Capillary Zone Electrophoretic Determination of Tosufloxacin and Trovafloxacin in Urine J. L. Vflchez/L. Araujo 1/A. Prieto 2 /A. Naval6n* Department of Analytical Chemistry, Facultyof Sciences, University of Granada, Avda. Fuenten ueva s/n, 18071 Granada, Spain; E-Maih anavalon@ugr.es 1 Current address: Facultyof Engineering, University of Zuha, PO Box 10259, Maracaibo, Venezuela 2 Current address: Facultyof Agronomy, University ofZuha, PO Box 6610, Maracaibo, Venezuela Key Words Capillary zone electrophoresis Tosufloxacinand trovafloxacin Antibacterials Urine samples Summary A simple and rapid capillaryzone electrophoretic method with UV detection has been devel- oped for determination of tosufloxacin and trovafloxacin. The separation was performed in fused-silica capillaries (57 cm length x 75 I~m i.d.); the running bufferwas 35 mM borate + 35 mM phosphate buffer solution, pH 8.6, containing 6% (v/v) acetonitrile. The applied poten- tial was 15 kV, the temperature 30 ~ and detection was at 262 nm. Piromidic acid was used as the internal standard. Response was linearly dependent on concentration in the range 1.0- 120.0 I~g mL 1 and the detection hmitwas 0.2 I~g mL 1 for both compounds.The analy- sis was highly reproducible (RSD bel',,veen 3.41 and 1.25%). The method was applied to the determination of tosufloxacin and trovafloxacin in human and rat urine. The method was vali- dated by using HPLC as a reference method. Recoverywas bel',,veen 96.8 and 102%. Introduction In the last decade the fluoroquinolones have emerged as one of the most important classes of antibiotic [1]. These synthetic antimicrobial agents have broad-spectrum activity against many pathogenic gram- negative and gram-positive bacteria both in vitro and in vivo [2]. They act by inhibit- ing the DNA gyrase, resulting in bacterial death [3]. Tosufloxacin, 7-(3-amino-l-pyr- rolidinyl)-l-(2,4-difluorophenyl)-6-fluoro- 1,4-dihydro-4-oxo-l,8-naphthyridine-3- carboxylic acid (Figure 1), is a new anti- bacterial fluoroquinolone agent used in the treatment of urinary and respiratory tract infections and soft tissue and enteric infections [4, 5]. Trovafloxacin, (l~,5~,6~)- 7-(6-amino-3-azabicyclo[3.1.0] hex-3-yl)- 1-(2,4-difluorophenyl)-6-fluoro-l,4-dihy- droxy-4-oxo- 1,8-naphthyridine-3 car- boxylic acid (Figure 1), another new fluoroquinolone, is used to treat skin complaints, respiratory-tract infections, sexually transmitted diseases, and me- ningitis [6]. Recommended oral doses of trovafloxacin are 200 300mg day 1 for 7 14 days once daily [6]; for tosufloxacin oral medication is approximately 150 mg three times a day for 14 days [7]. The widespread use of these com- pounds and the need for clinical and phar- macological study require fast and sensi- tive analytical techniques for determina- tion of the presence of the drugs in biologi- cal fluids. As far as we are aware only high-performance liquid chromatogra- phic (HPLC) methods have been reported for determination of the presence of tosu- floxacin and trovafloxacin in biological fluids [8 11]. Capillary electrophoresis (CE), which is highly efficient and uses less solvent than HPLC, separates sample components according to size and charge. The resolution of CE procedures is greater than that of HPLC and the precision is of the same order. CE is less costly than HPLC and requires only modest quanti- ties of sample. The concentration sensitiv- ity of UV-visible absorbance detection in CE is, however, relatively poor compared with that in HPLC. CE has become an ad- vanced analytical methods for drug analy- sis in pharmaceutical, therapeutic, diag- nostic, and forensic applications [12]. Re- liable and automated CE instruments are commercially available and have pro- moted the exploration of an increasing number of CE methods for drug analysis inseveralmatrixes [13 17]. Although many CE methods have been used for analysis of antibiotics [18], little attention has been devoted to the separa- tion of quinolone antibiotics. CE has been used to determine ciprofloxacin in phar- maceutical formulations [19] and for the enantioselective separation of ofloxacin and DU-6859 [20]. Sun and Wu [21] deter- mined seven quinolone antibiotics by CE in pharmaceutical formulations. Although Original 0009-5893/00/02 Chromatographia 2002, 56, September (No. 5/6) 351- 06 $ 03.00/0 9 2002 Friedr. Vieweg & Sohn Verlagsgesellschaft mbH 351