Nonclinical pharmacodynamics, pharmacokinetics, and safety of BOL-303224-A, a novel fluoroquinolone antimicrobial agent for topical ophthalmic use

Clinical Ocular Exposure Extrapolation for a Complex Ophthalmic Suspension Using Physiologically Based Pharmacokinetic Modeling and Simulation

The development of generic ophthalmic drug products with complex formulations is challenging due to the complexity of the ocular system and a lack of sensitive testing to evaluate the interplay of its physiology with ophthalmic drugs. New methods are needed to facilitate the development of ophthalmic generic drug products. Ocular physiologically based pharmacokinetic (O-PBPK) models can provide insight into drug partitioning in eye tissues that are usually not accessible and/or are challenging to sample in humans. This study aims to demonstrate the utility of an ocular PBPK model to predict human exposure following the administration of ophthalmic suspension. Besifloxacin (Bes) suspension is presented as a case study. The O-PBPK model for Bes ophthalmic suspension (Besivance® 0.6%) accounts for nasolacrimal drainage, suspended particle dissolution in the tears, ocular absorption, and distribution in the rabbit eye. A topical controlled release formulation was used to integrate the effect of Durasite® on Bes ocular retention. The model was subsequently used to predict Bes exposure after its topical administration in humans. Drug-specific parameters were used as validated for rabbits. The physiological parameters were adjusted to match human ocular physiology. Simulated human ocular pharmacokinetic profiles were compared with the observed ocular tissue concentration data to assess the OCAT models' ability to predict human ocular exposure. The O-PBPK model simulations adequately described the observed concentrations in the eye tissues following the topical administration of Bes suspension in rabbits. After adjustment of physiological parameters to represent the human eye, the extrapolation of clinical ocular exposure following a single ocular administration of Bes suspension was successful.

A Comprehensive Overview of the Antibiotics Approved in the Last Two Decades: Retrospects and Prospects

Due to the overuse of antibiotics, bacterial resistance has markedly increased to become a global problem and a major threat to human health. Fortunately, in recent years, various new antibiotics have been developed through both improvements to traditional antibiotics and the discovery of antibiotics with novel mechanisms with the aim of addressing the decrease in the efficacy of traditional antibiotics. This manuscript reviews the antibiotics that have been approved for marketing in the last 20 years with an emphasis on the antibacterial properties, mechanisms, structure-activity relationships (SARs), and clinical safety of these antibiotics. Furthermore, the current deficiencies, opportunities for improvement, and prospects of antibiotics are thoroughly discussed to provide new insights for the design and development of safer and more potent antibiotics.

Analysis of topical dosing and administration effects on ocular drug delivery in a human eyeball model using computational fluid dynamics

Predicting the spatial and temporal drug concentration distributions in the eyes is essential for quantitative analysis of the therapeutic effect and overdose issue via different topical administration strategies. To address such needs, an experimentally validated computational fluid dynamics (CFD) based virtual human eye model with physiologically realistic multiple ophthalmic compartments was developed to study the effect of administration frequency and interval on drug concentration distributions. Timolol was selected as the topical dosing drug for the numerical investigation of how administration strategy can influence drug transport and concentration distribution over time in the human eye. Administration frequencies employed in this study are 1-4 times per day, and the administration time intervals are Δt = 900 s, 1800 s, and 3600 s. Numerical results indicate that the administration frequency can significantly affect the temporal timolol concentration distributions in the ophthalmic compartments. More administrations per day can prolong the mediations at relatively high levels in all compartments. CFD simulation results also show that shorter administration intervals can help the medication maintain a relatively higher concentration during the initial hours. Longer administration intervals can provide a more stable medication concentration during the entire dosing time. Furthermore, numerical parametric analysis in this study indicates that the elimination rate in the aqueous humor plays a dominant role in affecting the drug concentrations in multiple ophthalmic compartments. However, it still needs additional clinical data to identify how much drugs can be transported into the cardiac and/or respiratory systems via blood circulation for side effect assessment.

Besifloxacin: A Critical Review of Its Characteristics, Properties, and Analytical Methods

Bacterial conjunctivitis has high impact on the health of the population, since it represents more than a third of ocular pathologies reported by health services worldwide. There is a high incidence of bacterial resistance to the antimicrobials most commonly used for the treatment of conjunctivitis. In this context, besifloxacin stands out, since it is a fluoroquinolone developed exclusively for topical ophthalmic use, presenting a low risk of developing resistance due to its reduced systemic exposure. Bausch & Lomb markets it as ophthalmic suspension, under the trade name Besivance™. Literature review on besifloxacin is presented, covering its pharmaceutical and clinical characteristics, and the analytical methods used to measure the drug in pharmaceutical products and biological samples. High performance liquid chromatography is the most used method for this purpose. A discussion on Green Chemistry is also presented, focusing the importance of the development of green analytical methods for the analysis of drugs.

