All techniques of drug development, from "trial-and-error" to current rational synthesis, involve animals to test how well medications work and how harmful they are. Every year, millions of animals are killed because of this. After a worldwide discussion over "animal cruelty," several laws were passed and enforced to safeguard animal rights. As a result of these animal protection laws, scientists who study drugs began looking for other ways to do research on animals. This study seeks to consolidate significant non-animal models used for evaluating the safety and effectiveness of medications during preclinical phases.