Calculation of AQCmax: comparison of five ophthalmic fluoroquinolone solutions*

An ion-paired moxifloxacin nanosuspension eye drop provides improved prevention and treatment of ocular infection

There are numerous barriers to achieving effective intraocular drug administration, including the mucus layer protecting the ocular surface. For this reason, antibiotic eye drops must be used multiple times per day to prevent and treat ocular infections. Frequent eye drop use is inconvenient for patients, and lack of adherence to prescribed dosing regimens limits treatment efficacy and contributes to antibiotic resistance. Here, we describe an ion-pairing approach used to create an insoluble moxifloxacin-pamoate (MOX-PAM) complex for formulation into mucus-penetrating nanosuspension eye drops (MOX-PAM NS). The MOX-PAM NS provided a significant increase in ocular drug absorption, as measured by the area under the curve in cornea tissue and aqueous humor, compared to Vigamox in healthy rats. Prophylactic and treatment efficacy were evaluated in a rat model of ocular Staphylococcus aureus infection. A single drop of MOX-PAM NS was more effective than Vigamox, and completely prevented infection. Once a day dosing with MOX-PAM NS was similar, if not more effective, than three times a day dosing with Vigamox for treating S. aureus infection. The MOX-PAM NS provided increased intraocular antibiotic absorption and improved prevention and treatment of ocular keratitis, and the formulation approach is highly translational and clinically relevant.

Pharmacokinetics of Azithromycin, Levofloxacin, and Ofloxacin in Rabbit Extraocular Tissues After Ophthalmic Administration

INTRODUCTION

Azithromycin demonstrates high tissue distribution and prolonged elimination half-life. In this study, we monitored the pharmacokinetics of a single ophthalmic administration of 1% azithromycin ophthalmic solution containing polycarbophil in the extraocular tissues, including the eyelid, and compared it with that of two commercial ophthalmic products, 1.5% levofloxacin ophthalmic solution and 0.3% ofloxacin ophthalmic ointment.

METHODS

Rabbits were treated with either a single topical administration of 1% azithromycin ophthalmic solution, 1.5% levofloxacin ophthalmic solution, or 0.3% ofloxacin ophthalmic ointment. The eyelid, conjunctiva, and cornea were collected at 0.25, 0.5, 1, 2, 4, 8, and 24 h post-administration. Tissue samples were pretreated for drug concentration measurements by ultra-performance liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were determined by non-compartmental analysis.

RESULTS

Azithromycin was rapidly absorbed, and its levels remained near the observed maximum concentrations for up to 24 h post-administration in all tissue. In contrast, extraocular tissue concentrations of levofloxacin and ofloxacin decreased with time. The maximum concentrations of azithromycin, levofloxacin, and ofloxacin were 35.6, 34.1, and 55.1 µg/g in the eyelid, 44.2, 46.8, and 20.4 µg/g in the conjunctiva, and 79.9, 18.0, and 2.21 µg/g in the cornea, respectively. The values of the area under the curve from 0 to 24 h after administration of azithromycin, levofloxacin, and ofloxacin were 602, 58.5, and 267 µg·h/g in the eyelid, 837, 43.2, and 51.9 µg·h/g in the conjunctiva, and 1250, 26.4, and 5.46 µg h/g in the cornea, respectively.

CONCLUSION

The drug concentrations of azithromycin and levofloxacin were relatively comparable among the extraocular tissues following topical administration of the respective ophthalmic solutions, whereas the concentrations of ofloxacin varied following dosing of its ophthalmic ointment. The slow elimination profile in any extraocular tissue of rabbits was unique to azithromycin, and led to the demonstration of high exposures of azithromycin in all extraocular tissues after ophthalmic administration.

FUNDING

This research and Rapid Service Fees were supported by Senju Pharmaceutical Co., Ltd.

Impact of Topically Administered Steroids, Antibiotics, and Sodium Hyaluronate on Bleb-Related Infection Onset: The Japan Glaucoma Society Survey of Bleb-Related Infection Report 4

Purpose

To investigate the impact of topically administered ophthalmic medications on the onset and severity of bleb-related infections.

