Modern Approaches to Clinical Trials Using SAS: Classical, Adaptive, and Bayesian Methods

1.1 Introduction

Clinical testing of a drug to support its marketing authorization is often characterized by four phases. Here, we use the word “drug” broadly for a drug or a biologic. Three of the four phases are before the drug is marketed (pre-marketing) and one is afterwards (post-marketing). During the first phase (phase I), researchers investigate what the human body will do to a drug in terms of drug absorption, distribution, metabolism and excretion. The investigation is typically conducted in healthy human volunteers, except for cytotoxic drugs. For cytotoxic drugs, phase I is often conducted in patients with very few therapeutic options due to the anticipated toxicities and uncertainty about a drug’s benefits. When a drug is designed ...