| 25.
Inhaled magnesium sulphate enhances bronchodilatation in severe asthma in
adults In the airway, both extracellular and intracellular calcium stores are mobilised for smooth muscle contraction. The extracellular mobilisation is via voltage-sensitive calcium channels, while intracellular mobilisation is through receptor-operated channels. Bronchoconstrictors activate one or both types of calcium channel. Magnesium can block or compete with calcium at voltage- or receptor-operated channels, and in vitro studies have shown an inhibitory effect on constriction of bronchial smooth muscle, release of acetylcholine from nerve terminals, and on release of histamine from mast cells. Recent work in adults has shown that a magnesium effect which had been observed in severe asthmatics after intravenous magnesium sulphate is also seen after administration of the nebulised form. These data are being considered in the context of adding to the drug armamentarium in the treatment of the most severe cases and as a means to reduce the need for hospitalisation. Beta-stimulants plus ipratropium bromide have been effective, as have combinations of salbutamol, ipratropium and flunisolide - perhaps in severe cases one should consider the addition of nebulised magnesium sulphate. Read more: Lancet 2003;361:2095-6 2003;361:2114-7 Chest 2002;122:489-97 2003;123:1908-15 2002;121:1977-87 |