Besifloxacin: Efficacy and Safety in Treatment and Prevention of Ocular Bacterial Infections

This comprehensive review summarizes the mechanism of action, pharmacokinetics, efficacy, and safety of besifloxacin ophthalmic suspension, 0.6% and examines its role in the treatment of ocular surface bacterial infections. Besifloxacin possesses balanced activity against bacterial topoisomerase II (also called DNA gyrase) and topoisomerase IV. It has shown a low potential to select for bacterial resistance in vitro and demonstrated strong in vitro activity against many Gram-positive, Gram-negative, and anaerobic organisms, including methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis (MRSA and MRSE, respectively). Ocular pharmacokinetic studies have shown that besifloxacin achieves high, sustained concentrations in the tear fluid and conjunctiva following topical administration, with negligible systemic exposure. Large randomized, controlled clinical trials have established the efficacy and safety of besifloxacin administered three times daily for 5 days for treatment of acute bacterial conjunctivitis in both adults and children, with high rates of clinical resolution (up to more than 70% by day 5) and bacterial eradication (more than 90% by day 5), and a low incidence of adverse events. Additionally, besifloxacin applied twice daily for 3 days demonstrated greater efficacy than vehicle in treating bacterial conjunctivitis. Case reports, a large retrospective chart review, and animal studies have provided supporting evidence for the efficacy of besifloxacin in the management of acute bacterial keratitis. There is some evidence to suggest that besifloxacin may provide an advantage over other current-generation fluoroquinolones in antimicrobial prophylaxis for ocular surgery. Besifloxacin is an appropriate option for treatment of bacterial conjunctivitis, and its use in the treatment of bacterial keratitis and lid disorders, as well as for surgical prophylaxis, appears promising and warrants further evaluation.

Besifloxacin in the management of bacterial infections of the ocular surface

Acute bacterial conjunctivitis is a common infection of the ocular surface. Increasing rates of bacterial resistance have prompted the development of new antibiotics with improved activity against the bacterial species most often found in this disease. Besifloxacin is the first topical chlorofluoroquinolone developed solely for ophthalmic use. Studies have attested to its in vitro potency against a broad range of bacteria, as well as its efficacy in clinical studies of bacterial conjunctivitis when dosed 2 or 3 times a day. This review provides an up-to-date summary of studies on causative pathogens in acute bacterial conjunctivitis; recent geographic trends in bacterial resistance among ocular pathogens, including that of methicillin-resistant Staphylococcus aureus; the efficacy of besifloxacin in preclinical and clinical studies; its safety; and the role of besifloxacin in combating resistant strains. Further, this review provides a brief update on bacterial keratitis, causative pathogens, the development of resistance among those pathogens, and the potential role of besifloxacin in the treatment of bacterial keratitis.

Rapid, sensitive and selective HPLC-MS/MS method for the quantification of topically applied besifloxacin in rabbit plasma and ocular tissues: Application to a pharmacokinetic study

Besifloxacin is a fourth-generation broad-spectrum fluoroquinolone registered for the topical treatment of bacterial conjunctivitis. In this study, a rapid, sensitive and selective liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for quantification of besifloxacin in rabbit plasma and ocular tissues using nateglinide as the internal standard (IS). The analyte and IS were separated on a Sepax GP-Phenyl column by isocratic elution with methanol-acetonitrile-5 mM ammonium formate-formic acid (29:55:16:0.1, v/v/v/v) as the mobile phase at a flow rate of 1.2 mL/min, and the total run time was 3.0 min. An electrospray ionization (ESI) source was applied and operated in the positive ion mode; multiple reaction monitoring (MRM) mode was used for quantification, and the monitored transitions were 394.2→377.1 for besifloxacin and m/z 318.3→166.1 for the IS. The calibration curve was linear over the range of 0.103-206 ng/mL for plasma and 2.06-2060 ng/mL for tears, aqueous humor, conjunctiva and cornea with correlation coefficient (r) greater than 0.99. The lower limit of quantification (LLOQ) for besifloxacin was 0.103 ng/mL for plasma and 2.06 ng/mL for other ocular tissues with good accuracy and precision. Intra- and inter-batch precision were both lower than 15% and accuracy ranged from 85% to 115% at all QC levels. The method was successfully applied to the pharmacokinetic study of besifloxacin in rabbit plasma and ocular tissues after single and multiple topical administrations.

