Fentanyl Transdermal Therapeutic System Provides Rapid Systemic Fentanyl Absorption in Two Ball Pythons (Python regius)

Abstract

Abstract Although our understanding of reptile analgesia continues to develop, μ-opioid receptor agonists are currently the most effective analgesics in a variety of reptile species. Fentanyl, a potent, short-acting, μ- and δ-opioid receptor agonist, is formulated for use as a transdermal therapeutic system (TTS) and was shown to be absorbed across the skin of prehensile-tailed skinks (Corucia zebrata). Snakes, which possess highly permeable skin, seem to be ideal candidates for effective transdermal analgesia. Fentanyl TTS (12 μg/h) was applied to the midbody, dorsal surface of two ball pythons (Python regius). Specimen mean body weight was 2.60 kg (2.20–2.99 kg). Cardiac blood samples were collected for 7 days, and plasma fentanyl concentrations were determined using high-performance liquid chromatography–mass spectroscopy. Therapeutic concentrations, as defined in mammals (1 ng/ml), were reached within 4 h of patch application, and they were sustained throughout the study. Plasma fentanyl steady-state ...