Reversed-phase high-performance liquid chromatographic determination of enoxacin and 4-oxo-enoxacin in human plasma and prostatic tissue. Application to a pharmacokinetic study.
A simple high-performance liquid chromatographic method has been developed for the simultaneous determination of enoxacin and 4-oxo-enoxacin in plasma and prostatic tissue. The work-up procedure involves a liquid-liquid extraction step followed by isocratic chromatography on a reversed-phase analytical column, with ultraviolet absorbance detection (lambda = 340 nm). Using a mobile phase of 20.9% (v/v) acetonitrile buffer (pH 2.1), adequate retention time and separation among the analytes has been obtained using tetrabutylammonium hydroxide included in the eluent. Retention times are 5.2 min for enoxacin, 6.8 min for pefloxacin and 12 min for 4-oxo-enoxacin. For plasma and prostatic tissue, the precision of the assay was below 9%. The percent recovery from the nominal values for accuracy ranged from 94 to 108%. The limits of quantitation were 20 ng/ml for plasma and 50 ng/g for tissue (precision < 18%). The detection limits were 10 ng/ml and 25 ng/g, respectively. The calibration curves were linear from 20 to 1000 ng/ml for plasma and from 50 to 2500 ng/g for tissue. In plasma, the extraction recoveries averaged 52% for enoxacin and 63% for 4-oxo-enoxacin. In prostatic tissue, they were 57 and 76% for the two analytes, respectively. This method has been employed for the determination of enoxacin and 4-oxo-enoxacin in plasma and prostatic tissue samples from patients following repeated oral administration of enoxacin (400 mg twice a day for four days).
Hamel
B
B
Laboratoire de Pharmacocinétique, Faculté de Pharmacie, Montpellier, France.
Audran
M
M
Costa
P
P
Bressolle
F
F
D000236:Adenoma / Q000378:metabolism / Q000601:surgery; D000890:Anti-Infective Agents / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics; D001682:Biological Availability; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D015365:Enoxacin / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood / Q000493:pharmacokinetics; D006801:Humans; D007202:Indicators and Reagents; D008297:Male; D011467:Prostate / Q000737:chemistry*; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000601:surgery; D012997:Solvents
D000890:Anti-Infective Agents; D007202:Indicators and Reagents; D012997:Solvents; D015365:Enoxacin; C049814:4-oxo-enoxacin