<prompt> Which of the following drugs has been found to be useful in acute severe asthma?Magnesium SulphateAnti-leukotrineCromolyn SodiumCyclosporine  <response>: Ans. A Magnesium sulphateRef: Harrison 17the p1605Magnesium sulphate by i.v. or inhalational route has been used for the treatment of acute severe asthma. All other drugs mentioned in the options are used for prophylaxis of asthma. 