The ocular penetration of levofloxacin 1.5% and gatifloxacin 0.3% ophthalmic solutions in subjects undergoing corneal transplant surgery

Co-delivery of metformin and levofloxacin hydrochloride using biodegradable thermosensitive hydrogel for the treatment of corneal neovascularization

Corneal neovascularization (CNV) is one of the major causes of severe disorders in ocular surface. Subconjunctival administration provides a localized and effective delivery of anti-angiogenic agents to inhibit neovascularization. In the present study, the ABA triblock copolymer of poly(D,L-lactic-co-glycolic acid)-block-poly(ethylene glycol)-block-poly(D,L-lactic-co-glycolic acid) (PLGA-PEG-PLGA) was used as a sustained drug delivery carrier for metformin (MET) and levofloxacin hydrochloride (LFH). Both drugs and PLGA-PEG-PLGA copolymers could be easily dissolved in water at low or room temperature and the mixed solution could form a drug-loaded thermosensitive hydrogel in terms of body temperature response. The in vitro release investigation displayed a sustained release of MET and LFH from the formulation for one month. The in vivo efficacy of subconjunctival injection of the MET + LFH loaded thermosensitive hydrogel in inhibiting CNV was evaluated on a mouse model of corneal alkali burn. Compared with the single administration of MET or LFH loaded thermosensitive hydrogel, the MET + LFH loaded thermosensitive hydrogel remarkably inhibited the formation of CNV. The sustained release of MET and an antibiotic (LFH) provides synergistic therapeutic outcome. As a result, the co-delivery of MET and LFH using PLGA-PEG-PLGA thermosensitive hydrogel by subconjunctival injection has great potential for ocular anti-angiogenic therapy.

The efficacy and safety of 0.5% Levofloxacin versus fortified Cefazolin and Amikacin ophthalmic solution for the treatment of suspected and culture-proven cases of infectious bacterial keratitis: a comparative study

Background: Bacterial keratitis is a major devastating ocular condition that quickly deteriorates the patient’s vision. Vigorous and prompt treatment of bacterial keratitis with broad-spectrum antibiotic eye-drops is preferred.

Objective: Evaluate the efficacy and safety of 0.5% Levofloxacin for the treatment of suspected and cultureproven cases of infectious bacterial keratitis in comparison to fortified Cefazolin and Amikacin ophthalmic solution.

Materials and methods: Seventy-one eyes from 69 patients suspected of having infectious bacterial keratitis were enrolled in the study. The patients were randomized into two arms, 0.5% Levofloxacin eye drops (34 eyes) or fortified Cefazolin and Amikacin (37 eyes). Sixty-eight eyes were included in the efficacy analysis. During treatment, on days 2, 7, 14, and 21, the patient’s symptoms and signs were scored from grade 0-3 (absent to severe).

Results: At the end of the treatment, 61 out of 71 eyes completely healed. The resolution of the keratitis was not significantly different between both groups. There were no significant differences in the mean time-duration for the ulcer to heal or for the symptoms and clinical signs to disappear between the two groups. No serious adverse events or side effects from the disease were found. The patients compliance was 80% based on the self-reported diaries.

Conclusion: The efficacy and safety of 0.5% topical Levofloxacin was comparable to fortified Cefazolin and Amikacin for the treatment of mild-to-moderate bacterial keratitis. Topical Levofloxacin is far superior because of its availability and patient compliance when used as monotherapy for the treatment of infectious bacterial keratitis.

Pharmacokinetics and aqueous humor penetration of levofloxacin 1.5% and moxifloxacin 0.5% in patients undergoing cataract surgery

Purpose

The objective of this study was to compare the pharmacokinetics of levofloxacin 1.5% and moxifloxacin hydrochloride 0.5% ophthalmic solutions in aqueous humor after multiple doses prior to cataract surgery.

Methods

Ninety-eight eyes underwent cataract surgery and met the requirements of PK analysis. Eligible eyes were randomly assigned in a 1:1 ratio to receive levofloxacin or moxifloxacin prior to cataract surgery and were randomized into one of four sampling time points (ie, 1, 2, 4, and 6 hour post-last dose). Randomization was investigator and laboratory-masked. Three days prior to cataract surgery, each patient instilled one drop of the assigned study medication into the operative eye four times daily. One aqueous humor specimen was collected from the eye at the randomized time point. Aqueous humor specimens were assayed for drug concentration using a validated liquid chromatography and tandem mass spectrometer.

