Pharmacokinetics, sedation and hemodynamic changes following the administration of oral transmucosal detomidine gel in cats

Abstract

Objectives The aim of this study was to describe the pharmacokinetics of oral transmucosal (OTM) detomidine gel in healthy cats and assess its effects on sedation and hemodynamic variables. Methods Eight adult cats weighing 4.12 kg ± 0.72 received 4 mg/m2 detomidine gel onto the buccal mucosa. Level of sedation, heart rate (HR), blood pressure (BP) and respiratory rate ( f R) were assessed at predetermined intervals following administration. Blood samples for plasma detomidine concentrations and venous blood gas variables were collected from a medial saphenous catheter. Plasma detomidine concentrations were analyzed using ultra-high-pressure liquid chromatography with mass spectrometry detection, and pharmacokinetic estimates were obtained with compartmental methods. Data were analyzed using ANOVA and paired t-test or appropriate non-parametric tests. Results Sedation occurred in all cats, and was increased from baseline at 30 mins ( P <0.001). Decreases in HR occurred from 15–60 mins, ranging from 140 to 165 beats per min ( P <0.001). Blood glucose increased from 101 ± 12 mg/dl to 168 ± 27.3 mg/dl at 60 mins ( P = 0.004). Systolic blood pressure decreased from baseline (139 ± 14.8 mmHg) to 103 ± 23.0 mmHg at 60 mins ( P = 0.023). All changes abated by 120 mins. Emesis occurred in 7/7 cats within 2 mins of gel administration. Geometric mean (coefficient of variation) for clearance was 220.7 ml/min/kg (35.3 ml/min/kg), volume of distribution was 14.9 l/kg (39.9 l/kg) (both a function of bioavailability) and elimination half-life was 46.9 mins (16.0 mins). Maximum plasma concentrations of 10.5 ng/ml (35.5 ng/ml) detomidine occurred at 36.9 mins (21.5 mins). Conclusions and relevance OTM detomidine gel produced moderate sedation with minimal undesirable side effects in healthy cats, although emesis occurred in all cats. The pharmacokinetic profile supports short-term, minimally invasive sedation in this species. Further studies are warranted to assess its safety and feasibility for use in debilitated cats, or prior to general anesthesia.