[Effect of ofloxacin, ciprofloxacin and nalidixic acid on serum theophylline level in patients treated with methylxanthine preparations].

The effect of two new quinolones, ofloxacin and ciprofloxacin and nalidixic acid on serum theophylline level in 17 asthma patients treated with methylxanthines was evaluated. Each quinolone was administered one tablet twice daily to all patients for three days. Blood samples were taken before quinolone administration and 1 h, 3h and 5 h after taking the drug on the first day. Last sample was taken 5 h after quinolone administration on the third day of therapy. The serum theophylline concentration was determined by 3 M Theo FAST test. It was found that in the patients treated with ciprofloxacin serum theophylline level in all samples was significantly higher as compared with the control sample. In the patients receiving ofloxacin the theophylline level only 1 h after receiving the drug the increase was statistical significant. Nalidixic acid had no influence on serum theophylline concentration. As these studies show, the new quinolones should be applied with great caution in patients treated with high doses of methylxanthines or in patients with decreased methylxanthines clearance. In patients with chronic obturative diseases and pulmonary infections the safer drug would appear to be ofloxacin.