Pharmacokinetics of Meloxicam (Metacam) After Intravenous, Intramuscular and Oral Administration to Red-Eared Slider Turtles (Trachemys scripta elegans)
1Toxicology and Pharmacology Department, Veterinary Faculty, Complutense University, Madrid, Spain; 2Veterinary and Laboratory Department, L'Oceanogràfic, Parques Reunidos Group, Ciutat de les Arts i de les Ciències, Valencia, Spain
Meloxicam is a non-steroidal anti-inflammatory drug (NSAID) widely used in veterinary medicine that has shown preferential inhibition of cyclo-oxygenase-2 and a potent analgesic and anti-inflammatory activity. In the present study, sodium meloxicam (Metacam®, injectable solution, 5 mg/ml, Boehringer Ingelheim España, S.A., Sant Cugat del Vallès, Barcelona, Spain) was administered to healthy adult red-eared slider turtles (Trachemys scripta elegans; n=12) by intravenous (0.22 mg/kg), intramuscular (0.5 mg/kg) and oral routes (0.5 mg/kg) in order to investigate the basic clinical pharmacokinetics of the drug. After administration, blood samples were collected serially from the dorsal cervical, subcarapacial sinus (vein), and meloxicam concentrations were determined by high performance liquid chromatography. After intravenous injection plasma meloxicam levels decreased rapidly; the elimination half-life was 7.57 hr and clearance resulted in 19 ml/hr/kg. The volume of distribution at steady state (180 ml/kg) was small, similar to values obtained in other animal species and for other nonsteroidal anti-inflammatory drugs. The drug was quickly absorbed after both intramuscular and oral routes (absorption half-lives: 17.18 and 25.93 min, respectively), but bioavailability and maximum concentrations were higher after intramuscular (85.38%; 3.19 μg/ml) than after oral dosing (36.81%; 0.31 μg/ml). Moreover, after oral dose the meloxicam plasma levels presented secondary peaks and a remarkable individual variability, resulting in larger elimination half-life and mean residence time values than after intramuscular administration. These results indicate that meloxicam presents better and more predictable clinical pharmacokinetic behaviour in red- eared slider turtle after intramuscular than after oral route.