Historical Signal Evaluation: Metamizole and Agranulocytosis

Introduction

A pharmacovigilance signal does not necessarily begin with the discovery of a previously unknown adverse reaction.

In some cases, the safety concern is already established. The regulatory question instead becomes whether accumulating evidence, continuing reports, changing clinical circumstances or experience with existing risk-minimisation measures indicates that the risk needs to be characterised differently or managed more effectively.

The 2024 European Union review of metamizole-containing medicinal products provides a useful example.

Agranulocytosis was already a known serious adverse reaction associated with metamizole. The European review was initiated in June 2024 at the request of the Finnish medicines authority after cases of agranulocytosis continued to be reported despite recently strengthened risk-minimisation measures in Finland.

The subsequent Article 107i procedure therefore did not amount to the discovery of a new adverse reaction. It was a regulatory reassessment of a known serious risk and, importantly, of whether existing measures were adequate to minimise its serious consequences.

The Pharmacovigilance Risk Assessment Committee (PRAC) reviewed available evidence and recommended changes intended to improve awareness, early recognition and diagnosis of agranulocytosis. The resulting measures included strengthened warnings, contraindications for specified higher-risk populations, removal of recommendations for routine blood-count monitoring and clearer instructions concerning symptoms, immediate investigation and treatment discontinuation.

This case is particularly valuable for pharmacovigilance professionals because the public regulatory record allows the progression from regulatory concern to evidence assessment to product-information change to be examined in considerable detail.

The central question of this historical evaluation is therefore not:

Does metamizole cause agranulocytosis?

That association was already recognised.

The more useful questions are:

• Why was the issue reconsidered?
• What regulatory questions were asked?
• What evidence was considered?
• How was the effectiveness of existing risk-minimisation assessed?
• Why were some measures strengthened while another apparently logical measure, routine blood-count monitoring, was removed?
• How did the regulatory conclusions translate into product-information wording?
• What can a QPPV learn from the case when evaluating a mature safety issue?

Scope and Method of This Historical Evaluation

This article is a retrospective analysis of publicly available evidence.

It is not a reconstruction of the confidential pharmacovigilance information available to the marketing authorisation holders or regulators during the procedure. Publicly available material cannot reproduce every individual case, complete EudraVigilance analyses, unpublished epidemiological analyses, internal benefit-risk assessments or the full deliberative process of PRAC.

The principal regulatory sources used for this evaluation are:

• the EMA metamizole referral page;
• the scientific background published when the procedure was initiated;
• the PRAC list of questions to marketing authorisation holders;
• the PRAC recommendation;
• the PRAC assessment report;
• the CMDh position;
• the agreed product-information amendments;
• the European Commission decision and associated regulatory documentation.

Scientific literature is used to provide context for the evidence base and to illustrate the longstanding nature of the safety concern.

A distinction is maintained between three types of statements:

Regulatory fact

What EMA, PRAC, CMDh or another competent authority explicitly documented.

Published scientific evidence

What peer-reviewed studies or systematic reviews reported.

Analytical interpretation

What can reasonably be inferred from comparing the evidence, regulatory reasoning and resulting product-information changes.

This distinction is particularly important in historical signal evaluation. A later observer should not inadvertently attribute an interpretation to PRAC that is actually the observer's own reconstruction.

The Regulatory Trigger

A Known Risk With Continuing Reports

The 2024 procedure was initiated on 13 June 2024 under Article 107i of Directive 2001/83/EC.

The trigger was the continuing occurrence of agranulocytosis cases despite recently strengthened risk-minimisation measures in Finland.

This is an important distinction.

The trigger was not:

"Agranulocytosis has just been identified as a new adverse reaction."

It was closer to:

"A known serious adverse reaction continues to occur despite risk-minimisation measures; are the existing measures sufficient?"

This changes the analytical framework.

A new signal may initially require assessment of whether an association exists.

A mature safety issue may instead require assessment of:

• the current strength of evidence;
• the magnitude and seriousness of risk;
• the timing of onset;
• risk factors;
• effectiveness of existing risk-minimisation;
• whether the product information accurately characterises the risk;
• whether current measures are capable of preventing serious outcomes;
• whether alternative measures are more likely to be effective.

The metamizole procedure illustrates the second situation.

Regulatory Timeline

The major milestones were:

The procedure concerned nationally authorised metamizole-containing medicinal products and was handled through the PRAC-CMDh regulatory pathway.

