Fluoroquinolone antibacterial eye drops: effects on normal human corneal epithelium, stroma, and endothelium

Structural Characterization of the Millennial Antibacterial (Fluoro)Quinolones-Shaping the Fifth Generation

The evolution of the class of antibacterial quinolones includes the introduction in therapy of highly successful compounds. Although many representatives were withdrawn due to severe adverse reactions, a few representatives have proven their therapeutical value over time. The classification of antibacterial quinolones into generations is a valuable tool for physicians, pharmacists, and researchers. In addition, the transition from one generation to another has brought new representatives with improved properties. In the last two decades, several representatives of antibacterial quinolones received approval for therapy. This review sets out to chronologically outline the group of approved antibacterial quinolones since 2000. Special attention is given to eight representatives: besifloxacin, delafoxacin, finafloxacin, lascufloxacin, nadifloxacin and levonadifloxacin, nemonoxacin, and zabofloxacin. These compounds have been characterized regarding physicochemical properties, formulations, antibacterial activity spectrum and advantageous structural characteristics related to antibacterial efficiency. At present these new compounds (with the exception of nadifloxacin) are reported differently, most often in the fourth generation and less frequently in a new generation (the fifth). Although these new compounds' mechanism does not contain essential new elements, the question of shaping a new generation (the fifth) arises, based on higher potency and broad spectrum of activity, including resistant bacterial strains. The functional groups that ensured the biological activity, good pharmacokinetic properties and a safety profile were highlighted. In addition, these new representatives have a low risk of determining bacterial resistance. Several positive aspects are added to the fourth fluoroquinolones generation, characteristics that can be the basis of the fifth generation. Antibacterial quinolones class continues to acquire new compounds with antibacterial potential, among other effects. Numerous derivatives, hybrids or conjugates are currently in various stages of research.

Effects of Fluoroquinolone-Based Antibacterial Ophthalmic Solutions on Corneal Wound Healing

PURPOSE

To evaluate the effects of fluoroquinolone-based antibacterial ophthalmic solutions on cell proliferation in vitro and corneal wound healing in vivo.

METHODS

Staten's Serum institute rabbit corneal cells were exposed to phosphate-buffered saline, 1.5% and 0.5% levofloxacin, 0.5% moxifloxacin, and 0.3% gatifloxacin, for 2 min, following which the cells were incubated without the drug. The cell viability was evaluated after 24 or 72 h of incubation. Rabbit corneal epithelial abrasion models created using n-heptanol were instilled with saline or fluoroquinolone-based solutions 7 times at 30-min intervals, following which corneal epithelial wound healing was evaluated from 30 min to 48 h by the measurement of electrical corneal resistance (CR) ratios.

RESULTS

The cell viability decreased over time; the lowest values were observed with 1.5% levofloxacin. Significant differences in cell viability were observed among the 4 solutions at 72 h (P<0.05); the cell viabilities of 1.5% and 0.5% levofloxacin, 0.5% moxifloxacin, and 0.3% gatifloxacin were 21.6%, 97.9%, 39.1%, and 67.5%, respectively. The electrical CR ratios at 48 h after instillation were 103.8% (saline), 78.2% (1.5% levofloxacin), 105.0% (0.5% levofloxacin), 74.9% (0.5% moxifloxacin), and 87.7% (0.3% gatifloxacin); the difference was significant between 1.5% levofloxacin or 0.5% moxifloxacin and saline (P<0.05).

CONCLUSIONS

The cytotoxicities of 1.5% and 0.5% levofloxacin, 0.5% moxifloxacin, and 0.3% gatifloxacin were different, and 1.5% levofloxacin and 0.5% moxifloxacin resulted in delayed corneal wound healing. The results suggest that 1.5% levofloxacin exerts the greatest influence on corneal wound healing.

Upregulation of P-glycoprotein expression by ophthalmic drugs in different corneal in-vitro models

OBJECTIVES

The purpose of this study was to analyse P-glycoprotein (P-gp) expression in different human in-vitro cornea models (HCE-T epithelial model and Hemicornea construct) after stimulation with P-gp substrates (rhodamine 123, levofloxacin and acebutolol).

METHODS

The influence of P-gp substrates on mRNA expression was analysed using reverse transcriptase polymerase chain reaction (PCR) and real-time PCR. The effect of stimulation on the transporter functionality was estimated with a digoxin efflux assay. The Caco-2 cell line was used as positive control.

KEY FINDINGS

The reverse transcriptase PCR results showed an increase in band intensity compared with the control medium for all substrates. The real-time PCR for the Caco-2 and HCE-T epithelial model yielded a similar outcome, in which all tested substrates upregulated P-gp. In contrast, the Hemicornea construct showed no significant increase in the mRNA expression after stimulation. Both in-vitro models possessed similar drug transport profiles after stimulation. A significantly increased efflux of digoxin was measured after 24 and 72 h of stimulation with levofloxacin and acebutolol.

CONCLUSIONS

The expression and functionality of the P-gp in corneal tissue can be influenced through time exposure with specific substrates. However, the exact mechanism still requires further elucidation.

Epithelial wound healing after cataract surgery comparing two different topical fluoroquinolones

PURPOSE

To compare the epithelial wound healing response of two preservative-free fluoroquinolones, moxifloxacin and levofloxacin, in patients who underwent cataract surgery.

MATERIALS AND METHODS

In this prospective, evaluator-masked, randomized clinical trial, 59 eyes of 50 patients who underwent cataract surgery were enrolled. Patients were randomized to receive moxifloxacin 0.5% (n=32 eyes) or levofloxacin 0.5% (n=27 eyes). All patients instilled moxifloxacin or levofloxain four times daily for 1 week prior to surgery and 2 weeks after surgery. The epithelial wound healing status in the corneal incision site was scanned with a raster scan mode of fourier-domain optical coherence tomography (FD-OCT). The number of eyes showing epithelial defect images and average number of corneal epithelial defect cuts per eye were compared between groups. All patients were evaluated on postoperative days 1, 2, 3, and 10.

RESULTS

On postoperative days 1, 2, and 3, the number of eyes showing epithelial defects in FD-OCT was not statistically different (all p>0.05). The average number of corneal epithelial defect cuts was also not statistically different between the two groups (all p>0.05). No eyes showed epithelial defects on postoperative day 10 in either group.

CONCLUSION

There were no differences on epithelial wound healing comparing these two different fluoroquinolones at the incision site of cataract surgery.