1992 Volume 40 Issue Supplement3 Pages 196-202
The serum concentraion profile and renal handling of ofloxacin (OFLX), which is a 1:1 mixture of optical isomers, and levofloxacin (LVFX, DR-3355), which is the pure l-isomer of OFLX, were investigated by simultaneous quantitative analysis of both isomers with HPLC in seven healthy male volunteers. Each subject was orally administered three test drugs over a three-week period in the order of LVFX 100mg, OFLX 200mg, and LVFX 100mg+OFLX 200mg as a cross-over study. Each drug was administered once with a one-week washed period before administering the next drug. Only the l-isomer was detected in both the serum and urine after LVFX administration.
Similar concentrations of the d-isomer and l-isomer were observed in both the serum and urine at each sampling point after OFLX ingestion.
In the case of coadministration of LVFX and OFLX, the concentration of the l-isomer was always two times higher than that of the d-isomer in both serum and urine. These results are a reflection of the administered dose of each isomer. Therefore, interconversion of the d-isomer and l-isomer in the body can be neglected.
The area under the serum concentration-time curves, the mean residence times and the total body clearances of both isomers after three different doses suggest that the biological fates of both isomers are the same in humans.
The renal clearance values and quantitative investigation of renal handling of both isomers, i. e., separate investigation of glomerular filtration, renal tubular secretion and renal tubular reabsorption, also indicated the same disposition pattern.