Review of spontaneous reports with positive rechallenge: Data of Toulouse Pharmacovigilance Center - 08/05/26

Doi : 10.1016/j.therap.2026.04.004

Elsa Trime ^a, Joanna Lapalus ^a, Eda Cankurtaran ^a, Leila Chebane ^a, Mathis Hugot ^a, Adèle Le Guilloux ^b, Haleh Bagheri ^a,⁎

^a Department of Medical and Clinical Pharmacology, Regional Pharmacovigilance Centre of Toulouse, Clinical Investigation Centre 1436, Toulouse University Hospital, 31000 Toulouse, France

^b Department of Medical and Clinical Pharmacology, Methodological & Statistical supporting center MeDataS, Clinical Investigation Centre 1436, Toulouse University Hospital, 31000 Toulouse, France

^⁎ Corresponding author. Department of Medical and Clinical Pharmacology, Regional Pharmacovigilance Centre of Toulouse, 37, allées Jules Guesdes, 31000 Toulouse, France. Department of Medical and Clinical Pharmacology, Regional Pharmacovigilance Centre of Toulouse, 37, allées Jules Guesdes Toulouse 31000 France

Sous presse. Épreuves corrigées par l'auteur. Disponible en ligne depuis le Friday 08 May 2026

Abstract

Introduction

Apart from observational studies, anecdotal reports can offer evidence that an event is causally linked to one or more drugs and then could contribute to a better assessment of a drug's benefit-risk ratio. These reports based on temporality and dechallenge/rechallenge data have a real value and help to make safety decision.

Objective

The aim of our study was to describe the characteristics of positive rechallenge cases of adverse drug reactions (ADRs) reported to the Toulouse Pharmacovigilance Center (TPC), without restricting our analysis to any specific type of ADR or drug class. We described the drug class most commonly involved in the occurrence of serious ADRs following drug rechallenge.

Method

Retrospective study using data from the Toulouse Pharmacovigilance Database from 1st January 2022 until 31st December 2024. All cases of vaccines-induced ADRs were excluded. A descriptive analysis was done for demographic data, nature of ADRs and outcome, suspected drugs. Furthermore, the cases reported by the Department of Allergology for patients who underwent allergological investigation following a suspected hypersensitivity reaction were analyzed separately.

Results

Among the 8,196 ADR reports, 2,256 cases vaccine-related cases were excluded. Of the remaining 5,940 cases, 325 (5.5%) met the criteria for a positive rechallenge. The median age of patients was 57 years [35–72], mean 53.6 (±22.9) years and the sex ratio was 1.44. The outcome was fatal in three cases. The most drug class (more than 20 fold) involved in positive rechallenge cases was antineoplasic agents ( n = 105) and immunosuppressants ( n = 51), drugs of nervous system ( n = 95), systemic anti-infective agents ( n = 83), and cardiovascular drugs ( n = 54). A total of 187 cases concerned positive rechallenge for hypersensitivity reactions after allergological investigations.

Conclusion

Case reports containing dechallenge/rechallenge data could be considerable value for improving knowledge to support optimal drug use, particularly in situations where no alternative is available. This preliminary study limited to the data of one pharmacovigilance center could be extended in national level.

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Keywords : Pharmacovigilance, Positive rechallenge, Signal generation, Spontaneous reports