Development of a new formulation for preparing oral provocation tests (OPT) for nuts in allergology

Introduction
The increasing prevalence of food allergies, particularly those related to peanuts and nuts makes them a public health issue. The oral provocation test (OPT) is the gold standard diagnostic tool, despite constraints related to safety, preparation and storage of fruit-based formulations. An innovative alternative is based on the use of de-oiled flours, which are easier to handle and potentially more reproducible, while maintaining diagnostic reliability.

Objective
To propose a new, suitable, reliable and reproducible formulation for OPTs with nuts, meeting the requirements of clinical protocols while ensuring patient safety.

Methods
A census of compounded preparations made between 2019 and 2024 was carried out using official records. A bibliographic search was conducted to compare the protein composition of nuts and the corresponding flours. The manufacturing processes for these flours were analysed to assess their suitability for use in allergology.

Results
The survey revealed a wide variability in the dosages used for OPTs, ranging from 1 to 10mg depending on the nuts. The protein content of de-oiled flours is approximately twice than whole nuts (average ratio ≈ 0.5), except of cashews (ratio ≈ 1). The manufacturing processes involve cooking, pressing and grinding steps, which can alter the protein structure. Cashews are the only non-de-oiled flour identified. De-oiled flours offer better reproducibility, but their production remains artisanal, limiting their accessibility.

Discussion and conclusion
The wide variability in prescribed doses, linked to patient profiles and clinical indications, complicates the standardisation of preparations. The protein difference between whole nut and flour requires consensus between prescribers and pharmacists. Cooking during the manufacturing process can cause protein denaturation, which is a potential source of false negatives. Despite their advantages, de-oiled flours suffer from technical limitations and availability issues. It appears necessary to develop standardised industrial specialities for OPTs, similar to Palforzia^® for peanuts. OPTs remain the diagnostic tool of choice, but their implementation remains partially empirical. Harmonisation of practices and better standardisation of formulations are essential to improve the safety and reliability of diagnosis.

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