Pharmacokinetics of Subcutaneous Hydromorphone Administration in Bearded Dragons (Pogona vitticeps)
Opioids are commonly used for pain management in reptiles, though few pharmacokinetic studies exist to determine effective dosages. Hydromorphone antinociceptive efficacy was previously demonstrated in red-eared slider turtles using a thermal noxious stimulus device.1 The objective of this study was to determine the pharmacokinetics of two subcutaneously administered dosages of hydromorphone (0.5 and 1.0 mg/kg) in six bearded dragons (Pogona vitticeps). The maximum concentration (Cmax) for subcutaneous administration at 0.5 and 1.0 mg/kg was 211 and 556 ng/ml, respectively, and both peaks were detected 30 minutes post hydromorphone administration. Hydromorphone administered subcutaneously at both dosages provided measurable plasma concentrations of hydromorphone for up to 12 hours with the longest measurable concentration detected at 24 hours. Clinical signs of sedation were observed for up to 1 hour post hydromorphone administration for most bearded dragons (five/six) when hydromorphone was administered at 1.0 mg/kg. Plasma concentrations of hydromorphone were detectable for up to 24 hours post administration in five/six bearded dragons receiving 1.0 mg/kg.
1. Mans C, Lahner LL, Baker BB, Johnson SM, Sladky KK. Antinociceptive efficacy of buprenorphine and hydromorphone in red-eared slider turtles (Trachemys scripta elegans). J Zoo Wildl Med. 2012;43(3):662–665.