Serum Concentrations Of Cycloserine And Outcome Of Multidrug-Resistant Tuberculosis In Northern Taiwan

BACKGROUND: Therapeutic drug monitoring (TDM) has been advocated to promote the efficacy of anti-tuberculosis agents. Cycloserine (CS) is a second-line anti-tuberculosis drug whose serum concentrations in tuberculosis (TB) patients are largely unknown.OBJECTIVES: To investigate serum CS concentrations after drug ingestion in TB patients.METHODS: Multidrug-resistant 113 patients who were taking CS in a tertiary care centre in northern Taiwan between 1 April 2009 and 31 October 2009 were enrolled in the study. Serum CS concentrations were measured at 2 and 6 h after drug administration.RESULTS: Of 32 patients enrolled, 23 were males and 9 females. The mean CS dose was 8.8 +/- 1.3 mg/kg. The mean serum concentrations at 2 and 6 h were respectively 19.7 +/- 8.3 and 18.1 +/- 8.7 mu g/ml. Seven patients (22%) had serum drug concentrations that were higher at 6 h than at 2 h, 12 (38%) had peak serum concentrations within the recommended range of 20-35 mu g/ml; 18 patients (56%) had concentrations <20 mu g/ml at both 2 h and 6 h; and 2 patients (6%) had at least one measurement >35 mu g/ml.CONCLUSION: Lower than recommended serum CS concentrations and delayed absorption were common. It is essential to develop practical TDM to maintain proper serum drug concentrations.