Isoxsuprine

General information

Isoxsuprine is a beta ₂ -adrenoceptor agonist that also has antagonist action at alpha-adrenoceptors. It has been variously described as a beta-agonist, a specific vasorelaxant, a uterine relaxant, and an agent that reduces blood viscosity. In high dosages it also inhibits platelet aggregation. There is slim evidence that isoxsuprine improves cognitive function and mental performance in a limited number of patients, but the practical benefit is minor. There is no convincing proof of its efficacy in patients with claudication. It has been widely used in horses for treating navicular syndrome and laminitis, with little evidence of efficacy [ ].

Since its efficacy has been doubted with respect to both its vascular and its obstetric use, one must suspect that underdosage of the drug is the best explanation for the low reported incidence of adverse reactions, which are generally of the type regarded as anecdotal (nausea, vomiting, palpitation, dizziness, weakness). Minor facial flushing and tremor are common. As patients tend to increase the dosage gradually, diarrhea, vomiting, headache, vertigo, and rash can occur [ ]. The important adverse reactions of isoxsuprine are tachycardia and orthostatic hypotension, but they occur only at high dosages.