Investigator's Brochure (IB): E6(R3) Checklist

The Investigator’s Brochure (IB) is the sponsor-produced compilation of nonclinical and clinical data on an investigational product that every investigator, site, and reviewing IRB/IEC must hold before a trial starts and throughout its conduct. ICH E6(R3) Good Clinical Practice — finalized at ICH Step 4 on 6 January 2025 and now the current core GCP guideline — sets out the IB’s required contents in Appendix A, replacing the Section 7 treatment used in the earlier E6(R2) addendum. This guide is a working checklist built directly against the E6(R3) text: what the IB must contain, who authors and approves it, why its Reference Safety Information (RSI) subsection is the single most consequential part of the document, when a full IB isn’t required at all, and how updates are supposed to flow to sites and IRBs/IECs while a trial is running. For the formal definition, see the Investigator’s Brochure (IB) dictionary entry.

What the IB is for

Per ICH E6(R3) Appendix A.1, the IB exists to give investigators and other trial staff the information they need to understand — and comply with — key protocol features such as dose, dosing interval, route of administration, and safety monitoring. It is the document a clinician uses to make an independent, unbiased risk-benefit judgment about the trial, which is why the guideline requires it to be written in a “concise, simple, objective, balanced and non-promotional form.” It is distinct from the protocol (how the trial is run) and the informed consent form (written for participants) — the IB is the risk-benefit reference for investigators and reviewers.

IB contents checklist (ICH E6(R3) Appendix A)

E6(R3) does not prescribe a rigid template, but Appendix A specifies the minimum information an IB should contain, and roughly the order it should appear in. Use this table as a completeness check against a draft IB or one delivered by a CRO.

Section (E6(R3) ref.)	What it contains	Why it matters to the investigator
Title page (A.2.1)	Sponsor’s name, identity of the investigational product (research number, chemical/generic name, and trade name where used), release date; suggested: edition number, the edition it supersedes, and the data cut-off date	Establishes exactly which version is in force at the site
Confidentiality statement (A.2.2)	Instruction to treat the IB as confidential, for the sole use of the investigator/institution, site staff, regulators, and the IRB/IEC	Sets handling expectations for proprietary data
Table of contents (A.3.1)	Navigation for the full document	Lets reviewers and IRB/IEC members find the relevant section quickly
Summary (A.3.2)	A brief (preferably ≤2-page) overview of the significant physical, chemical, pharmaceutical, pharmacological, toxicological, pharmacokinetic, metabolic, and clinical information relevant to the current stage of development	Fast risk-benefit orientation before the full detail
Introduction (A.3.3)	Chemical/generic/trade name, active ingredients, pharmacological class and expected position within it, rationale for the research, and anticipated indication(s)	Frames why this product is being studied
Physical, chemical & pharmaceutical properties and formulation (A.3.4)	Description of the substance(s), structural formula, formulation and excipients, storage/handling instructions, and any structural similarity to known compounds	Informs storage, handling, and dispensing procedures at the site
Nonclinical studies (A.3.5)	Pharmacology, pharmacokinetics/metabolism, and toxicology data from animal or in vitro studies — species, dose, route, duration, and results — with enough detail to judge relevance to humans	Basis for dose selection and for identifying species-specific findings relevant to human risk
Effects in humans (A.3.6)	Pharmacokinetics/metabolism, safety, efficacy, and dose-response findings from prior human studies, plus marketing experience where the product is already marketed elsewhere	Direct evidence of how the product behaves in people, including known adverse drug reactions
Summary of data and guidance (A.3.7)	An integrated discussion of the nonclinical and clinical data, with practical guidance on anticipated adverse reactions, safety monitoring, and management of overdose	The section investigators use most directly for day-to-day trial-conduct decisions

Each section should carry its own literature references where appropriate, and tabular formats are preferred for the nonclinical and clinical data summaries — E6(R3) calls this out explicitly to keep dense data legible.

Reference Safety Information (RSI): the section that matters most

Buried inside Appendix A.1.2 is the subsection that does the most operational work in the entire document. The Reference Safety Information (RSI) is the IB’s cumulative list of adverse reactions already known or expected for the investigational product, including their frequency and nature. Every time a serious adverse event is reported during the trial, the RSI is the yardstick used to determine expectedness: if the event isn’t consistent with what the RSI describes, it’s classified as unexpected, which is what makes it a potential SUSAR requiring expedited safety reporting under E6(R3) Section 3.13.2(c) rather than routine periodic reporting.

