Sedative effects of an intramuscular or intranasal combination of sufentanil and midazolam in New Zealand White rabbits

To evaluate the sedative effects of a combination of sufentanil and midazolam administered intramuscularly (IM) or intranasally (IN) prior to induction of anesthesia with propofol in New Zealand White rabbits. Prospective, randomized, crossover, experimental study. A total of 11 adult New Zealand White rabbits. Sufentanil (0.5 μg kg–1) and midazolam (2 mg kg–1) were administered to rabbits via IM or IN route. The righting reflex was assessed, and sedation was scored. Heart rate, respiratory rate (fR) and temperature were recorded prior to treatment administration and after loss of the righting reflex. Measured variables remained within normal physiologic ranges for all rabbits. The only statistically significant change was for fR, which was significantly lower after sedation for both routes. The time to loss of righting reflex was 14.8 ± 6.5 and 12.5 ± 7.4 minutes and sedation scores were 6 (4–8) and 7 (6–8) for IM and IN routes, respectively, with no difference between treatments. No adverse effects were observed during the experimental period. Sufentanil combined with midazolam administered either IM or IN resulted in moderate to deep sedation in New Zealand White rabbits at the dose rates studied.