Background and importance In France, 6.9% of the general population suffer from neuropathic pain.1 Among the causes are surgery (20%), including cancer surgery, and chemically induced paresthesia (4.1%).2 There are few treatments developed for this indication, and patients quickly find themselves in a therapeutic impasse. In addition, oral treatments could possibly cause undesired systemic effects.
Aim and objectives The aim was to develop and evaluate a topical form of amitryptiline at 10% for second-line treatment of patients.
Material and methods A galenic development was carried out following the recommendations of the International Council for Harmonisation (ICH) Q2 and 3 that addressed the galenic, physicochemical and microbiological parameters. Different types of topicals have been designed, from the cream to the thermogel with poloxamer.
Once the form was judged satisfactory on the pharmaceutical criteria, the preparation was assessed in the clinical context. Pain evaluation was carried out according to a visual analogue scale (VAS). A reduction of at least 30% was considered clinically relevant according to the recommendations of the French Society of Evaluation of the Treatment of the Pain.
Results The best compromise found was a 10% amitriptyline cream made in Versatile with urea at 2% as an emollient agent. This cream retains its diffusion properties, its organoleptic characteristics but also its physicochemical and microbiological stability for more than 6 months (stability data are still ongoing) in a PVC/ALU packaging.
81 patients were included (February–November 2020). For 49 patients (60.5%), the cream was effective. The etiologies for which the cream seems to be the most effective are post-chemotherapy pain (64% efficiency with taxane-based chemotherapy, 70% efficiency with platinum-based chemotherapy).
Conclusion and relevance The development of this topical has allowed neuropathic patients to gain relief. These data are very encouraging and will be confirmed through the implementation of a clinical trial.
References and/or acknowledgements 1. Bouhassira D, Lantéri-Minet M, Attal N, Laurent B, Touboul C. Prevalence of chronic pain with neuropathic characteristics in the general population. Pain 2008;136(3):380–7.
2. Torrance N, Smith BH, Bennett MI, Lee AJ. The epidemiology of chronic pain of predominantly neuropathic origin. Results from a general population survey. J Pain Off J Am Pain Soc 2006;7(4):281–9.
Conflict of interest No conflict of interest