CONCENTRATIONS OF DOXYCYCLINE AND PENICILLIN-G IN SERA AND CEREBROSPINAL-FLUID OF PATIENTS TREATED FOR NEUROBORRELIOSIS

Concentrations of doxycycline and penicillin G in serum and cerebrospi nal fluid (CSF) were analyzed in 36 patients during treatment for neur oborreliosis. Twenty patients were treated intravenously with penicill in G at 3 g every 6 h (q6h), and 26 patients were treated orally with doxycycline at 200 mg q24h. All samples were collected on day 13 of tr eatment. The median concentrations of penicillin G in serum were 0.5, 37, and 5.6 mu g/ml before and 1 and 3 h after drug administration, an d that in CSF was 0.5 (range, 0.3 to 1.6) mu g/ml after 2 to 3 h. The median concentrations of doxycycline in serum were 2.1, 6.1, and 4.7 m u g/ml before and 2 and 6 h after drug administration, and that in CSF was 0.6 (range, 0.4 to 2.5) mu g/ml after 4 h. All patients had conce ntrations of penicillin G or doxycycline in CSF above the lowest repor ted MICs of penicillin G (0.003 mu g/ml) and doxycycline (0.12 mu g/ml ) for Borrelia burgdorferi. However, no patients had a drug concentrat ion in CSF above the highest reported MIC of penicillin G (8 mu g/ml), and only one had a drug concentration in CSF above the highest report ed MIC of doxycycline (2 mu g/ml), despite good clinical response to t reatment. No treatment failure or relapse was observed during a 1-year follow-up, although one patient treated with penicillin G and one tre ated with doxycycline were retreated because of residual pain. The cho sen dosages of penicillin G and doxycycline seem to give sufficient co ncentrations in serum and CSF for the treatment of neuroborreliosis.