Preliminary Investigation into a Novel Sustained-Release Formulation of Meloxicam in Sheep (Ovis aries)—Pharmacokinetic Profile

SIMPLE SUMMARY: Meloxicam is an effective non-steroidal anti-inflammatory drug (NSAID) suitable for ameliorating pain in sheep. Pain caused by husbandry procedures and other inflammatory conditions in sheep can persist for an extended time beyond the duration of action of currently available formulations of NSAIDs. This study investigates a novel sustained-release formulation of meloxicam to determine its potential for extended pain alleviation. Compared to a conventional formulation of meloxicam, the sustained-release formulation provided extended half-life making it a suitable candidate for providing extended pain relief. 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: C(max) of 1.58 μg/mL (±0.82 μg/mL) at a T(max) of 10.0 h (±1.79 h), and half life (t(1/2)) 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 t(1/2), a delayed T(max), and a lower C(max) of the SRMF, as compared to that of a conventional meloxicam formulation (CMF) in sheep, as previously referenced (t(1/2): 14.28 h; T(max): 5 h; C(max): 15.94 μg/mL). Further research to determine the clinical efficacy and safety of the SRMF in sheep is warranted.