Methods

Data obtained from 104 eyes of 104 patients with bleb-related infections were analyzed. We assigned an infection stage to each eye (stage 1-4) and analyzed the onset severity.

Results

Steroids and antibiotics were routinely administered to 13 (12.5%) and 42 (40.4%) eyes, respectively. The median stage of steroid-administered eyes was 3 versus 1 for eyes without steroid administration (P = 0.012). The median duration from surgery to infection for the steroid-administered eyes was 2.0 years versus 5.8 years for eyes without steroid administration (P = 0.030). The median duration from surgery to infection for the antibiotic-administered eyes was 6.4 years versus 3.9 years for eyes without antibiotic administration (P = 0.025). Multiple logistic regression analysis revealed that infections were severe in the steroid-administered eyes (odds ratio: 4.57). No infections developed within 16 weeks postoperatively. No relationship was detected between sodium hyaluronate and the analyzed factors.

Conclusions

Topical steroid administration beyond the immediate postoperative period may affect severe and earlier onset bleb-related infections. Conversely, topical antibiotic administration may be effective in suppressing earlier onset bleb-related infections.

Toxicity of Intracameral Injection of Fourth-Generation Fluoroquinolones on the Corneal Endothelium

PURPOSE

The aim of this study was to compare the cellular susceptibility patterns and morphologic changes in the corneal endothelium associated with the use of fourth-generation fluoroquinolones.

METHOD

Endothelial susceptibility was assessed through intracameral injection of besifloxacin, gatifloxacin, and moxifloxacin. Human umbilical vein endothelial cells (HUVECs) were used as the standard cellular lineage to assess the quantitative toxicity of each antibiotic solution. Qualitative changes in the morphologic character of the corneal structure and the endothelial layer were generated using a combination of ex vivo and in vivo assays. Experimental assays were conducted in triplicate, and the results were statistically analyzed.

RESULTS

At 1 hour of exposure, all HUVECs exposed to antibiotics showed viability above 85%, after 3 hours of exposure to besifloxacin, gatifloxacin, and moxifloxacin, the percentages of viable cells were 68.3 ± 4.0 (P < 0.001), 90.7 ± 4.2 (P < 0.05), and 93.3 ± 1.5 (P > 0.05), respectively. All fluoroquinolones tested showed toxicity to HUVECs, resulting in significant (P < 0.001) loss of cellular viability after 24 hours of drug exposure. Giant endothelial cells were observed in animals treated with the 3 fluoroquinolones in contrast to the absence of these abnormal cells in the untreated group. Early cellular detachment was seen in the endothelial layer after exposure to gatifloxacin and moxifloxacin.

CONCLUSIONS

We concluded that injection of fourth-generation fluoroquinolones in the aqueous humor did not adversely affect the corneal endothelium. However, these results suggested that prophylactic intracameral injection of besifloxacin, gatifloxacin, or moxifloxacin, if needed, should be administered as a last therapeutic resource in clinical practice, with careful and constant monitoring of corneal endothelium.

Comprehensive evaluation of formulation factors for ocular penetration of fluoroquinolones in rabbits using cassette dosing technique

OBJECTIVE

Corneal permeability of drugs is an important factor used to assess the efficacy of topical preparations. Transcorneal penetration of drugs from aqueous formulation is governed by various physiological, physiochemical, and formulation factors. In the present study, we investigated the effect of formulation factors like concentration, pH, and volume of instillation across the cornea using cassette dosing technique for ophthalmic fluoroquinolones (FQs).