The final outcome was not suspension or withdrawal of metamizole-containing medicines across the EU.

PRAC concluded that the benefits of metamizole-containing medicines continued to outweigh their risks, while recommending strengthened measures to minimise the serious consequences of agranulocytosis.

Understanding the Adverse Reaction

Agranulocytosis

Agranulocytosis is characterised by a severe reduction in granulocytes, particularly neutrophils, and can result in serious or fatal infections.

The clinical significance of the reaction is important when evaluating a pharmacovigilance signal.

A rare event may still represent a major safety concern when:

• the clinical consequences are severe;
• onset can be rapid;
• symptoms can initially be non-specific;
• delayed recognition can worsen outcomes;
• the medicine has substantial exposure;
• an effective intervention is available.

This is why signal evaluation cannot be reduced to counting reports.

The clinically meaningful question is not simply how many cases have occurred.

It is also:

What is the probability of a clinically important event, how serious is the outcome, who is at greatest risk, and can the pathway from exposure to serious outcome be interrupted?

The Historical Evidence Base

Epidemiological Evidence

The association between metamizole and agranulocytosis has been investigated for decades.

Published epidemiological studies have produced varying estimates of relative and absolute risk. A systematic review of the literature published through 2014 found that the majority of epidemiological studies evaluating agranulocytosis reported an increased risk associated with metamizole, although estimates varied substantially between studies.

That variability should not automatically be interpreted as evidence that the association itself is inconsistent.

Differences in:

• study populations;
• prescribing patterns;
• exposure intensity;
• outcome definitions;
• ascertainment;
• geographic setting;
• comparator selection;
• background incidence;
• surveillance systems;

can materially affect risk estimates.

A mature pharmacovigilance assessment therefore needs to distinguish:

evidence for an association

from

precision of the estimated absolute risk.

These are not the same question.

Case Reports and Spontaneous Reports

Individual case reports and spontaneous reports are particularly important for rare serious reactions.

They can provide information about:

• clinical presentation;
• time to onset;
• dechallenge;
• rechallenge;
• concomitant medicines;
• underlying disease;
• laboratory findings;
• treatment;
• clinical outcome.

However, spontaneous reports alone generally cannot provide a reliable incidence estimate.

They can nevertheless contribute substantially to signal identification and clinical characterisation.

For a reaction such as agranulocytosis, the combination of a plausible clinical phenotype, repeated reports, temporal relationships and epidemiological evidence provides a much stronger basis for evaluation than any individual source considered in isolation.

Mechanistic Considerations

The biological mechanism of metamizole-associated agranulocytosis has been investigated extensively but is not reducible to one universally established mechanism.

Published work has explored:

• immune-mediated mechanisms;
• drug-dependent antibodies;
• reactive metabolites;
• direct cellular toxicity;
• genetic susceptibility.

The incompleteness of mechanistic understanding is not necessarily inconsistent with a strong regulatory safety conclusion.

Pharmacovigilance decisions generally do not require every mechanistic step to be established before action can be taken.

The relevant question is whether the totality of evidence supports a clinically meaningful risk and whether the risk can be reduced through appropriate intervention.

This distinction matters in signal evaluation.

A mechanism can strengthen causal inference.

But the absence of a completely resolved mechanism does not, by itself, negate an association supported by clinical and epidemiological evidence.

What PRAC Asked Marketing Authorisation Holders

The published PRAC questions are particularly informative because they show the analytical structure of the regulatory evaluation.

Marketing authorisation holders were asked to address the effectiveness of existing risk-minimisation measures and to analyse available safety data from clinical trials and pharmacoepidemiological studies.

The questions specifically addressed:

• magnitude of risk;
• time to onset;
• the role of underlying infections in severity and seriousness;
• possible risk factors, including genetic and other predispositions;
• effectiveness of existing risk-minimisation measures;
• the effect of the risk on the benefit-risk balance for authorised indications;
• proposals for additional measures, including changes to the SmPC and package leaflet.

This is an important methodological point.

The regulator did not simply ask:

"Is metamizole associated with agranulocytosis?"

The assessment framework was broader.

It asked how the risk behaved and whether the existing controls were working.

That distinction is central to mature signal management.

Evidence Question 1: How Large Is the Risk?

Estimating the absolute risk of metamizole-associated agranulocytosis has historically been difficult.

Published studies have reported substantially different incidence estimates.

