Effect of MgSO₄ on FEV₁ in stable severe asthma patients with chronic airflow limitation

Abstract

Rationale: The bronchodilating potency of magnesium sulphate (MgSO₄) has been shown in acute asthma exacerbations. We hypothesized that smooth muscle cell relaxation by magnesium might also be beneficial in chronic severe asthma with persistent airflow limitation.

Aim: To investigate whether nebulised magnesium, administered according to a dosing scheme shown to be effective in acute asthma, induces bronchodilation in stable asthma patients with persistent airflow limitation.

Methods: In a placebo-controlled, cross-over study, 13 severe asthma patients with postbronchodilator FEV₁ < 75% predicted received either 2.5 mL MgSO₄ 6.4% or placebo in 3 nebulisations at 30 minute intervals. Before the first and 30 minutes after the last inhalation FEV₁, exhaled nitric oxide (NO) in dyspnoea (Borg) were measured.

Results: After MgSO₄ treatment no improvement in FEV₁ occurred (56.2 ± 16.8 to 55.4 ± 17.4% predicted [p = 0.5]), neither was a change in exhaled NO or Borg observed (p > 0.1). The changes in FEV₁, NO or Borg were not different between the treatment arms (p ≥ 0.09).

Conclusion: Short-term treatment with magnesium inhalations had no direct bronchodilating effect in stable severe asthma patients with persistent airflow limitation. Yet, clinical observations suggest a heterogeneity in response, probably related to treatment intensity, and support further exploration of magnesium administration in these patients.