Effects of IncobotulinumtoxinA in the Infraorbital Nerve Chronic Constriction Injury Model of Trigeminal Pain in Rats

Background/Objectives: Trigeminal neuralgia (TN) is a debilitating neurological condition characterized by recurrent, severe pain linked to peripheral and central sensitization within trigeminal pathways. Current pharmacologic treatments are limited by inadequate efficacy or dose-limiting side effects, and botulinum neurotoxin type A (BoNT/A) has emerged as a viable option. However, its potential use in the management of TN is hampered by methodological limitations in existing studies and a lack of pivotal clinical trials. This study investigated the efficacy, optimal treatment site, preventive utility, and duration of effect of incobotulinumtoxinA (Inco/A), a BoNT/A, in a model of TN. Methods: An infraorbital nerve chronic constriction injury model was used to induce mechanical allodynia in male Sprague-Dawley rats, reproducing the trigeminal sensitization seen in TN. The effects of subcutaneous Inco/A (1, 2, and 4 U) were measured using the mechanical sensitivity (von Frey) test to evaluate the dose response, effect of injection location, potential preventive nature of treatment, and duration of benefit. Results: Inco/A produced a robust, dose-dependent reduction in mechanical allodynia, predominantly via a local mechanism of action. Both preventive and therapeutic administration of Inco/A was efficacious, with significant reduction in allodynia even when administered up to 28 days before nerve injury. The anti-allodynic effect persisted up to 56 days post-injection. Conclusions: Inco/A is highly effective in alleviating mechanical allodynia in a validated rat model of TN. The findings highlight Inco/A as a promising candidate for clinical translation in TN and related neuropathic pain syndromes and support systematic investigation in well-controlled human trials.