Preliminary investigation into a novel sustained-release formulation of meloxicam in sheep (Ovis aries)— pharmacokinetic profile

Abstract

This study is a preliminary investigation describing the pharmacokinetic profile of a novel subcutaneous sustained-release meloxicam formulation (SRMF) in sheep. Six merino ewe hoggets (41.5 ± 4.6 kg) were treated with a novel subcutaneous SRMF at 2 mg/kg bodyweight (BW). Blood samples were collected at t = 0, 2, 4, 6, 8, 10, 12, 24, 48, 96, 144, 168, 192, and 336 h following treatment, and interstitial (ISF) fluid samples were collected at periods of 8 to 12 h, 12 to 24 h, 24 to 48 h, 48 to 52 h, and 92 to 96 h following treatment. High-pressure liquid chromatography (HPLC) analysis with ultraviolet detection was utilised to determine the concentration of meloxicam in plasma and ISF. The SRMF exhibited the following mean (±SD) pharmacokinetic indices: Cmax of 1.58 μg/mL (±0.82 μg/mL) at a Tmax of 10.0 h (±1.79 h), and half life (t1/2) of 31.4 h (±13.17 h) in sheep plasma. Interstitial fluid samples were collected from three of the six sheep, with a decrease in meloxicam concentration exhibited over 52 h. This study demonstrates a variable extended t1/2, a delayed Tmax, and a lower Cmax of the SRMF, as compared to that of a conventional meloxicam formulation (CMF) in sheep, as previously referenced (t1/2: 14.28 h; Tmax: 5 h; Cmax: 15.94 μg/mL). Further research to determine the clinical efficacy and safety of the SRMF in sheep is warranted.