This section is from the "A Handbook of Useful Drugs" book, by State Medical Examining and Licensing Boards.
Properties : Magnesium sulphate occurs as small, colorless prismatic needles or rhombic prisms, without odor, and having a cooling, saline and bitter taste. It is freely soluble in water, but practically insoluble in alcohol.
Action and Uses: Magnesium sulphate is one of the most active of the saline cathartics. When injected intravenously or intramuscularly it depresses the nervous and muscular structures, but the absorption from the alimentary canal is too slight to produce these effects. It has been injected for the purpose of producing spinal anesthesia, but its action is too uncertain and dangerous for use in man. It has been used in a few cases by injections in the subarachnoid space for the relief of tetanus.
Concentrated solutions of magnesium sulphate have been widely used as local applications in various inflammations, such as sprains, burns, erysipelas and the like, with asserted beneficial results.
Dosage: 15 gm. or 240 grains. Magnesium sulphate may be dissolved so that 1 c.c. of the solution contains 1 gm. of the salt, and of this solution 5 c.c. are given hourly until a laxative action is secured. This dose should be followed by sufficient water to dilute the salt.