The use of parenteral aminophylline in patients taking slow release theophylline preparations: an observation of clinical practice.

Parenteral theophylline usage was studied in 53 patients with worsening airflow obstruction who had been prescribed slow release theophylline drugs and were admitted to a hospital lacking facilities for rapid serum theophylline concentration estimation. Individual clinicians varied in their practice with respect to parenteral aminophylline, but in general its use was favoured in patients with asthma rather than simple chronic airflow obstruction. There was no significant difference in admission serum theophylline concentrations between 31 patients who were subsequently given intravenous aminophylline and 22 who were not. There was also no significant difference in admission serum theophylline concentrations between ten patients given an aminophylline bolus and an infusion, seven patients given a bolus alone and 14 patients given an infusion alone. Individual patient's serum theophylline concentrations were variable during infusions and often suboptimal. The results indicate that the use of parenteral aminophylline in patients receiving slow release theophyllines is imprecise and possibly hazardous without facilities for prompt serum theophylline concentration estimations. This facility should be available in hospitals where parenteral aminophylline is used.