Therapeutic drug monitoring of vancomycin in surgical patients using a validated HPLC method

BACKGROUND: . Therapeutic drug monitoring (TDM) is highly recommended for ensuring the safe and effective therapy with vancomycin. A reliable and cost-effective bioanalytical method is required for TDM as well as pharmacokinetic studies of vancomycin. MATERIALS AND METHODS: A selective, sensitive, and cost effective HPLC method was developed and validated for quantification of vancomycin concentrations in human plasma. The mobile phase was a mixture of buffer (50 mM ammonium dihydrogen phosphate, pH 2.4) and acetonitrile 88 : 12 v/v. The separation was carried on C18 column (125 × 4.6 mm, particle size 5 µm) with isocratic flow rate of 0.370 mL/min at room temperature with UV detection at 215 nm. The method was validated for sensitivity, accuracy, and precision as well as stability of vancomycin in human plasma by following European Medicine Agency (EMA) guideline. Therapeutic drug monitoring of vancomycin was performed by quantifying the trough concentrations of vancomycin in 65 human plasma samples after administration of therapeutically relevant dose. RESULTS: The developed method was sensitive enough to quantify vancomycin concentrations as low as 0.25 mg/L in human plasma. Moreover, the method was proved accurate and precise in terms of quantifying the unknown concentration of vancomycin. The evaluation of short-term, long-term, and freeze-thaw stability proved the stability of vancomycin in human plasma. The TDM of vancomycin by using this method showed that 39 (60%) samples were within the target trough concentration range (TTCR), i.e. 10 - 20 mg/L, while 23 samples (35.4%) were below the TTCR, and 3 samples (4.6%) were above this range. CONCLUSION: The developed method is sensitive and cost effective for quantification of vancomycin in human plasma. The results of sample analysis shows that the developed method can be used reliably for TDM of vancomycin.