This is not surprising for a rare event influenced by:

• population;
• prescribing intensity;
• duration and pattern of exposure;
• case ascertainment;
• geographic differences;
• genetic background;
• competing causes of neutropenia;
• healthcare-system characteristics.

For a QPPV, the lesson is important.

A safety evaluation should not force heterogeneous evidence into a single number merely because a single number appears more authoritative.

Instead, the evaluation should ask:

• Are the estimates directionally consistent?
• What populations produced them?
• What definitions were used?
• What biases could influence the estimates?
• Are the differences clinically meaningful?
• Does the uncertainty materially affect the regulatory decision?

Precision should not be confused with certainty.

Evidence Question 2: When Does the Reaction Occur?

One of the important conclusions of the regulatory review was that metamizole-induced agranulocytosis is not dose-dependent and can occur at any time during treatment or shortly after treatment discontinuation.

The final product-information wording explicitly characterises the reaction as idiosyncratic and states that it may occur even after previous uncomplicated use.

This has an important risk-communication consequence.

If a patient or healthcare professional believes that risk occurs only:

• at high doses;
• after prolonged exposure;
• after repeated courses;

then that belief could create false reassurance.

The regulatory wording therefore needed to communicate that absence of previous problems does not eliminate future risk.

Evidence Question 3: Can Symptoms Be Recognised Early?

This became a major part of the final risk-minimisation strategy.

The symptoms highlighted in the updated product information include:

• fever;
• chills;
• sore throat;
• painful mucosal changes, particularly in the mouth, nose and throat or genital and anal regions.

Patients are instructed to discontinue treatment and seek immediate medical attention if such symptoms develop.

The assessment also recognised an important clinical problem.

When metamizole is being taken to treat fever, fever itself may be interpreted as the underlying condition rather than as an early manifestation of agranulocytosis.

The EMA communication also notes that concomitant antibiotic therapy can mask symptoms.

This means that risk minimisation cannot simply assume that the adverse reaction will announce itself in an obvious way.

The detection strategy needs to account for clinical context.

Evidence Question 4: Does Routine Blood-Count Monitoring Prevent Serious Outcomes?

This is one of the most instructive aspects of the case.

Agranulocytosis is a haematological event.

A seemingly intuitive response would therefore be:

Monitor the blood count regularly.

The regulatory review did not support that approach.

The final EMA communication states that the review did not identify evidence supporting the effectiveness of routine blood-count monitoring for early detection of metamizole-induced agranulocytosis.

Routine monitoring was therefore removed from the product-information recommendations.

Instead, when symptoms suggestive of agranulocytosis occur:

1. treatment should be discontinued;
2. a blood count, including differential blood count, should be performed immediately;
3. treatment should remain discontinued while awaiting results;
4. if agranulocytosis is confirmed, treatment should not be reintroduced.

This is an important example of evidence-based risk minimisation.

Biological plausibility alone was not considered sufficient.

The intervention had to have a credible and supported ability to improve the clinical outcome.

Evidence Question 5: Are There Higher-Risk Populations?

The regulatory review identified patient groups in whom metamizole should not be used.

The agreed product-information amendments include contraindications for patients with:

• a previous episode of agranulocytosis induced by metamizole;
• previous agranulocytosis induced by other pyrazolones or pyrazolidines;
• impaired bone-marrow function;
• diseases of the haematopoietic system.

This represents a shift from a universal warning to targeted risk minimisation.

The principle is broader than metamizole.

When evidence supports identification of a population with materially greater susceptibility, the regulatory response can become more specific.

That can be more useful than simply strengthening a general warning applicable to everyone.

Evidence Question 6: Does the Risk Change With Dose or Duration?

The final product information explicitly states that metamizole-induced agranulocytosis is not dose-dependent.

It can occur at any time during treatment and shortly after treatment discontinuation.

The agreed amendments also removed wording suggesting that the risk was increased after one week or with long-term use.

This is an important example of correcting risk communication.

An earlier statement that implicitly concentrates risk within a particular treatment window can itself become a risk-minimisation problem if the available evidence no longer supports it.

Historical signal evaluation should therefore examine not only what was added to product information, but also what was removed.

The Regulatory Conclusion

The PRAC conclusion was not that metamizole should be withdrawn from the EU market.

The committee concluded that the benefits of metamizole-containing medicines continued to outweigh their risks.

However, existing product information required updating to improve awareness of agranulocytosis and facilitate early detection and diagnosis.

