮地增加严格性的筛选来决定它们是否适合于先导药物优化。一旦掌握了很多先导物，接下来就进入优化阶段，这需要做三件事：应用药物化学提高先导物对靶子的专一性；优化化合物的药物动力性能和生物可利用率；在动物身上进行化合物的临床前的试验。

A compound that could potentially be converted to a new drug by optimizing its beneficial effects and minimizing its toxicity and side effects. Identifying lead compounds (typically by high-throughput screening) is the first step in the drug discovery process once a useful therapeutic target has been identified and validated through genomics and pharmacology. Typically, many potential compounds are screened (the “primary” screen) and numerous tight-binders (“hits”) are identified. These compounds are then taken through successive rounds of screening (“secondary” screens) of increasing stringency in order to determine their suitability for “lead optimization.” Once a handful of leads have been identified in this way, they are taken into “lead optimization”, which entails three things; the application of medicinal chemistry to improve the hit’s specificity to the target, optimization of the compound’s pharmacokinetics and bioavailability (ability to be metabolized by the body and to travel to its designated receptors in the afflicted cells and tissues), and the testing the compound in pre-clinical studies in animals.