Besifloxacin ophthalmic suspension 0.6% in the treatment of bacterial keratitis: a retrospective safety surveillance study

PURPOSE

The objective of this study was to collect and evaluate retrospective safety information about the use of besifloxacin ophthalmic suspension 0.6% for the treatment of bacterial keratitis.

METHODS

This was a retrospective, postmarketing surveillance study conducted at 10 clinical centers in the United States. The study population included 142 patients treated with besifloxacin ophthalmic suspension 0.6% for bacterial keratitis in one or both eyes. For perspective, data on 85 patients treated at these centers with moxifloxacin ophthalmic solution 0.5% for bacterial keratitis were also included. The analysis was designed to measure the types and rates of adverse events (AEs) reported during the treatment of bacterial keratitis with besifloxacin ophthalmic suspension 0.6%. Other treatment outcomes of interest included the development of corneal scarring and corneal neovascularization, measured or presumed bacterial eradication, ending visual acuity, and duration of pain before and after treatment.

RESULTS

There was one reported AE of mild superficial punctate keratitis in a patient using besifloxacin ophthalmic suspension 0.6%. The difference in AE frequencies between groups was not significant (P>0.999). Additional treatment outcomes were similar for both groups. Limitations of this report include the retrospective nature of the study.

CONCLUSIONS

These retrospective data suggest that besifloxacin ophthalmic suspension 0.6% was well tolerated when included in the treatment of bacterial keratitis; no serious AEs were reported. A prospective clinical trial is needed to better isolate the contribution of besifloxacin to the therapeutic outcome and to confirm these observations.

The safety of besifloxacin ophthalmic suspension 0.6 % used three times daily for 7 days in the treatment of bacterial conjunctivitis

BACKGROUND

Besifloxacin ophthalmic suspension 0.6 % (Besivance(®); Bausch & Lomb, Rochester, NY, USA) was approved by the FDA in 2009 for the treatment of bacterial conjunctivitis, with a recommended 7-day dosing regimen.

OBJECTIVE

The objective of this study was to compare the safety of besifloxacin ophthalmic suspension 0.6 %, administered three times a day for 7 days, with that of its vehicle.

METHODS

This randomized, multicenter, double-masked, vehicle-controlled, parallel-group study involved 518 patients ≥1 year of age with a clinical diagnosis of bacterial conjunctivitis. Patients were randomized 2:1 to treatment with besifloxacin 0.6 % ophthalmic suspension or vehicle, one drop in the infected eye(s) TID for 7 days. Main outcomes included the incidence and types of adverse events reported by the subject or observed by the investigator at each study visit.

RESULTS

Thirty-one ocular treatment-emergent adverse events (TEAEs) were reported by 28 subjects in the study eye; 19 occurred in 17/344 (4.9 %) besifloxacin patients, and 12 occurred in 11/170 (6.5 %) vehicle patients (p = 0.5362). Only two ocular events (mild instillation site reaction, one case in each group) were considered "definitely related" to study treatment. One event of self-limited dysgeusia in the besifloxacin group was considered definitely related to treatment; there were no other nonocular TEAEs considered related to treatment. There were no serious adverse events, and other safety outcomes (visual acuity, biomicroscopy, ophthalmoscopy) were unremarkable.

CONCLUSION

These findings indicate that besifloxacin ophthalmic suspension 0.6 % is safe in patients aged 1 year and older when used TID for 7 days.

The role of besifloxacin in the treatment of bacterial conjunctivitis

OBJECTIVE

To evaluate the role of besifloxacin in bacterial conjunctivitis treatment.

DATA SOURCES

Searches were made on MEDLINE/PubMed and EMBASE (January 2007 to January 2014) using the terms besifloxacin and Besivance. References from these publications were reviewed for additional resources. Additional information was collected from Bausch & Lomb, the manufacturer of Besivance; www.clinicaltrials.gov; and American Academy of Ophthalmology.

STUDY SELECTION AND DATA EXTRACTION

English-language documents were reviewed for pharmacology, pharmacokinetics, efficacy, and safety, with priority on clinical trials.

