Pharmacology: Pharmacodynamics: Isoxsuprine hydrochloride is a β2-adrenoceptor agonist that causes vasodilation by direct relaxation of vascular smooth muscle. Its β2-adrenergic effects, however, are not essential to its vasodilating effect. Isoxsuprine decreases peripheral vascular resistance; blood pressure may be decreased by parenteral administration or large oral doses of isoxsuprine. lsoxsuprine may also have positive inotropic and chronotropic effects on the heart and may increase cardiac output.
Isoxsuprine also relaxes uterine smooth muscle and is valuable in arresting contractions in threatened abortion and premature labor.
Pharmacokinetics: Isoxsuprine is almost completely absorbed from the gastrointestinal tract after oral administration and peak plasma concentrations occur within 1 hour and persist for about 3 hours. lsoxsuprine's mean plasma half-life is about 1.25 hours. It crosses the placenta.
Isoxsuprine is conjugated partially in the body and is excreted in urine. Isoxsuprine's fecal excretion is negligible.
No data is available on the onset of effect and peak plasma concentration of isoxsuprine hydrochloride when administered parenterally. With intramuscular (IM) injection, isoxsuprine's effect lasts for 3 to 4 hours.