Effect of parenteral magnesium sulfate on pulmonary functions in bronchial asthma

Eighteen patients with bronchial asthma were studied in a single-blind fashion. Each patient received an infusion of magnesium sulfate (MgSO4.7H2O 50% W/V) in a dose equivalent to 10 mmol of elemental magnesium. The airways resistance showed a significant decrease (p < 0.01) while SGaw increased significantly (p < 0.001) with MgSO4 infusion. FEV1 (p < 0.01), FEF25-75% (p < 0.05), and V50 (p < 0.05) also showed statistically significant increase (p < 0.001) with MgSO4 infusion. Significant changes in Raw (p < 0.01) and SGaw (p < 0.01) persisted at 10 and 20 min following MgSO4 infusion. No significant side effects were observed with MgSO4 infusion. It is concluded that modest improvement in airways resistance and specific conductance and only small improvement in maximal expiratory flow rates is consistent with a predominant effect of MgSO4 on large airways in patients with bronchial asthma.