DATA SYNTHESIS

Three large randomized controlled clinical trials established the safety and efficacy of besifloxacin ophthalmic suspension 0.6% compared with placebo or active comparator (moxifloxacin ophthalmic solution 0.5%) given 3 times a day for 5 days for acute bacterial conjunctivitis (BC) treatment. Compared with placebo, besifloxacin had clinically superior bacterial eradication rates and was noninferior to moxifloxacin. Besifloxacin was compared with placebo in 2 randomized, placebo-controlled trials, dosed twice a day for 3 days. Superior efficacy was seen compared with placebo, which supports the shorter dosing schedule. Ophthalmic besifloxacin is well tolerated; the most common adverse effect (conjunctival redness) occurred in 2% of patients. Adverse effects in 1% to 2% of patients included blurred vision, eye pain, eye irritation, eye pruritus, and headache.

CONCLUSION

Besifloxacin 0.6% ophthalmic suspension 3 times a day for 5 days is safe and effective for BC. Twice-a-day dosing for 3 days was also effective-a simplified regimen compared with other fluoroquinolones. Disadvantages include price and lack of a generic. Further evaluation is needed to evaluate comparative efficacy among other ocular fluoroquinolones and unlabeled uses.

Besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days in the treatment of bacterial conjunctivitis in adults and children

BACKGROUND AND OBJECTIVE

Besifloxacin ophthalmic suspension 0.6% given thrice daily for 5 days is safe and effective in the treatment of patients with bacterial conjunctivitis. This study evaluated the safety and efficacy of besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days compared with vehicle in the treatment of bacterial conjunctivitis.

STUDY DESIGN

This was a multicenter, double-masked, randomized, vehicle-controlled, parallel-group study.

METHODS

A total of 474 patients aged ≥1 year with bacterial conjunctivitis were randomized in a 1 : 1 ratio to receive either besifloxacin ophthalmic suspension 0.6% or vehicle administered twice daily for 3 days. There were three study visits: day 1 (the baseline visit), day 4/5 (visit 2), and day 7 ± 1 (visit 3). The co-primary efficacy endpoints were bacterial eradication and clinical resolution at day 4/5 in designated study eyes of patients with culture-confirmed bacterial conjunctivitis. Secondary efficacy endpoints were bacterial eradication and clinical resolution at day 7 ± 1, individual clinical outcomes of ocular discharge and bulbar conjunctival injection at all visits; and microbial and clinical outcomes for overall bacterial species and individual Gram-positive and Gram-negative bacterial species at each follow-up visit. Safety endpoints included adverse events (AEs), changes in visual acuity and biomicroscopy findings at each visit, and changes in ophthalmoscopy findings at day 7 ± 1.

RESULTS

Bacterial eradication and clinical resolution rates were significantly higher in the besifloxacin group than in the vehicle group (115/135 [85.2%] vs 77/141 [54.6%], p < 0.001, and 89/135 [65.9%] vs 62/141 [44.0%], p < 0.001, respectively) at day 4/5. Rates of bacterial eradication continued to be significantly greater in the besifloxacin group (115/135 [85.2%] vs 91/141 [64.5%], respectively; p < 0.001) at day 7 ± 1; however, the rates of clinical resolution did not differ significantly between the groups (103/135 [76.3%] and 94/141 [66.7%], p = 0.209) at this visit. Ocular discharge and bulbar conjunctival injection at each visit were consistent with the primary outcomes. Clinical resolution and bacterial eradication with Gram-positive or Gram-negative organisms were consistent with the overall findings. All AEs in both groups were of mild or moderate severity and were considered unrelated to the treatment.

CONCLUSION

Treatment with besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days was effective and safe in adults and children with bacterial conjunctivitis.

CLINICAL TRIAL REGISTRATION

Registered at ClinicalTrials.gov as NCT00972777.

Besifloxacin ophthalmic suspension, 0.6%: a novel topical fluoroquinolone for bacterial conjunctivitis

