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February 13, 1995

Lack of Effectiveness of Magnesium in Chronic Stable Asthma: A Prospective, Randomized, Double-blind, Placebo-Controlled, Crossover Trial in Normal Subjects and in Patients With Chronic Stable Asthma

Author Affiliations

From the Department of Medicine, Sinai Hospital of Baltimore (Md) (Drs Bernstein, T. Khastgir, A. Khastgir, Schonfeld, Nissim, and Chernow, Mr Hernandez, and Ms Miller); and Departments of Anesthesia and Critical Care Medicine (Drs Bernstein and Chernow) and Medicine (Drs Schonfeld, Nissim, and Chernow), The Johns Hopkins University School of Medicine, Baltimore. Dr T. Khastgir is now with the Department of Cardiology, University of Oklahoma Health Science Center, Oklahoma City; Dr A. Khastgir is now with the Department of Nephrology, Veterans Affairs Medical Center, Oklahoma City.

Arch Intern Med. 1995;155(3):271-276. doi:10.1001/archinte.1995.00430030061006

Background:  Magnesium sulfate has been helpful in the treatment of acute exacerbations of asthma. We hypothesized that magnesium would also be an effective bronchodilator in patients with chronic stable asthma.

Methods:  We performed a prospective, randomized, double-blind, placebo-controlled, crossover trial in 15 patients with chronic, stable asthma and 10 nonasthmatics. On study day 1, spirometry and albuterol challenge were used to confirm the presence of asthma according to American Thoracic Society criteria. On study day 2, subjects received intravenous magnesium sulfate (2 g) or placebo (saline). On study day 3, subjects were crossed over to receive the other drug. Spirometry was performed before, during, and after drug or placebo administration. Circulating ionized magnesium concentrations were determined before and after intravenous magnesium or placebo administration.

Results:  Magnesium infusion caused no statistically significant changes in forced expiratory volume in 1 second (mean±SEM, 1.92±0.13L before, 1.98±0.12L during, and 2.01±0.14 L after magnesium administration), forced vital capacity (mean±SEM, 3.44±0.25 L before, 3.60±0.26 L during, and 3.59±0.25 L after magnesium administration), or maximum forced expiratory flow rate (mean±SEM, 5.42±0.44 L/second before, 5.46±0.46 L/second during, and 5.57±0.49 L/second after magnesium administration). Placebo caused no changes in these three physiologic variables.

Conclusion:  Magnesium is not effective as a bronchodilator in chronic, stable asthmatics or in normal non-asthmatic adults.(Arch Intern Med. 1995;155:271-276)