MATERIALS AND METHODS

Sterile cocktail formulations were prepared using four congeneric ophthalmic FQs (ofloxacin, sparfloxacin, pefloxacin mesylate, and gatifloxacin) at concentrations of 0.025%, 0.5%, and 0.1%. Each formulation was adjusted to different pH ranges (4.5, 7.0, and 8.0) and assessed for transcorneal penetration in vivo in rabbit's cornea (n=4 eyes) at three different volumes (12.5, 25, and 50 μL). Aqueous humor was aspirated through paracentesis after applying local anesthesia at 0, 5, 15, 30, 60, 120, and 240 minutes postdosing. The biosamples collected from a total of 27 groups were analyzed using liquid chromatography-tandem mass spectroscopy to determine transcorneal permeability of all four FQs individually.

RESULTS

Increase in concentration showed an increase in penetration up to 0.05%; thereafter, the effect of concentration was found to be dependent on volume of instillation as we observed a decrease in transcorneal penetration. The highest transcorneal penetration of all FQs was observed at pH 7.0 at concentration 0.05% followed by 0.025% at pH 4.5. Lastly, increasing the volume of instillation from 12.5 to 50 μL showed a significant fall in transcorneal penetration.

CONCLUSION

The study concludes that formulation factors showed discernible effect on transcorneal permeation; therefore, due emphasis should be given on drug development and design of ophthalmic formulation.

Moxifloxacin as postoperative prophylaxis for Enterococcus faecalis-induced endophthalmitis after cataract surgery in aphakic rabbits

PURPOSE

The development of endophthalmitis after cataract surgery often results in significant vision loss. Inhibition of bacterial proliferation in the anterior chamber using antibiotic eye drops is important to prevent endophthalmitis after cataract surgery. We aimed to determine the sensitivity of fluoroquinolones against Enterococcus faecalis ocular isolates and the efficacy of fluoroquinolones to prevent E. faecalis-induced endophthalmitis in aphakic rabbits.

METHODS

The minimum inhibitory concentrations (MICs) of moxifloxacin (MFLX) and levofloxacin (LVFX) used in ophthalmic solutions for 13 E. faecalis isolates obtained from the conjunctival sac or endophthalmitis cases were determined. Eye drops containing MFLX (0.5%), LVFX (0.5%), or saline were administered to aphakic rabbits with endophthalmitis induced by E. faecalis. The eye drops were administered immediately after lensectomy and at 3 and 6 h after cataract surgery (early instillation group) or immediately after lensectomy and at 12 and 15 h after cataract surgery (delayed instillation group). Bacterial growth, electroretinography (ERG), and slit-lamp examination (SLE) were determined throughout the course of infection.

RESULTS

In vitro susceptibility testing revealed that the MICs of MFLX for E. faecalis isolates were lower than those of LVFX. In the early ocular instillation groups, MFLX significantly improved SLE scores, ERG, and viable bacterial counts compared with LVFX and saline (all, P<0.05). There were no significant differences in any parameter between MFLX and saline in the delayed ocular instillation groups.

CONCLUSIONS

Early ocular instillation of MFLX delays retinal damage compared with LVFX when used to treat E. faecalis-induced endophthalmitis after cataract surgery.

Comparison of corneal and aqueous humor penetration of moxifloxacin, gatifloxacin and levofloxacin during keratoplasty

INTRODUCTION

Achieving high antibiotic concentrations is important for preventing and treating postoperative infections. However, no study has simultaneously compared the achieved concentrations of moxifloxacin, gatifloxacin, and levofloxacin in the human cornea and aqueous humor. The authors therefore performed a randomized study to determine the concentrations of 0.5% moxifloxacin, 0.3% gatifloxacin, and 0.5% levofloxacin in the corneal tissue and aqueous humor after topical instillation in patients undergoing penetrating keratoplasty.

METHODS

Patients who required penetrating keratoplasty were eligible for this study. The topical preparations of 0.5% moxifloxacin, 0.3% gatifloxacin, and 0.5% levofloxacin used in the study were preservative free (Japanese formulations). Patients were randomly assigned to one of three sequential drug groups, in which each drug was administered three times before surgery. In each administration cycle, the patients received two drops of each drug at 2-minute intervals. Samples of corneal tissue and aqueous humor were collected during surgery. The concentrations of each drug in the samples were determined by high-performance liquid chromatography.

