In medicine, biotechnology and pharmacology, drug discovery is the process by which drugs are discovered and/or designed The process of drug discovery involves the identification of candidates, synthesis, characterization, screening, and assays for therapeutic efficacy.

Targeted drug delivery system is a special form of drug delivery system where the medicament is selectively targeted or delivered only to its site of action or absorption and not to the non-target organs or tissues or cells. To the specific type of cell (or) even an intracellular region.