Plasma pharmacokinetic profile and efficacy of meloxicam administered subcutaneously and intramuscularly to sheep

• Published in: PloS one Vol. 14; no. 4; p. e0215842
• Main Authors: Woodland, Alyssa N, Van der Saag, Dominique, Kimble, Benjamin, White, Peter J, Govendir, Merran, Lomax, Sabrina
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 24.04.2019; Public Library of Science (PLoS)
• Subjects: Analgesics; Analysis; Animals; Anti-inflammatory agents; Beef cattle; Behavior, Animal - drug effects; Bioavailability; Blood plasma; Domestication; Dosage and administration; Drug dosages; Effectiveness; Environmental science; Extremities - physiology; Gait - physiology; Health aspects; Horses; Inflammation; Injections, Intramuscular; Injections, Subcutaneous; Laboratory animals; Meloxicam; Meloxicam - administration & dosage; Meloxicam - blood; Meloxicam - pharmacokinetics; Nonsteroidal anti-inflammatory drugs; Pain; Pharmacokinetics; Pharmacology; Physiology; Sensitivity; Sheep; Skin; Skin temperature; Skin Temperature - drug effects; Temperature; Treatment Outcome; Turpentine; Sydney New South Wales Australia; Australia
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0215842

Plasma pharmacokinetic profiles and the anti-inflammatory efficacy of meloxicam were determined when administered subcutaneously (SC) or intramuscularly (IM) to sheep. Merino ewes were initially injected with 0.1 mL of oil of turpentine into a forelimb to induce inflammation, followed by either 1.0 mg/kg or 2.0 mg/kg of meloxicam administered either SC or IM (n = 6 per treatment group) or followed by no meloxicam administration (control) (n = 4). Ewes were examined to determine skin temperature, limb circumference, limb sensitivity and signs of lameness at 0, 0.5, 1, 2, 4, 6, 8, 10, 12, 24 and 48 h following treatment, with blood collected at these time-points to quantify meloxicam plasma concentrations. Skin temperature of ewes dosed with meloxicam at 1.0 mg/kg SC and 2.0 mg/kg IM at 12 h and 1.0 mg/kg SC at 24 were significantly different to the controls (P < 0.05). Limb circumferences of ewes dosed with 1.0 mg/kg IM were significantly different to controls at 10 h and 12 h (P < 0.05). All meloxicam treatment groups resulted in reduced limb sensitivity compared to controls at 6 h, with the 1.0 and 2.0 mg/kg IM treatments significantly different at 12 h (P < 0.05) and 1.0 and 2.0 mg/kg SC groups, significantly different to controls at 48 h (P < 0.05). No significant difference in lameness scores were detected over 48 h. The 1.0 mg/kg IM treatment had a significantly greater plasma meloxicam concentration than the 1.0 mg/kg SC treatment over 0.5 to 4 h (P < 0.001). Both 1.0 mg/kg SC and IM treatments demonstrated elimination half-lives (mean ± SD) of 10.82 ± 2.46 and 12.63 ± 2.37 h, respectively. Meloxicam at all doses provided some anti-inflammatory and analgesic effects from 6 to 48 h; however no route could be distinguished as more efficacious than the others.