This is a critical distinction.

The outcome can be summarised as:

Known serious risk

→

continuing concern despite existing measures

→

reassessment of evidence and effectiveness of risk minimisation

→

strengthened and refined measures

rather than:

new adverse reaction discovered

→

medicine withdrawn.

This distinction should be preserved when describing the historical signal.

The Product-Information Delta

One of the most useful ways to study the regulatory outcome is to compare the nature of the changes to the SmPC.

The final Annex III wording required several important modifications.

The significance of this table is methodological.

A regulatory outcome is not adequately described by saying:

"The warning was strengthened."

The more informative question is:

What exactly changed, and what does each change tell us about the evidence assessment?

Before and After: Interpreting the Regulatory Delta

Before the 2024 Review

Agranulocytosis was already recognised as a serious adverse reaction.

Warnings and risk-minimisation measures existed, but approaches differed between countries.

Finland had recently strengthened its measures, yet cases continued to be reported.

During the Review

PRAC evaluated:

• the magnitude of the risk;
• time to onset;
• clinical consequences;
• risk factors;
• existing risk-minimisation;
• literature;
• post-marketing safety data;
• stakeholder information;
• potential additional measures.

After the Review

The European approach became more explicit regarding:

• symptoms;
• immediate clinical action;
• timing;
• dose relationship;
• susceptible populations;
• diagnostic testing;
• treatment discontinuation;
• avoidance of rechallenge.

Routine blood-count monitoring was not retained as a routine preventive measure.

This is more than an increase in warning language.

It is a change in the operational model of risk management.

Why Removal of a Monitoring Recommendation Matters

Pharmacovigilance discussions often focus on measures that are added.

The removal of a measure can be equally informative.

The metamizole case demonstrates why.

Suppose a risk is:

• potentially severe;
• relatively uncommon;
• idiosyncratic;
• not dose-dependent;
• capable of occurring at variable times;
• difficult to predict in advance.

Regular laboratory testing may appear attractive.

But if the event cannot reliably be predicted by scheduled testing, and if evidence does not demonstrate that routine monitoring improves outcomes, regular monitoring may impose burden without providing meaningful protection.

The regulatory conclusion therefore demonstrates an important principle:

Risk minimisation should be evaluated for effectiveness, not merely for plausibility.

This is highly relevant to QPPV oversight.

A risk-minimisation measure should have a defined rationale and, where appropriate, a means of assessing whether it is achieving its intended objective.

Signal Evaluation Versus Risk-Minimisation Evaluation

The metamizole case demonstrates why these two analytical questions should not be collapsed.

Signal evaluation asks

• Is there evidence of an association?
• How credible is the association?
• What alternative explanations exist?
• What is the clinical phenotype?
• What is the magnitude and seriousness of the risk?
• Are there risk factors?

Risk-minimisation evaluation asks

• What intervention could reduce the risk?
• Is the intervention feasible?
• Does it act at the relevant point in the clinical pathway?
• Is there evidence that it works?
• Could it create false reassurance?
• Could it introduce unintended burden?
• How will effectiveness be measured?

A safety issue may have a sufficiently established association while still requiring substantial additional work to determine the best risk-minimisation strategy.

That is precisely what makes the metamizole review valuable as a teaching case.

What the SmPC Reveals About the Regulatory Reasoning

The SmPC is not a transcript of PRAC deliberations.

However, changes in product information can provide a useful observable endpoint of the regulatory decision.

For example:

Addition of symptom-based warnings

This indicates the importance assigned to early recognition.

Immediate blood-count testing when symptoms occur

This indicates that clinical suspicion was considered a more appropriate trigger for diagnostic testing than routine screening.

Removal of routine blood-count monitoring

This indicates that routine screening was not supported as an effective early-detection strategy.

Removal of statements implying higher risk after one week or with long-term use

This indicates that the risk should not be communicated as confined to prolonged or delayed exposure.

Contraindications for specified populations

This indicates that targeted avoidance was considered appropriate for patients with particular susceptibility.

Prohibition of rechallenge after confirmed agranulocytosis

This reflects the seriousness of recurrence after a previous drug-associated episode.

The product-information changes therefore allow a reader to trace the broad direction of the regulatory reasoning even though the complete deliberative process is not public.

What This Case Teaches About Historical Signal Evaluation

1. A Signal Is Not a Conclusion

A safety signal is a hypothesis requiring evaluation.

