Comparative pharmacokinetics of intravenous and intramuscular meloxicam in Awassi sheep: Implications for extended therapeutic efficacy

Meloxicam, a COX-2 preferential NSAID, is broadly used in veterinary medicine for analgesic and anti-inflammatory activity, but pharmacokinetic data in sheep remain restricted. This study compared plasma pharmacokinetic profiles of meloxicam administered intravenously (IV) and intramuscularly (IM) in Awassi sheep. A two-phase crossover design study with a 12-day washout was conducted in five healthy male Awassi sheep (26–34 kg). Meloxicam (0.5 mg/kg) was administered by IV or IM. Blood samples were collected at determined intervals (IV: 0.083–24 h; IM: 0.5–24 h). Plasma concentrations were quantified via spectrophotometry, and Pharmacokinetic (PK) parameters resulted from non-compartmental analysis. IV administration showed rapid distribution (C_max: 7.17 ± 0.17 μg/mL at 0.083 h) and prolonged t_1/2β (13.02 h). IM administration showed delayed absorption (T_max: 4 h; C_max: 7.08 ±0.04 μg/mL) and comparable t_1/2β (14.77 h). Both routes maintained plasma concentrations >1 μg/mL for >24 h. Key parameters include volume of distribution (V_d) (IV: 0.094 L/kg; IM: 0.078 L/kg), clearance (Cl) (IV: 0.0050 L/h/kg; IM: 0.0036 L/h/kg), and area under the plasma concentration-time curve extrapolated to infinity (AUC_0–∞) (IV: 98.95 μg×h/mL; IM: 135.36 μg×h/mL). Meloxicam revealed satisfactory PK properties with sustained therapeutic concentrations beyond 24 hours, supporting once-daily dosing for long-term pain management in sheep.