Sedation Characteristics of Intranasal Alfaxalone in Adult Yucatan Swine

Abstract

Compared with intravenous and intramuscular methods, intranasal administration of sedatives is a less invasive and nonpainful technique. In this prospective, randomized, crossover study, we evaluated the sedative characteristics of 2 doses (1 and 2 mg/kg) of alfaxalone administered intranasally to 7 adult Yucatan swine. We compared sedation scores before and after administration of alfaxalone and between groups by using a composite sedation scoring system (range, 0 to 12, with 12 being the highest level of sedation)). Pigs were randomly assigned to receive 2 doses of intranasal alfaxalone (1 mg/kg [A1]); 2 mg/kg [A2]) as 2 separate events in a crossover design with a 60-d washout period. Categories scored were posture, palpebral droop, uninhibited behavior, drowsiness, and acceptance of anesthetic facemask. Sedation scores were collected before sedation was administered and then every 3 min for 30 min afterward. Instilled volumes (mean ± 1 SD) were 5.7 ± 0.5 and 11.3 ± 0.8 mL for A1 and A2, respectively. Both alfaxalone doses produced significant increases in sedation scores compared with baseline. Median sedation scores for A1 (6; range, 4–12) were not different from those for A2 (6; range, 6 to 12). Intranasal administration of alfaxalone as the sole sedative agent increased sedation scores from baseline, achieving peak sedation at 6 to 9 min after instillation of A2. However, sedation scores were similar between the 2 groups, and neither dose produced sufficient sedation to facilitate handling or the performance of any clinical procedures. Given the concentration of alfaxalone solution currently available, volume is the major limiting factor regarding testing higher doses of this drug for its use as a sole sedative agent in swine.