Acute bacterial conjunctivitis, the most common cause of conjunctivitis, is responsible for approximately 1% of all primary-care consultations. Of the topical ophthalmic antibiotics used to treat acute bacterial conjunctivitis, fluoroquinolones are especially useful because they possess a broad antibacterial spectrum, are bactericidal in action, are generally well tolerated, and have been less prone to development of bacterial resistance. Besifloxacin, the latest advanced fluoroquinolone approved for treating bacterial conjunctivitis, is the first fluoroquinolone developed specifically for topical ophthalmic use. It has a C-8 chlorine substituent and is known as a chloro-fluoroquinolone. Besifloxacin possesses relatively balanced dual-targeting activity against bacterial topoisomerase IV and DNA gyrase (topoisomerse II), two essential enzymes involved in bacterial DNA replication, leading to increased potency and decreased likelihood of bacterial resistance developing to besifloxacin. Microbiological data suggest a relatively high potency and rapid bactericidal activity for besifloxacin against common ocular pathogens, including bacteria resistant to other fluoroquinolones, especially resistant staphylococcal species. Randomized, double-masked, controlled clinical studies demonstrated the clinical efficacy of besifloxacin ophthalmic suspension 0.6% administered three-times daily for 5 days to be superior to the vehicle alone and similar to moxifloxacin ophthalmic solution 0.5% for bacterial conjunctivitis. In addition, besifloxacin ophthalmic suspension 0.6% administered two-times daily for 3 days was clinically more effective than the vehicle alone for bacterial conjunctivitis. Besifloxacin has also been shown in preclinical animal studies to be potentially effective for the "off-label" treatment of infections following ocular surgery, prophylaxis of endophthalmitis, and the treatment of bacterial keratitis. Taken together, clinical and preclinical animal studies indicate that besifloxacin is an important new option for the treatment of ocular infections.

Challenges in assessing microbial susceptibility and predicting clinical response to newer-generation fluoroquinolones

PURPOSE

To determine the most appropriate methods for assessing the potential effectiveness of the newer topical fluoroquinolones gatifloxacin, moxifloxacin, and besifloxacin.

METHODS

This article is based on a literature search for published articles about the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of and measure of bacterial susceptibility to topical ophthalmic fluoroquinolones. Search terms included fluoroquinolones, susceptibility, resistance, minimal/minimum inhibitory concentration (MIC), PDs, PKs, and ocular, ophthalmic, or topical antibiotics.

RESULTS

Topical fluoroquinolones, particularly besifloxacin, gatifloxacin, and moxifloxacin, have become important treatment options for common ocular bacterial infections due to their broad-spectrum bactericidal activity and low toxicity. An important challenge in ophthalmology is identifying the most accurate in vivo and in vitro methods for evaluating the efficacy of these topical fluoroquinolones. The MIC is the most commonly used measure of in vitro susceptibility. In systemic therapy, this measure is combined with PK data of antibiotics to generate PD indices PK/PD whose breakpoints differentiate clinically susceptible from nonsusceptible bacterial pathogen populations. PD breakpoints are further tested in prospective studies for their ability to predict clinical efficacy. However, it is not known whether systemically derived breakpoints apply to the assessment of clinical susceptibility to ocular agents. Topical ocular antibiotics likely achieve higher concentrations at the target site than do systemically administered antibiotics, but these higher concentrations can be quickly reduced by reflex tearing and blinking induced by instillation. Hence, studies have been conducted in animals and humans to determine the PK concentrations of topically administered antibiotics in ocular compartments. When combined with MIC values for topical pathogens, the results have the potential to predict clinical efficacy after identification of the appropriate PK/PD target. Ocular studies incorporating PK/PD assessments have recently begun to be reported with newer fluoroquinolones, including besifloxacin, gatifloxacin, and moxifloxacin, whose prolonged contact time and potent bactericidal activity have translated into some of the most favorable PK/PD target values. However, the clinical relevance of these studies has yet to be determined.

CONCLUSION

There is still a clear need for predictive models to extend our understanding of the clinical susceptibility of ocular pathogens.

Integrated analysis of three bacterial conjunctivitis trials of besifloxacin ophthalmic suspension, 0.6%: microbiological eradication outcomes

Purpose

To assess clinical antimicrobial efficacy results obtained with besifloxacin ophthalmic suspension, 0.6%, administered three times a day (TID) for 5 days, integrated across three clinical trials of bacterial conjunctivitis and to investigate any microbiological eradication failures.

Methods

Clinical microbiological eradication data from three randomized, double-masked, parallel group studies of patients with bacterial conjunctivitis (two vehicle controlled; one active controlled with moxifloxacin ophthalmic solution, 0.5%) were integrated. All bacterial samples isolated at baseline above the species-specific threshold value were subjected to antimicrobial susceptibility testing. Samples isolated at subsequent visits were subjected to susceptibility testing and pulsed-field gel electrophoresis (PFGE) to investigate the cause of eradication failures and the potential for drug resistance development.

Results

Visit 2 (day 4 or 5) and visit 3 (day 8) overall microbiological eradication rates were 92.2% and 88.4% for besifloxacin ophthalmic suspension compared with 61.4% and 72.5% for vehicle and 91.6% and 85.7% for moxifloxacin ophthalmic solution. Visit 2 and visit 3 microbiological eradication rates for Gram-positive and Gram-negative isolates and for individual species were consistent with the overall eradication rates. The majority of observed eradication failures in any treatment group were due to the persistence of the pathogen isolated at baseline. Eradication failures in the besifloxacin treatment group were not associated with lower antimicrobial susceptibility at baseline. PFGE data showed that the majority of bacterial strains in eyes with eradication failures were identical to the strain isolated at baseline; these eradication failures were not associated with a lower antimicrobial susceptibility at the follow-up visit.

