Stability of Ketamine-Xylazine-Butorphanol formulation supports evidence-based beyond-use date

Researchers at Auburn University have demonstrated that a commonly used sedation formula for New World Camelids—containing ketamine, xylazine, and butorphanol (KXB)—remains chemically stable for at least three months when stored at room temperature. The study, published in Current Pharmaceutical Analysis, also confirmed that the formulation stays free of bacterial and fungal contamination for up to 28 days, meeting and exceeding current USP <797> standards for Category 2 sterile preparations.

The team developed and validated a high-performance liquid chromatography method to simultaneously measure all three drugs. Under accelerated conditions at 40°C and room temperature (23°C), all active ingredients remained within 90–110% of their initial concentrations over three months. The formulation stayed clear and maintained a consistent pH of 4.1–4.3. No microbial growth was detected at 28 days or even at 45 days.

"This evidence-based beyond-use date allows veterinary pharmacies to prepare the KXB formulation in larger batches, reducing waste and improving workflow efficiency," said Susan M. Elrod, corresponding author from Auburn's College of Veterinary Medicine. "Importantly, it assures clinicians that the sedative remains potent and sterile throughout its labeled storage period, even under field conditions."

The KXB mix is widely used in llamas, alpacas, sheep, and goats for standing sedation or short-term anesthesia. Previously, pharmacies had to discard unused portions after 28 days due to lack of stability data. This study provides the scientific foundation to confidently extend that window, though the authors emphasize that aseptic compounding and proper handling remain essential.