The existence of reports does not, by itself, establish causality.

In this case, however, the adverse reaction was already recognised, so the 2024 question was principally one of risk characterisation and risk-minimisation adequacy.

2. The Same Safety Issue Can Generate Different Regulatory Questions Over Time

The initial recognition of a drug-event association is one stage.

Later questions may include:

• Is the magnitude of risk still accurately characterised?
• Are there newly recognised risk factors?
• Are existing warnings effective?
• Are healthcare professionals recognising the event early enough?
• Are patients being adequately informed?
• Is routine monitoring useful?
• Is the benefit-risk balance unchanged?

A mature PV system must be capable of revisiting an established risk rather than treating an old conclusion as permanently settled.

3. Continuing Cases Do Not Automatically Mean the Risk-Minimisation Strategy Has Failed

Cases can continue to occur even when a risk-minimisation measure is effective.

The correct question is whether the measure changes the frequency, severity, time to recognition or clinical outcome in the intended direction.

For this reason, the presence of cases after implementation is not by itself sufficient evidence that a measure has failed.

The effectiveness assessment needs an appropriate denominator, comparator or other analytical framework where feasible.

4. A New Warning Is Not Always the Best Intervention

The metamizole outcome did not simply add another generic caution.

It changed the clinical instructions around:

• symptom recognition;
• immediate action;
• diagnostic testing;
• treatment discontinuation;
• contraindicated populations.

This is more targeted than simply increasing the volume of warning text.

5. Removing Information Can Improve Risk Communication

Removing unsupported statements can be as important as adding new ones.

In this case, wording implying increased risk after one week or during long-term treatment was removed.

This helps avoid creating an inaccurate mental model of the risk.

6. Product Information Can Be Used as a Historical Endpoint

When the dates of product-information versions are known, the evolution of wording can provide a useful visible record of regulatory change.

The most useful comparison is not merely:

old wording versus new wording

but:

old risk characterisation → new evidence → regulatory assessment → new risk characterisation.

That is the central methodology of this historical evaluation series.

What a QPPV Should Ask When Reassessing a Known Risk

A QPPV reviewing a mature safety concern should consider questions such as:

Evidence

• What new evidence has accumulated?
• Does it change the strength of association?
• Does it change the estimated magnitude of risk?
• Does it identify new risk factors?
• Does it change understanding of timing or clinical presentation?

Clinical relevance

• What are the serious outcomes?
• How quickly can they develop?
• Are early symptoms recognisable?
• Are symptoms potentially masked by the indication or concomitant treatment?
• Is there a clinically meaningful intervention point?

Risk minimisation

• What measures are currently in place?
• Why were they introduced?
• What evidence supports their effectiveness?
• Are they actually being implemented?
• Are they creating false reassurance?
• Are they still proportionate?

Product information

• Does the SmPC accurately describe the current risk?
• Does it communicate the clinically important features?
• Is any wording outdated?
• Are there contradictions between sections?
• Are there statements that imply unsupported timing, dose or population effects?

Governance

• Is the issue being adequately monitored?
• Is effectiveness evaluation defined?
• Are signals, aggregate reports and emerging evidence aligned?
• Are changes in product information being tracked?
• Are regulatory commitments being closed effectively?

These questions move the analysis from simple signal detection toward genuine safety governance.

Limitations of the Public Reconstruction

A public historical evaluation necessarily has limitations.

The published record does not provide:

• every individual case report;
• complete EudraVigilance data;
• all MAH analyses;
• confidential epidemiological analyses;
• internal company benefit-risk assessments;
• every committee discussion;
• every sensitivity analysis considered during the procedure.

Therefore, this article should not be presented as a reproduction of the complete PRAC assessment process.

It is a reconstruction based on publicly accessible evidence.

There is also an important temporal limitation.

Evidence published after the regulatory decision cannot legitimately be described as evidence that PRAC considered during the 2024 evaluation unless the regulatory record demonstrates that it was available to the committee at the relevant time.

For historical signal evaluation, the evidence should therefore be divided into:

Evidence available during the regulatory assessment

and

Evidence published subsequently.

Later evidence may be useful for evaluating how scientific understanding has evolved, but it should not be retrospectively inserted into the original regulatory evidence base.

Subsequent Scientific Evidence

Subsequent publications continue to examine metamizole-associated agranulocytosis.

