Concentrations of vatinoxan and xylazine in plasma, cerebrospinal fluid and brain tissue following intravenous administration in sheep

The Impact of Vatinoxan on the Concentrations of Medetomidine, Midazolam, and Fentanyl in Central Nervous System After Subcutaneous Co-Administration in Rats

Our aim was to investigate whether vatinoxan, a peripherally acting alpha2-adrenoceptor antagonist, would affect the concentrations of medetomidine, midazolam, and fentanyl in the central nervous system after subcutaneous co-administration. Twelve healthy male Wistar rats, aged between 13 and 15 weeks, were used in this study. The animals received one of two subcutaneously administered treatments: medetomidine 0.25 mg/kg, midazolam 2 mg/kg, and fentanyl 0.01 mg/kg (MMF) or MMF with 5 mg/kg of vatinoxan (MMF-V). 15 min later, the sedated rats were humanely euthanized with intravenous pentobarbital. Plasma and tissue, including aliquots of the cortex, thalamus, pons, and lumbar spinal cord, were harvested and analyzed for drug concentrations. The treatments were compared with Bonferroni corrected t-tests after one-way analysis of variance. The concentrations of medetomidine (144 ± 19.4 vs. 107 ± 13.1 ng/g [mean ± 95% confidence interval]) (p = 0.04) and fentanyl (2.3 ± 0.2 vs. 1.7 ± 0.3 ng/g) (p = 0.04) in the cortex were significantly higher in the rats administered MMF-V. Similarly, cortex: plasma drug concentration ratios were significantly higher for medetomidine, midazolam, and fentanyl after MMF-V (p < 0.001 for all). The results confirm that vatinoxan increases early cortical exposure to subcutaneously co-administered medetomidine and fentanyl.

Xylazine Poisoning in Clinical and Forensic Practice: Analysis Method, Characteristics, Mechanism and Future Challenges

Xylazine abuse is emerging globally, while the identification of xylazine lethal cases poses a great challenge in clinical and forensic practice. The non-specific symptoms delay the diagnosis and treatment of xylazine poisoning, the pathological changes and lethal concentration of xylazine in body fluid and organs of fatal xylazine poisoning cases are seldom reported and the other toxins detected in such cases complicate the role of xylazine in the cause of death. Therefore, we carefully reviewed related updated information on xylazine, summarized the knowledge from clinical and forensic perspectives and can thus provide a reference in such cases and throw light on further study in the field of xylazine poisoning.