Conclusion

Treatment with besifloxacin ophthalmic suspension, 0.6%, administered TID for 5 days resulted in microbiological eradication rates that were ≥ 90% across the three clinical studies for the common pathogens of bacterial conjunctivitis. The few eradication failures were not due to fluoroquinolone resistance at baseline and/or resistance development during treatment.

Acute and twenty-eight days repeated oral dose toxicity study of besifloxacin in Wistar albino rats

The purpose of this study was to investigate the potential acute and 28-day repeated oral toxicities of besifloxacin (BAF) in Wistar albino rats. In oral acute and repeated dose study, BAF was administered to both sex of rats, at dose levels of 0, 300, 600, 900 mg/kg/day and 0, 100, 200, 500 mg/kg/day, respectively. In the acute study, total white blood cell (WBC) (male, 43.74%; female, 42.60%) and total bilirubin (T-BIL) (male, 80%; female, 60%) were significantly increase, total protein (TP) (male, 23.24%; 27.80%) was significantly decreased, and significant incidence of pericholangitis (male, 83.33%; female, 75%) was shown in males and females of high-dose groups. In repeated oral dose toxicity study, similar type effects were also observed after serum hematological and serum biochemical analysis, whereas additionally sever hepatic injury and focal ulceration in gastric mucosa also observed in high dose groups of both sexes after histopathological analysis. However these toxic effects of besifloxacin were transient and reversible and no-observed adverse effect level (NOAEL) were 300 mg/kg/day for acute and 100 mg/kg/day for repeated dose toxicity study, respectively.

Efficacy and tolerability of besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days in the treatment of bacterial conjunctivitis: a multicenter, randomized, double-masked, vehicle-controlled, parallel-group study in adults and children

BACKGROUND

Besifloxacin is a topical fluoroquinolone with potent in vitro activity against a broad spectrum of ocular pathogens, including drug-resistant strains. Besifloxacin ophthalmic suspension 0.6% given 3 times daily for 5 days has been reported to be more effective than its vehicle in the treatment of bacterial conjunctivitis. Pharmacokinetic/pharmacodynamic modeling suggests that besifloxacin might also be effective given twice daily.

OBJECTIVE

This study evaluated the efficacy and tolerability of besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days compared with vehicle (formulation without besifloxacin) in the treatment of adults and children with bacterial conjunctivitis.

METHODS

This was a multicenter, prospective, randomized, double-masked, vehicle-controlled, parallel-group study. Patients aged ≥1 year with bacterial conjunctivitis were randomized to receive besifloxacin ophthalmic suspension or vehicle administered twice daily for 3 days. There were 3 study visits: the baseline visit, visit 2 (day 4 or 5), and visit 3 (day 7±1). Participants recorded the times of medication instillation in a patient diary. The primary end points were clinical resolution and bacterial eradication of the baseline bacterial infection at visit 2 in patients with culture-confirmed bacterial conjunctivitis. Secondary end points were clinical resolution and bacterial eradication of the baseline bacterial infection at visit 3, individual clinical outcomes (ocular conjunctival discharge and bulbar conjunctival injection) at the follow-up visits, and microbial and clinical outcomes for overall bacterial species and individual gram-positive and gram-negative bacterial species. Tolerability assessments included ocular adverse events (AEs), changes in visual acuity, biomicroscopy and ophthalmoscopy findings, and nonocular AEs.

RESULTS

Of 202 patients randomized to treatment (mean [SD] age, 25.2 [24.3] years; 56.9% female; 76.7% white), 109 had culture-confirmed bacterial conjunctivitis (53 besifloxacin ophthalmic suspension, 56 vehicle). At visit 2, the besifloxacin ophthalmic suspension group had significantly greater rates of clinical resolution compared with the vehicle group (37/53 [69.8%] vs 21/56 [37.5%], respectively; P < 0.001), as well as significantly greater rates of bacterial eradication (46/53 [86.8%] vs 32/56 [57.1%]; P < 0.001). At visit 3, rates of bacterial eradication were also significantly greater in the besifloxacin ophthalmic suspension group compared with the vehicle group (46/53 [86.8%] vs 39/56 [69.6%]; P = 0.038). Results for the individual clinical outcomes and microbial and clinical outcomes by gram-positive and gram-negative species were consistent with the primary efficacy outcomes. The incidence of ocular AEs did not differ significantly between treatment groups (4/94 [4.3%] vs 8/98 [8.2%]). Ocular AEs in all treated eyes in the respective groups included bacterial conjunctivitis (3/157 [1.9%] and 5/154 [3.2%]), conjunctivitis (3/157 [1.9%] and 4/154 [2.6%]), and allergic conjunctivitis (2/157 [1.3%] and 1/154 [0.6%]). These events were of mild or moderate severity. Changes in visual acuity and biomicroscopy and ophthalmoscopy findings were comparable between groups. There were few nonocular AEs (2/94 [2.1%] vs 3/98 [3.1%]; P = NS), none of them considered treatment related.

