UK clinical trials reform: what SI 2025/538 changes for sponsors from 28 April 2026
From 28 April 2026, classify notifiable trials with a recorded rationale and track the two dates that drive registration.
In Short
- In force 28 April 2026.
- Register by first participant or 90 days.
- Results summary within 12 months.
The UK has amended the Medicines for Human Use (Clinical Trials) Regulations 2004. The amending instrument, SI 2025/538, was made on 28 April 2025 and comes into force 12 months after that date. This guide summarises provisions read in the instrument as made: commencement and extent, the notifiable trial definition, the sponsor statement route and transparency duties. MHRA guidance, the schedules in full, safety reporting detail and the revised (consolidated) 2004 regulations were not reviewed. It is orientation, not legal advice. Sources checked 5 Oct 2026.
What changed and when
SI 2025/538 amends the 2004 regulations rather than replacing them. Regulation 1 says it comes into force 12 months after the day it was made, and it was made on 28 April 2025, so the changes apply from 28 April 2026.
More on what changed and when
It extends to England and Wales, Scotland and Northern Ireland. The instrument also changes terminology, for example defining participant in place of subject, so procedures, templates and training that quote the old wording will need review under change control rather than a one-off edit.
Notifiable Trials
New regulation 11A defines a notifiable trial. It must have no significant safety concerns with any investigational medicinal product, as far as the sponsor is aware having made reasonable enquiries; it must meet Condition A, B or C; and it must not involve participants who are under 18, pregnant or breastfeeding, or certain categories of investigational medicinal product listed in the regulation.
Notifiable trial screen (regulation 11A)
More on notifiable Trials
Where a request for approval contains a statement confirming the trial is notifiable, the licensing authority may, if it considers it appropriate, rely on that statement without further assessment. Read Conditions A to C in full before you classify a trial.
Registration and Results
Under the transparency provisions, the sponsor must register a trial in a public registry by the earlier of the date the first participant is recruited and 90 days after approval. Within 12 months beginning the day after the trial concludes, the sponsor must publish a summary of results in the same registry and offer all relevant persons a summary written for lay readers.
Worked Example: Transparency Dates for Trial CT-UK-0142
- Day 0Trial approvedLicensing authority
- Day 41First participant recruited: registration due now (earlier date)Sponsor
- ConclusionTrial concludes; 12-month clock starts next daySponsor
- Within 12 monthsResults summary in registry; lay summary offeredSponsor
More on registration and Results
The sponsor may apply for a deferral or waiver, at the time of the approval request or later. Each of these duties is subject to the exceptions listed in the regulation.
Modifications
The amended regulations describe substantial modifications as Route A or Route B, and set conditions under which some changes, such as certain investigator's brochure updates, are handled differently. The routes are defined in the instrument and should be read in full before your team classifies a change.
More on modifications
A practical step is to make the classification itself a recorded decision: who assessed the change, which route applies, why, and what was submitted, so the trial master file shows the reasoning as well as the outcome.
Getting Procedures and Records Ready
Most of the work is in procedures and evidence: a classification step for notifiable trials with its rationale, a registry tracker with the two dates that drive registration, a results-summary plan that starts at trial conclusion, updated terminology in templates, and training records showing staff read the revised procedures. Named people in your organisation make each regulatory decision.
Procedure updates (invented sponsor SOP set)
| Procedure | Change | Evidence |
|---|---|---|
| Trial classification | Add notifiable trial step | Signed rationale per trial |
| Registry | Track approval and first-participant dates | Registry tracker |
| Templates | 'Participant' terminology | Change record and training |
- Trial classification
- Change
- Add notifiable trial step
- Evidence
- Signed rationale per trial
- Registry
- Change
- Track approval and first-participant dates
- Evidence
- Registry tracker
- Templates
- Change
- 'Participant' terminology
- Evidence
- Change record and training
More on getting Procedures and Records Ready
This guide did not review MHRA guidance or the Schedules in detail, so check those before finalising your procedures.
Questions
When do the amended UK clinical trials regulations apply?
SI 2025/538 was made on 28 April 2025 and comes into force 12 months after that day, so from 28 April 2026.
Do the changes apply in Northern Ireland?
Yes. Regulation 1(3) says the instrument extends to England and Wales, Scotland and Northern Ireland.
How quickly must a UK trial be registered?
By the earlier of the date the first participant is recruited and 90 days after approval, subject to the exceptions and the deferral or waiver route in the regulation.
Does V5 submit applications or run trials?
No. V5 keeps controlled procedures, training records, deviations and change records. Your sponsor team classifies trials and makes every submission.
Practical orientation, not legal advice. Rules differ by jurisdiction; your quality and compliance team decides what applies.
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