The use of ketamine and amitriptyline compounded topically for the management of chronic neuropathic pain and itch is increasing. Topically administered ketamine can provide local analgesia, but systemic absorption, even at relatively low doses, may be associated with adverse psychotropic effects including alteration of both internal and external perceptions of reality.1 We present a case of systemic absorption and subsequent toxic encephalopathy following application of topical amitriptyline, ketamine, and lidocaine for recalcitrant pruritus.
Cardis MA, Pasieka HB. Safety of Topical Neuromodulators for the Treatment of Pruritus. JAMA Dermatol. Published online September 14, 2016. doi:10.1001/jamadermatol.2016.3118