Isoxsuprine is a modulator of β2 adrenoreceptor and has agonist or antagonist effects.

The β2 adrenoceptors are a class of G protein-coupled receptors that are targets for epinephrine. Many cells possess these receptors, the binding of epinephrine to the receptor will generally stimulates the sympathetic nervous system, resulting in muscle relaxation, vasodilation, diverting blood flow from non-essential organs to skeletal muscle and mobilizing energy [1].

As a modulator of β2 adrenoreceptor, Isoxsuprine is used as a vasodilator as well as smooth muscle modifier in humans. In vitro neuroprotection experiment, when administered up to an hour after reoxygenation, Isoxsuprine demonstrated no loss of neuron efficacy [2]..

In vivo animal stroke model, 1 mg/kg isoxsuprine was administered after a 90-minute occlusion of the right middle cerebral artery by IV injection at reperfusion. Total infarct volume in isoxsuprine-treated group was 137±18 mm3 compared to 279±25 mm3 in control group [2].

References:
1.  R. S. Ekert and C. G. Macallister. Isoxsuprine hydrochloride in the horse: A review. J. Vet. Pharmacol. Ther. 2002, 25(2), 81-87
2.  Hill JW, Thompson JF, Carter MB. Identification of isoxsuprine hydrochloride as a neuroprotectant in ischemic stroke through cell-based high-throughput screening. PLoS One. 2014 May 7; 9(5):e96761