Isoxsuprine is a beta-adrenergic receptor agonist and a direct-acting peripheral vasodilator. It is primarily used in the management of peripheral vascular diseases, cerebrovascular insufficiency, and as a uterine relaxant in premature labor. It acts by relaxing vascular smooth muscle, leading to increased blood flow to ischemic areas.
Adult: Oral: 10-20 mg three or four times daily. Common starting dose is 10mg TID. Maximum daily dose: 80mg.
Note: Administer orally with or without food. Tablet should be swallowed whole with a glass of water. For tocolytic use, dosing is typically more frequent (e.g., every 3-4 hours) under hospital supervision.
Isoxsuprine acts as a beta-2 adrenergic receptor agonist, leading to relaxation of vascular smooth muscle in arteries, arterioles, and the uterus. It also has mild alpha-adrenergic receptor blocking activity, which contributes to vasodilation. The net effect is decreased peripheral vascular resistance and increased blood flow to skeletal muscles and skin without significantly affecting blood pressure at therapeutic doses.
Pregnancy: Category C (US FDA). Animal studies show risk, human data limited. Used as a tocolytic for premature labor, but benefits must outweigh risks. Should only be used under strict medical supervision in a hospital setting for this indication.
Driving: May cause dizziness, lightheadedness, or syncope, especially at initiation. Patients should not drive or operate machinery until they know how the drug affects them.
| Other Vasodilators (e.g., Nitrates, Hydralazine) | Additive hypotensive effect; risk of severe hypotension. | Major |
| Beta-blockers (e.g., Propranolol, Atenolol) | Antagonizes the vasodilatory effects of Isoxsuprine; may worsen peripheral vascular disease. | Major |
| Sympathomimetics (e.g., Epinephrine, Pseudoephedrine) | Increased risk of tachycardia and hypertension. | Moderate |
| Antihypertensives | Enhanced blood pressure lowering. | Moderate |
| MAO Inhibitors (e.g., Phenelzine) | Risk of hypertensive crisis. | Major |