Role of Magnesium Sulfate in Asthma

"Magnesium sulfate has been shown to inhibit smooth muscle contraction, decrease histamine release from mast cells, and inhibit acetylcholine release. Studies both in children and adults have shown variable improvement in patients with severe airflow limitation who are unresponsive to standard treatment with beta agonist, anticholinergic, and corticosteroid medications. Ciarallo has shown in 2 studies of children that the optimum dose is 40 mg/kg given as an intravenous bolus with a maximum dose of 2 g.[1] In 1 study, improvement in forced expiratory volume in 1 second (FEV1) was seen within 20 minutes and continued for up to 110 minutes. Up to a 20% improvement in FEV1 may be seen. In adults, a study by Silverman has shown that patients with an initial FEV1 lower than 25% of what was predicted benefited the most from magnesium sulfate therapy.[2]"