Wikipedia
Romifidine
Romifidine is a drug that is used in veterinary medicine as a sedative mainly in large animals such as horses, although it may be used in a wide variety of species. It is not used in humans, but is closely related in structure to the commonly used drug clonidine.
Romifidine acts as an agonist at the α adrenergic receptor subtype. Side effects can include bradycardia and respiratory depression. It is often used alongside other sedative or analgesic drugs such as ketamine or butorphanol. Yohimbine can be used as an antidote to rapidly reverse the effects.