What are the approaches used in drug discovery?

A historical perspective on the drug development process

Target-based drug discovery and phenotype-based drug discovery are the two notable approaches.  There may be others, but they are rarely encountered.

Step 1 – Target identification and Validation

Step 2 – Hit identification and Validation

Step 3 – Moving from a hit to a lead

Step 4 – Lead Optimization

Step 5 – Late Lead Optimization

According to the Lilly study¹ one stage of clinical trials that stands out as particularly troublesome for drug candidates is phase II.  The failure rate for compounds advanced into phase II is a staggering 66%.  Phase II is the stage in which an IND’s efficacy in humans is first confirmed.  Failure in phase II is, therefore, most closely aligned with efficacy problems, although safety and economic problems can also appear during phase II.

References

1. https://www.lilly.com/