THE EFFECTS OF THEOPHYLLINE ON SERUM ALPRAZOLAM LEVELS

Theophylline and benzodiazepines are frequently combined in clinical p ractice. Because of a number of case reports about antagonism of benzo diazepine-induced sedation by theophylline, we investigated serum alpr azolam levels in a convenient sample of pulmonary medicine inpatients receiving theophylline and no theophylline. One mg of alprazolam was g iven daily for seven days to 6 patients receiving theophylline and 7 p atients not receiving theophylline treatment. On days 2 through 7, tro ugh serum alprazolam levels were measured. On day 7, blood samples wer e collected before (0 hour), and at 3, 6, 9 and 12 hours after alprazo lam administration. In patients receiving theophylline, serum trough a lprazolam levels were significantly lower during each day of the study . In patients receiving no theophylline, serum alprazolam levels were in the therapeutic range, except for two patients who had high alprazo lam levels. In this small study, serum alprazolam levels were found to be consistently below the therapeutic range in patients receiving chr onic theophylline treatment. Previously reported antagonism of anxioly tic effects of benzodiazepines by theophylline is probably due to the lower serum benzodiazepine levels in these patients.