Evaluation of the Feasibility of Preparing Patches in Vaseline for the Toxidermia Eploration in Immuno-Allergology

Background and Objectives
Toxidermia diagnosis in Immuno-Allergology (IA) is based on the reading of drug-based patch tests. Pharmacy produced them by crushing and diluting a tablet of the “commercial specialty” in NaCl. French recommendations have evolved towards patches in Vaseline, with a ratio of 30% of drug mass and 70% of Vaseline mass. The aim of this project is to assess the pharmaceutical human resources required to prepare these new patches.

Materials and Methods
From December 1^st, 2023 to February 29^th, 2024, and based on current production, we assessed the number of patches tested, and determined the panel of molecules tested.
The laboratories (Destaing^® and allergEAZE^®) were contacted to find out what was commercially available, to exclude molecules with a marketed alternative (ready-to-use syringe), and to identify molecules that would have to be manufactured by pharmacy.
The scope of the analysis concerns only molecules in dry form, as liquid forms are produced directly by the RN Department.
For eligible molecules, we carried out a double simulation (NaCl and Vaseline) and timed the handling time, without considering the management time, which we consider to be equivalent.

Results
Over the 3-month period, 89 different molecules were tested, for a total of 334 patches produced, with an average of 28 patches per week. Analysis of the laboratories’ offers shows that 19 references (21%) are marketed in ready-to-use form, i.e. 174 preparations (52%). Among our production, 21 molecules are not marketed, i.e. 66 preparations (an average of 6 preparations per week).
We produced 45 preparations in NaCl, with an average time of 1min26sec (0min36sec) per preparation, and 29 preparations in Vaseline, with an average time of 7min34sec (2min1sec) per preparation, i.e. an increase in production time of 6min and 8 seconds. Based on the estimated number of test patches per week, the additional production time is around 37 minutes.

Discussions – Conclusion
Most of the preparations are marketed by laboratories.
For the other preparations, we can envisage integrating this additional manufacturing time into the current activity of compounders. However, this point requires further investigation, with an analysis of retrospective data from 2022 and 2023.
However, only few studies on the stability of preparations in Vaseline are currently available, and the production of patches up to 24 hours before application is not compatible with the current organization. The financial aspect of this change in practice also needs to be explored.

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