The objective of this chapter is to guide compounders in the compounding of investigational preparations and placebos that are used in investigational studies, specifically Phase I studies for humans. For the purpose of this chapter, the terms “study” or “studies” are used to refer to investigational studies, specifically Phase I investigational studies or trials. When compounding a preparation, the standards in Pharmaceutical Compounding—Nonsterile Preparations 〈795〉, Pharmaceutical Compounding—Sterile Preparations 〈797〉, and Hazardous Drugs—Handling in Healthcare Settings 〈800〉 apply. In addition to these standards, this chapter applies when a compounder is preparing an agent for use as an investigational agent in a Phase I clinical study.