Development of a romifidine constant rate infusion with or without butorphanol for standing sedation of horses.

This study aimed to determine protocols for a constant rate infusion (CRI) of the drugs romifidine, used alone or in combination with butorphanol, in order to achieve constant sedation in horses. The findings suggest that both protocols, whether with romifidine alone or in combination with butorphanol, provide constant sedation, though adding butorphanol resulted in greater ataxia, or lack of muscle control.

Methods applied in the research

• The research was conducted as a blinded randomized crossover study on ten adult research horses.
• Initially, the normal height of a horse’s head above the ground (HHAG) was determined and set as 100%.
• Then, loading doses of romifidine, with butorphanol (RB) or saline (R), were administered intravenously.
• Following this, a butorphanol or saline CRI was administered for two hours.
• The HHAG was used as a marker to determine the depth of sedation.
• Additional doses of romifidine were given whenever the HHAG was more than 50% to maintain sedation for two hours.
• The dose rate of romifidine required to maintain sedation was calculated for both treatments.

Results of the Research Study

• The research found no significant difference in the amount of romifidine required whether used singly (R) or with butorphanol (RB).
• The time to first additional dose of romifidine was significantly longer when it was combined with butorphanol.
• During the second hour of constant rate infusion, stable plasma concentrations of romifidian were achieved.
• However, when butorphanol was added to romifidine, it resulted in greater ataxia in the horses.

Conclusions of the Study

• The bolus of romifidine, followed by constant rate infusion, provided constant sedation, as assessed by the horses’ head height above the ground.
• In unstimulated conditions, adding butorphanol did not reduce the need for romifidine, but it did extend the duration of sedation triggered by the initial romifidine dose.
• However, these findings were based on non-clinical conditions, so both protocols need to be tested under clinical conditions for better analysis and refinement.