Antigenicity of the new quinolone antibacterial agent levofloxacin

An antigenicity study of a new quinolone antibacterial agent, (-)-(S)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo- 7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid hemihydrate (lefovloxacin, DR-3355, CAS 100986-85-4), was carried out in mice, guinea pigs and rabbits with passive cutaneous anaphylaxis (PCA), systemic anaphylaxis (SA) and enzyme linked immunosorbent assay (ELISA). Mice were sensitized with DR-3355 (1-100 mg/kg) or DR-3355-ovalbumin (OA) conjugate (DR-3355-OA; 500 micrograms/kg). No IgE antibodies to DR-3355 were detected in the sera obtained from the DR-3355-sensitized mice, indicating that DR-3355 has no immunogenicity in mice. By using DR-3355-OA as a sensitizing antigen, DR-3355-specific IgE was produced successfully in 7 out of 10 sera, and 4 sera showed positive responses in 24-h PCA on intravenous injection of DR-3355 (40 mg/kg). These responses disappeared on challenge with a dose of 2.5 mg/kg. Guinea pigs or rabbits were sensitized with DR-3355 (2-100 or 2-20 mg/kg) or DR-3355-OA (2 mg/kg). No SA was observed in the sensitized guinea pigs after the intravenous injection of DR-3355 (40 mg/kg). No antibodies to DR-3355 were detected in the sera obtained from the sensitized guinea pigs and rabbits by PCA or ELISA. These results suggest that DR-3355 may not possess antigenicity in guinea pigs and rabbits. On the other hand, the results of PCA in mice suggest that DR-3355 may have eliciting antigenicity potential.