During clinical trial of drug, ethical clearance is not necessary in which phase?
Phase 4 is post-marketing surveillance where drug ethical clearance is not required. Ref: Guosheng Yin (2012) Chapter 2, Fundamentals of Clinical Trails, Clinical Trial Design: Bayesian and Frequentist Adaptive Methods, Wiley Publications, USA, Page 25 ; Goodman and Gillman, 10th Edition, Page 60
Phase II
Phase I
Phase IV
Phase III