This Guidelines applies to studies of post-marketing changes to chemical drug substances and chemical drug products and is for reference by drug marketing authorization holders/drug substance registrants in studies of changes. 

Depending on risks of influence of changes on the safety, effectiveness and quality controllability of drugs, changes mentioned in this Guidelines are classified into three categories: major changes, moderate changes and minor changes. Changes that are highly likely to have an impact on drug safety, effectiveness, and quality controllability are referred to as major changes; changes that are moderately likely to have an impact on drug safety, effectiveness, and quality controllability are referred to as moderate changes; changes that are minimally likely to have an impact on drug safety, effectiveness, and quality controllability are referred to as minor changes.