During recent years theophylline with ethylenediamine (aminophylline) has enjoyed considerable popularity in the treatment of angina pectoris. This drug was introduced in 1908 by Dessauer1 as a preparation which was more soluble, more effective and less likely to produce nausea than theophylline. More recently theophylline and theobromine have been linked chemically with other compounds in an attempt to imitate and improve on the properties of aminophylline. Each of these drugs has been used in angina pectoris with good results. Unfortunately, however, little exact information is available concerning the relative merits of these purine derivatives.
The available reports are based on clinical experience with the drugs.2 It has been shown3 that clinical evaluation alone gives a false impression as to the efficacy of treatment in angina, for the administration of even inert medication may be followed by clinical improvement. The purpose of the present investigation is to determine