10. Drug development and approval In vitro studies Preclinical testing Animal testing Clinical trials Average years 1 to 5 years 2 to 10 years 1 year IND NDA Post-marketing surveillance (Phase 4) Phase 1 – normal volunteers: safety, pharmacokinetics Phase 2 – selected patients: therapeutic efficacy, dose range Phase 3 – large populations of selected patients: therapeutic efficacy, safety in double blind studies Long-term toxicity studies