Results

Concentrations of the drug in the aqueous humor, as described by mean C_max and pooled AUC_0–6 values, were greater for levofloxacin than moxifloxacin (C_max: 1.43, 0.87 μg/ml, respectively, P=0.008; AUC_0–6 6.1, 3.8 μg·min/ml, P<0.001 respectively). No treatment-emergent adverse events were reported.

Conclusion

Significantly greater drug exposures were attained in aqueous humor following the administration of levofloxacin 1.5% than moxifloxacin 0.5% ophthalmic solution. Achieving considerable higher drug concentration in the aqueous humor with levofloxacin 1.5% may demonstrate a greater potential for bacterial eradication.

Effects of awakening and the use of topical dexamethasone and levofloxacin on the cytokine levels in tears following corneal transplantation

Objectives. To study the short-term effect of eye opening and use of topical dexamethasone phosphate 0.1% and levofloxacin 0.5% on the cytokine levels in human tears. Methods. Prospective experimental design was used for tear collection from eyes of 10 healthy controls and 20 patients four days after penetrating keratoplasty (PKP) at awakening and after instilling dexamethasone or levofloxacin. The concentrations of different cytokines were measured by cytometric bead array. Results. At eye opening, IL-6 levels were higher in the PKP group as compared to the controls. Thirty minutes later, the released levels of IL-10, IL-13, IL-17, IFNγ, and CCL5 increased in controls, while CXCL8 decreased in both control and PKP groups. The release of the cytokines remained stable after 30 mins except for IFNγ, which showed a decrease in the controls following levofloxacin instillation. No short-term effects of the topically used dexamethasone and levofloxacin could be detected on the cytokine levels in controls and after PKP. Conclusions. Evidence of changes in the levels and time course of tear cytokines after awakening or eye opening could be established and the short-term confounding effects of dexamethasone and levofloxacin on the levels of released cytokines in human tears could be excluded.

Pharmacological treatment for infectious corneal ulcers

INTRODUCTION

Cornea ulceration and infectious keratitis are leading causes of corneal morbidity and blindness. Infectious causes are among the most frequent and most severe. Management strategies for bacterial corneal ulcers have changed significantly over the last decades, however with a more limited progress in the treatment and management of nonbacterial, infectious ulcers.

AREAS COVERED

This paper provides an overview of the current principles, strategies and treatment choices for infectious corneal ulcers in adults.

EXPERT OPINION

Topical application with a broad-spectrum antimicrobial remains the preferred method for the pharmacological management of infectious corneal ulcers. Increasing reports of clinical failures and in vitro resistance to antibiotics to treat the most common infectious (bacterial) corneal ulcers are increasing concerns. New approaches for improvement in the pharmacological management of corneal ulcers should focus on strategies for a more rational and evidence-based use of current antimicrobials and development of products to modulate the host immune response and to neutralize microbial toxins and other immune modulators.

Tear concentration and safety of levofloxacin ophthalmic solution 1.5% compared with ofloxacin ophthalmic solution 0.3% after topical administration in healthy adult volunteers

PURPOSE

This study evaluated the tear concentration and safety of levofloxacin ophthalmic solution 1.5%.

METHODS

Healthy adult volunteers (N = 125) received a single initial two-drop bilateral dose of either levofloxacin 1.5% (n = 100) or ofloxacin 0.3% (n = 25). Tear-fluid drug concentrations were measured at 15 minutes and at 2, 6, 12, and 24 hours after dosing. Subjects were dosed every 2 hours while awake and 4 and 6 hours after retiring (Days 1-3) and four times daily while awake (Days 4-14). Final measurements and evaluations were done on Day 15. Tear concentrations were determined by high-performance liquid chromatography. Safety and tolerability parameters included visual acuity, ophthalmoscopy, biomicroscopy, rose bengal staining, and adverse effects.

RESULTS

Tear concentrations after a single two-drop dose of levofloxacin 1.5% and ofloxacin 0.3% were above 2 microg/mL, a concentration that exceeds the minimum inhibitory concentration90 for levofloxacin in typical ocular bacterial pathogens at all time points through 24 hours. The area under the curve for the first 12 hours for levofloxacin 1.5% was 2703.5 +/- 574.22 microg.h/mL and 414.1 +/- 1179.00 microg.h/mL with ofloxacin 0.3%. Maximal concentrations were 806.9 +/- 8.57 and 73.3 +/- 165.46 microg/mL, respectively. Levofloxacin 1.5% and ofloxacin 0.3% did not differ in adverse event incidence, except for transient mild/moderate dysgeusia (14% of levofloxacin-treated subjects versus 4% of ofloxacin-treated subjects). No corneal epithelial damage or inflammatory changes were associated with levofloxacin.

