Antipruritic Effect of Topical Ketamine, Amitriptyline, and Lidocaine

The purpose of this study is to examine the antipruritic efficacy of topical ketamine, amitriptyline, lidocaine, and a tri-combination of ketamine, amitriptyline and lidocaine (hereafter referred to as "KeAmLi") using non-histaminergic itch provocations in healthy volunteers. The primary outcome is itch reduction (AUC) between the vehicle and active treatment (KeAmLi-combo). Secondary outcomes include modality-specific analgesic properties of the topically applied ketamine, amitriptyline, lidocaine, and KeAmLi-combo to controlled quantitative thermal and mechanical stimuli, which can improve our understanding of the mechanism of action of these substances in the context of topical therapy.