1541. A Novel and Fast Liquid Chromatography Method for Determination of Fluoroquinolones in Human Plasma

BACKGROUND: Fluoroquinolones (FQs) are frequently used antimicrobial agents. Considering that the FQs exhibit concentration-dependent bactericidal activity, concentrations of FQs in the biological fluids must be monitored to ensure treatment success. The literature search revealed that there is no method for the determination of levofloxacin (LEV), ciprofloxacin (CIP), moxifloxacin (MOX), and gemifloxacin (GEM) in plasma up to date. Consequently, the aim of this study was to develop and validate a new high-performance liquid chromatography (HPLC) method for determination of these FQs in plasma and evaluate effects of concomitant drugs on plasma FQ concentrations of patients. METHODS: Blank plasma samples spiked with FQs were employed for method validation studies. Validation studies were conducted in accordance with the recommendations of the US FDA. In order to demonstrate feasibility of method, 5 patients with polypharmacy, receiving orally CIP, LEV, or MOX as part of their treatment were included in the study. Blood samples were collected at two different times, just before and 2 hours after the second drug administration. RESULTS: The separation of FQs was accomplished within 7.5 minutes. The method was linear in the range of 0.1–10 µg/mL with the correlation coefficient >0.99. The RSD at four concentration levels (0.1, 0.3, 4, and 8 µg/mL) was less than 7% with accuracy in the range of 91.8–111.9%.The method was applied to the determination of CIP, LEV, and MOX levels in plasma samples of 5 patients with polypharmacy. Determined CIP and LEV levels were in accordance with literature. On the other hand, MOX concentration 2 hours after administration in plasma of one patient was found to be 6.1 ± 0.1 µg/mL which was higher than previously reported maximum plasma concentration of MOX (4.5 µg/mL). The patient had hypoalbuminemia and MOX is approximately 50% bound to serum proteins. Due to low level of albumin, the level of free MOX in plasma may be increased. CONCLUSION: A simple, fast, and reliable HPLC method was developed and validated for the determination of LEV, CIP, MOX, and GEM in plasma. It is suitable therapeutic drug monitoring of these FQs and can be applied to other pharmacokinetic and toxicological studies. DISCLOSURES: All authors: No reported disclosures.