CONCLUSION

A single dose of levofloxacin 1.5% produced tear fluid concentrations that were well above the minimum inhibitory concentration90 for typical ocular pathogens and was safe and well tolerated.

Ocular pharmacokinetics of besifloxacin following topical administration to rabbits, monkeys, and humans

PURPOSE

Studies were conducted to evaluate the ocular penetration and systemic exposure to besifloxacin, a fluoroquinolone antibiotic, following topical ocular administration to animals and humans.

METHODS

Besifloxacin ophthalmic suspension (0.6%) was administered as a topical ocular instillation to pigmented rabbits, cynomolgus monkeys, and human subjects. At predetermined intervals after dosing, samples of ocular tissues and plasma were collected and analyzed for besifloxacin levels using HPLC/MS/MS methods.

RESULTS

Besifloxacin demonstrated good ocular penetration in rabbits and monkeys, with rapid absorption and sustained concentrations observed in anterior ocular tissues through 24 h after a single administration. Maximum besifloxacin concentrations in conjunctiva, cornea, and aqueous humor of monkeys were 6.43 microg/g, 2.10 microg/g, and 0.796 microg/mL, respectively, after a single topical dose, and concentrations declined in these tissues with an apparent half-life of 5-14 h. Following a single topical ocular administration to humans, the maximum besifloxacin concentration in tears was 610 microg/g with concentrations decreasing to approximately 1.6 microg/g at 24 h. The resulting pharmacokinetic parameters for besifloxacin in human tears were evaluated relative to the MIC(90) values (microg/mL) for besifloxacin against Streptococcus pneumoniae (0.125), Staphylococcus aureus (0.25), Staphylococcus epidermidis (0.5), and Haemophilus influenzae (0.06). Following a single topical administration, the C(max)/MIC(90) ratios for besifloxacin in human tears were > or =1,220, and the AUC((0-24))/MIC(90) ratios were > or =2,500 for these relevant ocular pathogens. Following repeated 3-times daily (TID) topical ocular administration to human subjects with clinically diagnosed bacterial conjunctivitis, maximum besifloxacin concentrations in plasma were less than 0.5 ng/mL, on average.

CONCLUSIONS

Taken together, the results of the current investigation provide a PK/PD-based rationale that supports the use of besifloxacin for the safe and effective treatment of ocular infections.

Review of third-and fourth-generation fluoroquinolones in ophthalmology: in-vitro and in-vivo efficacy

INTRODUCTION

Beginning with second-generation ciprofloxacin 0.3% and ofloxacin 0.3%, fluoroquinolones have been widely used in the treatment and prophylaxis of ocular infections. However, their in-vitro potencies have been decreasing steadily since their introduction. Third-generation levofloxacin 0.5% produces higher ocular tissue penetration, thereby reducing the risk of selecting for decreased fluoroquinolone potency. Fourth-generation gatifloxacin 0.3% and moxifloxacin 0.5% have structural modifications that both reduce risk of resistance and improve potency against Gram-positive bacteria. A new third-generation formulation, levofloxacin 1.5%, was recently introduced, demonstrating increased ocular penetration compared with gatifloxacin 0.3% but clinical equivalence to its second-generation parent, ofloxacin 0.3%, in two randomized trials.

METHODS

We investigated the therapeutic potential of levofloxacin 1.5% and compared it to that of existing fourth-generation fluoroquinolones. A MEDLINE search was conducted using the following search terms: moxifloxacin or gatifloxacin; levofloxacin; minimum inhibitory concentration or prevention or prophylaxis; keratitis or endophthalmitis.

RESULTS

Nine eligible studies published between 2002 and 2008 were identified, eight of which are presented. The five in-vitro studies demonstrated that moxifloxacin and gatifloxacin are statistically more potent than levofloxacin against Gram-positive organisms and similar in potency in most cases of Gram-negative bacteria. In-vivo animal models testing moxifloxacin or gatifloxacin against levofloxacin 0.5% (no clinical trials testing the efficacy of levofloxacin 1.5% have yet been published) demonstrated that fourth-generation agents were superior to third-generation levofloxacin 0.5% for prophylaxis of Gram-positive bacteria-induced infections and were equal to, or better than, levofloxacin 0.5% for the treatment of Gram-negative infections.

CONCLUSION

Fourth-generation agents have increased potency against Gram-positive bacteria compared with levofloxacin, while maintaining similar potency against Gram-negative bacteria. Although levofloxacin 1.5% has demonstrated superior ocular penetration relative to gatifloxacin, the limited available data do not suggest this translates into superior clinical activity compared with moxifloxacin, which has significantly greater ocular penetration and better Gram-positive potency than gatifloxacin.