RESULTS

A total of 63 patients across eight centers in Japan were enrolled in the study. Overall, 61 corneal and 58 aqueous humor samples were evaluated. The concentration (mean±standard deviation) of moxifloxacin in corneal tissues was 12.66±8.93 μg/g, which was significantly higher than that of gatifloxacin (4.71±3.39 μg/g; P<0.0001) and levofloxacin (5.95±4.02 μg/g; P<0.0001). The mean concentration of moxifloxacin in aqueous humor samples was 1.40±1.17 μg/mL, which was significantly higher than that of gatifloxacin (0.65±0.80 μg/mL; P=0.0001) and levofloxacin (0.89±0.86 μg/mL; P<0.05). The sequence of drug administration did not significantly affect the results.

CONCLUSION

These results show that 0.5% moxifloxacin achieved superior ocular concentration than both 0.3% gatifloxacin and 0.5% levofloxacin.

Topical ophthalmic moxifloxacin elicits minimal or no selection of fluoroquinolone resistance among bacteria isolated from the skin, nose, and throat

PURPOSE

To investigate whether moxifloxacin therapy of bacterial conjunctivitis in children changes the moxifloxacin susceptibility of bacterial isolates in eyes, cheeks below eyes, nares, and throat.

METHODS

Patients (age: 1 to 12 years, n = 105) with bacterial conjunctivitis were treated topically with moxifloxacin three times a day for 7 days. Gender- and age-matched subjects with normal eyes (age: 1 to 12 years, n = 57) served as the control group. Microbiological specimens were collected on days 1 (prior to therapy), 8 (1 day after end of therapy), and 42 (follow-up). Specimens were processed to recover total bacteria and bacteria that grew on fluoroquinolone-selective media. Bacteria were identified to the species level and susceptibility to moxifloxacin and selected other antibiotics determined.

RESULTS

The primary pathogens recovered from the infected eyes on day 1 before therapy were Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus. None of the pre-therapy isolates of H. influenzae and S. pneumoniae were resistant to moxifloxacin. Isolates of these two pathogenic species were also recovered primarily from the nose and eyes. Moxifloxacin-resistant S. aureus isolates (minimum inhibitory concentration 1.0 μg/mL or greater) were recovered from the nose and throat prior to topical dosing on day 1. However, there was no change in the frequency of moxifloxacin-resistant isolates of S. aureus following treatment with moxifloxacin.

CONCLUSION

Treatment of conjunctivitis with topical ophthalmic moxifloxacin did not select for moxifloxacin resistance in H. influenzae, S. pneumoniae, or S. aureus in the eye or distal body sites.

Intraocular penetration of sequentially instilled topical moxifloxacin, gatifloxacin, and levofloxacin

Purpose:

The objective of the study was to compare the intraocular penetration levels of the newer fluoroquinolones, moxifloxacin, gatifloxacin, and levofloxacin in the rabbit’s cornea, aqueous humor, and conjunctiva after topical instillation.

Methods:

0.5% moxifloxacin, 0.3% gatifloxacin, and 0.5% levofloxacin were instilled in random sequence in both eyes of nine New Zealand White rabbits at two-minute intervals. Instillation was repeated every 15 minutes for a total of three drops of each fluoroquinolone per eye. Three additional animals had only moxifloxacin instilled bilaterally using the same schedule. Sixty minutes after the final instillation, the rabbits were sacrificed for determination of corneal, aqueous humor, and conjunctival fluoroquinolone concentrations using high-performance liquid chromatography.

Results:

Moxifloxacin achieved significantly higher concentrations than levofloxacin and gatifloxacin in the cornea (P = 0.0102 and P = 0.0006, respectively), aqueous humor (P = 0.0015 and P < 0.0001, respectively), and conjunctiva (P = 0.0191 and P = 0.0236, respectively).

Conclusions:

0.5% moxifloxacin eyedrops provided superior intraocular penetration in rabbits’ eyes compared with the two other fluoroquinolones, 0.5% levofloxacin and 0.3% gatifloxacin.