Aminophylline is a drug combination that contains theophylline and ethylenediamine in a 2:1 ratio. Once in the body, theophylline is released and acts as a phosphodiesterase inhibitor, adenosine receptor blocker, and histone deacetylase activator. Similar to other theophyllines, aminophylline is indicated for the treatment of lung diseases such as asthma, chronic bronchitis, and COPD. The majority of aminophylline medications are discontinued and the remaining medications on the market are in short supply.