CONCLUSION

In these adults and children with bacterial conjunctivitis, treatment with besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days was effective and well tolerated. ClinicalTrials.gov identifier: NCT00972777.

Ocular pharmacokinetics/pharmacodynamics of besifloxacin, moxifloxacin, and gatifloxacin following topical administration to pigmented rabbits

PURPOSE

The purpose of this investigation was to evaluate the ocular pharmacokinetic/pharmacodynamic (PK/PD) relationship for besifloxacin, moxifloxacin, and gatifloxacin using rabbit ocular PK data, along with in vitro minimum inhibitory concentration (MIC90) values against methicillin- and ciprofloxacin-resistant Staphylococcus aureus (MRSA-CR) and Staphylococcus epidermidis (MRSE-CR).

METHODS

Rabbits received a topical instillation of Besivance™ (besifloxacin ophthalmic suspension, 0.6%), Vigamox (moxifloxacin hydrochloride ophthalmic solution, 0.5% as base), or Zymar (gatifloxacin ophthalmic solution, 0.3%), and ocular tissues and plasma were collected from 4 animals/treatment/collection time at 8 predetermined time intervals during the 24h after dosing. Ocular levels of each agent were measured by LC/MS/MS, and PK parameters (Cmax, Tmax, and AUC₀₋₂₄) were determined. AUC₀₋₂₄/MIC₉₀ ratios were calculated for tears, conjunctiva, cornea, and aqueous humor using previously reported MIC₉₀values for MRSA-CR and MRSE-CR.

RESULTS

All of the fluoroquinolones tested demonstrated rapid penetration into ocular tissues after a single instillation. Besifloxacin demonstrated the highest exposure in tear fluid, while exposure in conjunctiva was comparable for all 3 compounds. Peak concentrations of all fluoroquinolones in aqueous humor were at or below ~1g/mL. In comparison with their MIC₉₀values against MRSE-CR and MRSA-CR, besifloxacin achieved an AUC₀₋₂₄/MIC₉₀ ratio of ~800 in tears, compared with values of ≤10 for moxifloxacin and gatifloxacin. In cornea, conjunctiva, and aqueous humor, the AUC₀₋₂₄/MIC₉₀ ratios were <10 for all compounds. However, in these tissues AUC₀₋₂₄/MIC₉₀ ratios for besifloxacin were 1.5- to 38-fold higher than moxifloxacin and gatifloxacin.

CONCLUSIONS

In rabbits, besifloxacin demonstrates a nonclinical ocular PK profile characterized by high and sustained concentrations in tear fluid, resulting in AUC₀₋₂₄/MIC₉₀ ratios of ~800 for ciprofloxacin-resistant MRSE and MRSA after a single administration. Although besifloxacin had the highest AUC₀₋₂₄/MIC₉₀ratios for intraocular tissues, the ratios for all of the drugs were below the target values needed for effective bacterial killing of ciprofloxacin-resistant MRSE and MRSA. Taken together, these nonclinical data indicate that besifloxacin has a favorable ocular PK/PD profile, consistent with the reported clinical efficacy of besifloxacin in the treatment of bacterial conjunctivitis, and consistent with the profile needed for ocular surface sterilization.

Besifloxacin ophthalmic suspension: emerging evidence of its therapeutic value in bacterial conjunctivitis

Objective

To outline the pharmacodynamics, efficacy and safety of besifloxacin ophthalmic suspension 0.6% in the treatment of bacterial conjunctivitis.

Quality of Evidence

MEDLINE database was searched to review recent pharmacodynamic and clinical studies evaluating besifloxacin and comparing besifloxacin to other topical antibiotics for ophthalmic use. Findings were limited to full-text articles from clinical journals in the English language.

