Yohimbine hydrochloride is a specific α2A-adrenoreceptor antagonist with central action. It is an effective antagonist to xylazine in horses and camels. In horse, yohimbine hydrochloride is an effective antagonist to xylazine sedation in red, fallow. 4Aminopyridine is an antagonist to nondepolarising neuromuscular blocking drugs and is known to greatly enhance transmission at the neuromuscular junction and partially effects the number of anaesthetics and sedatives. The effects of the antagonist are mainly attributed to direct anatagonism of xylazine by 4-aminipyridine and yohimbine, there effects are only considered partial.