ABSTRACT
Reptile medicine is challenged by the need for effective analgesia options. Transdermal fentanyl (TDF) has been used extra-label in veterinary medicine for mammals as peri-operative analgesia. Through this application and human studies, it has been determined in these species that the rate-limiting process for TDF absorption is not transfer through patient skin. Therefore, although reptiles have scaled skin, fentanyl should be absorbed systemically when applied transdermally. Plasma concentrations of fentanyl were assayed by liquid chromatography-mass spectroscopy in six adult prehensile-tailed skinks, Corucia zebrata, during 72 h of TDF patch application and through 32 h after patch removal. Elimination half-life was determined for TDF in prehensile-tailed skinks as 16.2±10.7 h. In this species, fentanyl was systemically available from this route at concentrations considered effective for analgesia in humans. In skinks, and similarly scaled reptile species, this pharmaceutic formulation therefore should provide an additional analgesic option for the clinical patient.