This has a direct practical consequence: an IB whose RSI is stale — missing a recently confirmed drug-related SAE, or not yet reflecting a nonclinical toxicology signal — can misclassify genuinely expected events as unexpected (generating reporting noise) or, worse, misclassify a genuinely new signal as already-expected (suppressing a report that should have gone out). Keeping the RSI current is therefore not a documentation nicety; it is the mechanism that keeps a trial’s expedited safety-reporting obligations accurate. This is also why an outdated IB is a recurring finding in sponsor and site GCP inspections — see our companion guide on adverse event reporting to the IRB for how expectedness determinations feed into what a site must report and when.

Who authors and approves the IB

Under E6(R3) Appendix A.1.1, the sponsor is generally responsible for ensuring an up-to-date IB is developed and, per Section 3.7.2, for providing it to each potential investigator/institution with sufficient time for review before the trial starts. Two authorship rules from the guideline are easy to miss:

A medically qualified person must be involved in generating the IB, but its contents should be approved by the disciplines that actually produced the underlying data (nonclinical, clinical, CMC, and so on) — authorship is cross-functional, not a single sign-off.
In an investigator-initiated trial, the sponsor-investigator must determine whether a brochure is already available from the product’s license/marketing-authorization holder; if the sponsor-investigator is supplying the investigational product themselves, they must provide the necessary product information to site staff directly.

This work is frequently delegated to a contract research organization under a written transfer of duties — see Sponsor vs. CRO for how that delegation typically splits — but the sponsor retains ultimate accountability for IB content and currency regardless of who drafts it.

When a full IB is not required

This is one of the most common real-world questions, and E6(R3) answers it directly in Appendix A.1.1: where permitted by the applicable regulatory authority, current scientific information such as a basic product information brochure — a Summary of Product Characteristics (SmPC), package leaflet, or approved labelling — may substitute for a full IB, provided it includes current, comprehensive, and detailed information on every aspect of the investigational product that could matter to the investigator. In the US, 21 CFR 312.23(a)(5) frames this the same way: an IB is required “if required under §312.55,” which in turn only obligates the sponsor to furnish an IB containing the §312.23(a)(5) information — for an approved product used within its labeling, the FDA-approved labeling itself typically fills that role instead.

The substitution has a limit: if an already-authorized medicinal product is being studied for a new indication, a new IB specific to that use should be prepared, unless the sponsor has a documented rationale for using a single IB across uses. A change in population, dose, or route of administration is treated the same way as a new indication for this purpose — it isn’t automatically covered by the existing marketed-product labeling.

Annual review and event-driven updates

The IB is not a one-time submission. E6(R3) Appendix A.1.1 sets two update obligations that a study team needs a process for:

Scheduled annual review. The IB should be reviewed at least once a year and revised as necessary under the sponsor’s documented procedures, even absent a specific new finding. More frequent revision is expected depending on the product’s stage of development and how quickly relevant new information is being generated — an early-phase, actively enrolling program should not run on a rigid once-a-year cadence.
Event-driven update. When significant new safety or other relevant information becomes available, the sponsor must produce a revised IB (or a formal update) independent of where the annual cycle stands. E6(R3) is explicit that some information is urgent enough to be communicated directly to investigators — and, where warranted, to IRBs/IECs and regulators — before it has been folded into a formally revised IB edition; waiting for the next full revision is not acceptable when the information is time-sensitive.

The mechanics of either path are the same in practice:

Revise and version. The updated IB (or addendum) carries an incremented edition number, a new release date, and ideally a reference to the edition it supersedes, so every recipient can confirm they hold the current version.
Distribute. The sponsor (or delegated CRO) sends the revised IB or addendum to all participating investigators and sites, and to the reviewing IRBs/IECs and applicable regulatory authorities, consistent with E6(R3) Section 3.13.1’s sponsor safety-review obligations.
File. Sites replace the superseded edition in the Investigator Site File (ISF) with the current one and retain the version history as an essential document.
Reassess. Investigators review the new information against ongoing participants — re-evaluating eligibility, consent, and monitoring where the update materially changes the known risk profile.

