Effects of intravenous theophylline, aminophylline and ethylenediamine on antigen-induced bronchoconstriction in guinea pigs.

The antiasthmatic effect of i.v. injection of theophylline was compared with that of aminophylline by using an antigen-induced bronchoconstriction model in sensitized guinea pigs. Both theophylline and aminophylline showed dose-dependent inhibition of antigen-induced bronchoconstriction. Statistically significant differences were observed at theophylline doses of 20 and 40 mg/kg and at aminophylline doses of 25 and 50 mg/kg. Thus, antiasthmatic effects of both drugs appeared to be similar. In addition, intravenous ethylenediamine did not influence either airflow in normal guinea pigs or bronchoconstriction induced by antigen at doses up to 30 mg/kg. In conclusion, the ethylenediamine in aminophylline may not influence the antiasthmatic action of theophylline, and the therapeutic effects of theophylline and aminophylline are suggested to be similar.