| Bacterial keratitis is a kind of ocular inflamed disease which is often met clinically and even can lead to blindness. In 1960s, bacterial keratitis took the first place in all kinds of keratitis. With the improvement of living conditions and the invents of new anti-bacterial drugs, the rate of bacterial keratitis has decreased to the second place since 1980s. But this disease is still a danger for eye health and vision. The pathogens often causing bacterial keratitis are staphylococcus epidermidis, staphylococcus aureus, streptococcus pneumoniae, pseudomonas aeuroginosa and escherichia coli. Fluoroquinolones have been used in clinics for 10 years, and which have been the most often applied for more broader anti-bacterial spectrum and more poweful anti-bacterial action to G" including pseudomonas aeuroginosa and G+ in part. Levofloxacin is a new kind of fluoroquinolones which is L-isomer of ofloxacin. The anti- bacterial spectrum of levofloxacin is more broader than the former generation of fluoroquinolones, and the anti- bacterial power is two times than that of ofloxacin. G+ including anaerobic bacterial and G" are all sensitive to levofloxacin. The ocular penetration of levofloxacin is high in documents from different writers. But the ocular bioavailability of common eye-drops topically applied is low and the residence time is short, because the concentration is decreased quikly with the tear turn-over and nasolacrimal duct excretion. In order to increase ocular bioavailability and make theresidence time longer, some viscous expient was added to the common eye-drops. With the increased drug viscosity, the ocular residence time will be longer, the ocular bioavailability will be increased. Sodium hyaluronate (SH) is a high molecular weight, naturally occurring glycosaminoglycan. Sodium hyaluronate, as an additive to ophthalmic formulations, has been claimed to increase the ocular residence time. An addition of sodium hyaluronate to 0.3% levofloxacin is expected to increase the drug treatment effect.In this experiment, we used the high-performance liquid chromatograph to assay and compare the concentration changes in tears, corneas and aqueous humors after 0.3% levofloxacin-SH and 0.3% levofloxacin topically applied to rabbits eyes, and investigated the ocular pharmacokinetics and bioavailability in order to supply data for chosing much longer residence time, much stronger penetration anti-bacterial eye-drops for bacterial keratitis.1.The assay of levofloxacin concentration in corneas andaqueous humors by HPLCThe healthy adult white rabbits (2-3kg) were chosen as experiment animals. The chromatograph conditions: the mobile phase was 0.05mol/l acid citric- lmol/1 ammonium acetate-acetonitrile (82:1:17). The flow-rate was 1.2ml/min. Detection wavelength was 294nm. The column temperature was 40 C. Tears were acquired by using filter papers into inferior fomix of conjuctive sac in rabbits. Aqueous humors were acquired by using the 1 mi-syringe. The rabbits were killed at different times, and the eyeballs were excavated and then corneas were acquired. All corneas and aqueous humors were extracted by dichloroethane, dried by nitrogen, dissolved by mobile phase, and injected into HPLC. The chromatograpy peak of levofloxacin was isolated well from the mixed peaks potentially which interfere with that of levofloxacin by using this method. The remain time was stable. The linearity of standard curve was proved to be good(r=0.9999). The average reproducibility of cornea and aqueous humors in this assay, expressed as the percentage of related standard deviation (% RSD), was 76.47%, 76.53% respectively. The accuracy, expressed as the percentage error in the same day or the different day, was <3% forthree standard concentrations of corneas and aqueous humors.2.Ocular penetration and pharmacokinetics of levofloxaein intwo different preparations36 white healthy rabbits (2-3kg) which were divided randomly into 9 groups were used for 0.3% levofloxacin-SH and 0.3% levofloxacin respectively, and each group h...
|
PDF Full Text Request