Version control and distribution: who at the site holds the current copy

The research-administration angle is straightforward but easy to get wrong under deadline pressure. E6(R3) Section 2.4.3 requires a current copy of the IB (or the substitute basic product information) to be part of the initial submission to the IRB/IEC, and Section 2.4.4 requires the investigator/institution or sponsor to keep the IRB/IEC updated as the trial progresses. In practice:

The investigator/institution is responsible for making sure the reviewing IRB/IEC actually has the current IB edition on file — not just that the sponsor sent it.
The current edition belongs in the site’s Investigator Site File as an essential document, with superseded editions retained (not discarded) as part of the version history the TMF/ISF must be able to reconstruct — see our guide to the Trial Master File and essential documents.
FDA’s parallel expectation that investigators rely on current investigational product information is set out in 21 CFR 312.60.

An inspection finding of “outdated IB in the regulatory binder” is almost always a distribution or filing failure at this step, not a sponsor failure to produce the update in the first place — which is why site staff, not just the sponsor’s regulatory-affairs group, need a defined process for confirming and filing each new edition.

Frequently asked questions

What does “IB” mean in a clinical trial?

“IB” is the Investigator’s Brochure — the sponsor’s compilation of nonclinical and clinical data on an investigational product, supplied to every investigator and the reviewing IRB/IEC under ICH E6(R3) Appendix A. It is distinct from the protocol and the informed consent form: the IB is the risk-benefit reference document for investigators and reviewers.

What must an Investigator’s Brochure contain?

At minimum, under E6(R3) Appendix A: a title page with edition and release date, a confidentiality statement, a table of contents, a summary, an introduction, physical/chemical/pharmaceutical properties and formulation, nonclinical study data, effects in humans (including marketing experience where applicable), and a summary of data with practical guidance for the investigator. See the checklist table above for what each section covers.

What is Reference Safety Information (RSI), and why does it matter so much?

The RSI is the IB’s cumulative list of known/expected adverse reactions, with frequency and nature. It’s the reference point used to decide whether a reported serious adverse event is “expected” or “unexpected” — and an unexpected, suspected, serious adverse reaction (a SUSAR) triggers expedited regulatory reporting. A stale RSI can distort that classification in either direction, which is why it’s the single highest-stakes subsection in the document.

How often must the IB be updated?

At least annually as a scheduled review, and additionally whenever significant new safety or other relevant information becomes available — whichever comes first. E6(R3) also expects more frequent revision for actively developing products, and urgent safety information should reach investigators directly rather than waiting for the next formal edition.

Can an approved drug’s label replace the IB?

Yes, where permitted by the regulatory authority — current scientific information such as an SmPC, package leaflet, or approved labelling may substitute for a full IB, provided it is current, comprehensive, and detailed enough to cover everything about the product that could matter to the investigator (E6(R3) Appendix A.1.1; parallel treatment in 21 CFR 312.23(a)(5)/312.55). Studying a new indication, population, dose, or route generally still needs a proper IB or a documented rationale for relying on one IB across uses.

Who prepares and approves the IB — sponsor, CRO, or investigator?

The sponsor is accountable for the IB, though drafting is commonly delegated to a CRO in writing. A medically qualified person must be involved in generating it, and its content is approved by the disciplines that produced the underlying data. Investigators and institutions don’t author the IB, but they must ensure their IRB/IEC and site files hold the current edition.

How is the IB different from an IMPD?

They’re related but distinct. The IB is the ICH E6(R3)-governed document sponsors give investigators and IRBs/IECs to support trial-conduct decisions. The Investigational Medicinal Product Dossier (IMPD) is the EU clinical-trial-application submission to regulators; EU rules permit the sponsor to cross-reference the IB and protocol in the IMPD’s nonclinical/clinical sections rather than duplicating that content.

Did the IB requirements change between ICH E6(R2) and E6(R3)?

The substance is largely continuous, but the structure changed: E6(R2) addressed the IB in Section 7; E6(R3) moved and expanded it into Appendix A, with an explicit new subsection (A.1.2) naming and defining Reference Safety Information, which E6(R2) discussed only implicitly through its safety-reporting text. If your SOPs or training materials still cite “IB — Section 7,” they’re citing the superseded E6(R2) structure.

Investigator’s Brochure: Contents and Updates