ICH

The problem it solved

Before harmonisation, the same molecule required different studies for different regions — duplicated toxicology, re-run trials, incompatible dossier formats. The cost fell on developers and, through delay, on patients. ICH exists to remove duplication that serves no scientific purpose.

The four series

Series	Domain	Examples
Q	Quality	Q1 stability, Q7 API GMP, Q8-Q11 development, Q9 risk
S	Safety	S1 carcinogenicity, S7 safety pharmacology
E	Efficacy	E6 GCP, E8 study design, E9 statistics
M	Multidisciplinary	M4 the CTD itself, M7 mutagenic impurities

The M series is where the structural pieces sit: M4 defines the Common Technical Document that eCTD implements electronically.

Guidelines, not law

ICH publishes guidelines. They acquire force only when a regional authority adopts them — as FDA guidance, an EU directive or annex, or Japanese notification. In practice adoption is near-universal among members, so the distinction rarely matters commercially, but it matters legally: you comply with your region's implementation, not with ICH.

E6(R3) and why it was rewritten

ICH E6 defines Good Clinical Practice. The R2 revision had been criticised for encouraging procedural box-ticking — monitoring every data point, documenting exhaustively — without improving participant safety or data reliability.

E6(R3) restructures around proportionality and quality by design in trials: identify what genuinely matters to participant safety and result credibility, and concentrate effort there. It also finally accommodates decentralised elements, real-world data sources and modern trial technology that R2 predated.