A later systematic review and pharmacovigilance analysis examined studies published after 2015 together with EudraVigilance data and reported an increased likelihood of reporting agranulocytosis with metamizole compared with several comparator groups.

This later analysis is useful context, but it should not be used to rewrite the evidence base of the 2024 regulatory decision.

Similarly, subsequent research into pharmacogenetic susceptibility may help refine future understanding of individual risk, but later evidence should remain temporally separated from the evidence that supported the 2024 regulatory conclusion.

This separation is essential if historical signal evaluations are to remain scientifically defensible.

Regulatory Outcome

The overall regulatory outcome can be summarised as follows:

Safety issue

Known serious risk of metamizole-associated agranulocytosis.

Trigger

Continuing cases despite strengthened national risk-minimisation measures.

Regulatory question

Whether the risk remained adequately characterised and whether existing risk-minimisation measures were sufficient.

Evidence considered

Scientific literature, post-marketing safety data, stakeholder information and information supplied during the procedure.

Conclusion

The benefit-risk balance remained positive, but existing product information and risk-minimisation measures required strengthening and refinement.

Major changes

• stronger warnings;
• clearer symptom recognition;
• immediate investigation when agranulocytosis is suspected;
• immediate treatment discontinuation while awaiting results;
• no rechallenge after confirmed agranulocytosis;
• contraindications for specified higher-risk populations;
• removal of routine blood-count monitoring;
• removal of wording implying increased risk specifically after one week or with long-term use.

This is a useful example of a regulatory outcome in which the medicine remains authorised but the management of a known safety risk is materially changed.

Overall Assessment

The metamizole–agranulocytosis case is a strong first example for a historical signal-evaluation series because it demonstrates that mature pharmacovigilance is not simply about discovering new adverse reactions.

The safety issue was already known.

The regulatory challenge was to determine whether the existing understanding and management of that risk remained adequate.

The 2024 evaluation therefore addressed several distinct dimensions:

• magnitude of risk;
• timing of onset;
• clinical presentation;
• susceptible populations;
• effectiveness of existing risk-minimisation;
• usefulness of routine monitoring;
• product-information accuracy;
• benefit-risk balance.

The resulting changes show how regulatory conclusions can translate into practical safety instructions.

The most important lesson is not:

Metamizole causes agranulocytosis.

That was already established.

The more useful lesson is:

When a known serious safety risk continues to occur despite risk-minimisation measures, the appropriate regulatory response may be to reassess how the risk is characterised and how the intervention works, rather than simply adding another warning.

The metamizole review demonstrates this clearly.

It also illustrates why historical signal evaluation should examine the complete pathway:

signal or regulatory concern

→

question definition

→

evidence available at the time

→

integrated assessment

→

risk-minimisation assessment

→

regulatory conclusion

→

product-information change

→

subsequent evidence.

That pathway provides a more useful model for pharmacovigilance professionals than treating signal management as an isolated statistical exercise.

Key Takeaways

A historical signal evaluation should distinguish between discovery of a new adverse reaction and reassessment of an established safety risk.

The 2024 EU metamizole procedure concerned a known serious risk of agranulocytosis.

The procedure was initiated after cases continued to occur despite strengthened risk-minimisation measures in Finland.

PRAC considered scientific literature, post-marketing safety information and stakeholder submissions.

The assessment considered not only the existence of the risk but its magnitude, timing, risk factors and the effectiveness of existing risk-minimisation measures.

Routine blood-count monitoring was not retained because the review did not identify evidence supporting its effectiveness for early detection.

The product information was strengthened to emphasise symptom recognition, immediate investigation and treatment discontinuation.

Specific higher-risk populations were identified through contraindications.

The product information was also amended to remove wording suggesting that the risk was specifically increased after one week or with long-term use.

The benefit-risk balance remained positive.

The case demonstrates that a mature safety evaluation can result in substantial changes to risk management without requiring withdrawal of the medicine.

Most importantly, the case demonstrates why historical signal evaluation should follow the evidence all the way through to its regulatory consequence.

The SmPC is not the regulatory reasoning itself, but its evolution provides an important observable endpoint for understanding how the final safety conclusion was translated into clinical risk communication and management.

References

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4. European Medicines Agency. Metamizole-containing medicinal products – Article 107i referral: Assessment report. EMA/470471/2024. 2024.

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6. European Medicines Agency. EMA recommends measures to minimise serious outcomes of known side effect with painkiller metamizole. September 2024.

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