Guidance

Route B substantial modification pilot

Clinical trials Route B substantial modifications pilot starts on 1 October 2025. Prepare for the implementation of new regulations from 28 April 2026.

• From: Medicines and Healthcare products Regulatory Agency
• Published: 18 August 2025
• Last updated: 21 January 2026 — See all updates

Documents

Route B substantial modification pilot

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Details

A Route B substantial modification refers to a specific category of changes made to a clinical trial approval under the Medicines for Human Use (Clinical Trials) (Amendment) Regulations 2025.

Published 18 August 2025

Last updated 21 January 2026 + show all updates

1. 21 January 2026

   Updated to fix broken email link

2. 18 August 2025

   First published.