Serum and sputum concentrations of enoxacin after single oral dosing in a clinical and bacteriological study

Fifteen patients admitted to hospital with acute purulent exacerbations of chronic bronchitis were treated with enoxacin by mouth (three 200 mg capsules twice daily) for ten days. Sputum was cultured before, during and after the treatment course. Serum and sputum concentrations were measured microbiologically at intervals on the first treatment day. Blood was assayed before, and 1, 1 1/2, 2, 2 1/2, 3, 5 and 7 h after the first dose and purulent unhomogenized sputum was tested in samples collected 0-2, 2-4, 4-6 and 6-8 h after this dose. The highest concentrations in serum were usually noted 2 or 2 1/2 h after the medication and ranged from approximately 3 to 6 mg/l (average 4.08 mg/l). The highest sputum concentrations were generally found in the 2-4 or 4-6 h portions, and ranged from 2.2 to 6 mg/l (average 3.68 mg/l). The areas under the serum and sputum concentration-time curves were both calculated to be 17.03 mg/l.h (0-7 h values) whereas the projected 0-12 h values were 25.2 and 26.9 mg/l.h, respectively. The drug concentrations declined slowly in serum and sputum with half-lives of approximately 5 and 4 h. Penetration from blood to sputum as judged on peak to peak ratios was approximately 90%, whereas the AUC value ratios showed penetration ranging from 100 to 107.5%. Unfortunately, 9 of the 15 patients had to abandon the treatment (mostly on the third day) due to unwanted drug effects (principally nausea, but some patients had hallucinations, dizziness or epileptiform attacks) possibly related to interference with theophylline metabolism.