Main Message

Bacterial resistance is a common source for treatment failure in bacterial conjunctivis. Besifloxacin, a novel fourth generation synthetic fluoroquinolone is likely to show lower resistance rates due to its mechanism of action and its short-term use for ocular infections only (decreased systemic exposure). Besifloxacin displays improved pharmacodynamic properties compared to other commonly used fluoroquinolones and has shown to be efficacious and safe in clinical studies.

Conclusion

Besifloxacin ophthalmic suspension 0.6% provides safe and efficacious treatment for bacterial conjunctivitis. The factors leading to bacterial resistance are diminished, which allows besifloxacin to be a favorable treatment option.

Bactericidal activity of besifloxacin against staphylococci, Streptococcus pneumoniae and Haemophilus influenzae

OBJECTIVES

Besifloxacin is a novel fluoroquinolone that was recently approved for topical treatment of bacterial conjunctivitis. The compound was shown to be active in vitro against a broad spectrum of bacteria, including isolates resistant to other antibacterials. Here, the bactericidal activity of besifloxacin was evaluated against the most common bacterial conjunctivitis pathogens.

METHODS

MIC, MBC and time-kill experiments with besifloxacin and comparators were performed according to CLSI guidelines. Quinolone resistance-determining regions (QRDRs) were sequenced using standard PCR-based techniques.

RESULTS

MIC and MBC data indicated that besifloxacin was the most potent fluoroquinolone tested against Staphylococcus aureus (n = 30), Staphylococcus epidermidis (n = 15) and Streptococcus pneumoniae (n = 35), while all fluoroquinolones were highly active against Haemophilus influenzae (n = 40). Besifloxacin MBC:MIC ratios were < or = 4 for 97.5% of all isolates tested (n = 120). All fluoroquinolones tested, as well as tobramycin, were bactericidal, while azithromycin was bactericidal against S. pneumoniae and H. influenzae, but bacteriostatic against the staphylococci. Time-kill assays with all four species showed that besifloxacin caused > or = 1000-fold killing within 2 h for 11 of 12 isolates. Only one isolate treated with moxifloxacin and three ciprofloxacin-treated isolates achieved the same level of bactericidal activity under the same conditions. Unlike the comparator fluoroquinolones, besifloxacin maintained a high potency and bactericidal activity even against strains that contained multiple mutations in the genes encoding DNA gyrase and topoisomerase IV.

CONCLUSIONS

Overall, besifloxacin demonstrated rapid bactericidal activity against the four major human pathogens tested here, including isolates that showed in vitro resistance to other fluoroquinolones, beta-lactams, macrolides or aminoglycosides.

Besifloxacin: a novel anti-infective for the treatment of bacterial conjunctivitis

Bacterial conjunctivitis, commonly known as pink eye, is demographically unbiased in its prevalence and can be caused by a variety of aerobic and anaerobic bacteria. Timely empiric treatment with a broad-spectrum anti-infective, such as a topical fluoroquinolone, is critical in preventing potentially irreversible ocular damage. However, the rise in ocular methicillin- resistant Staphylococcus aureus isolates and the patterns of fluoroquinolone resistance for patients with other ocular bacterial infections mandate the need for new agents targeted for ocular use. Besifloxacin, a novel broad-spectrum fluoroquinolone, is approved for the treatment of bacterial conjunctivitis. It has a uniquely balanced dual-targeting activity that inhibits both DNA gyrase and topoisomerase IV and is associated with a lower incidence of resistance development. Besifloxacin is not marketed in other formulations, ensuring that its exposure is limited to bacterial populations in and around the eye. This specifically precludes any bacterial exposure to besifloxacin resulting from systemic use, which further reduces the likelihood of emergence of bacterial resistance. In vitro, besifloxacin has demonstrated equivalent or superior activity compared with other commonly used topical antibiotics. In clinical trials, besifloxacin has consistently demonstrated efficacy and safety in the treatment of patients with bacterial conjunctivitis. Besifloxacin is considered safe and is well tolerated with no observed contraindications.

Efficacy and safety of besifloxacin ophthalmic suspension 0.6% in children and adolescents with bacterial conjunctivitis: a post hoc, subgroup analysis of three randomized, double-masked, parallel-group, multicenter clinical trials

BACKGROUND

Acute conjunctivitis is the most frequent eye disorder seen by primary care physicians and one that often affects children. Besifloxacin is a new topical fluoroquinolone, the first chlorofluoroquinolone, for the treatment of bacterial conjunctivitis.

OBJECTIVE

To examine the efficacy and safety of besifloxacin ophthalmic suspension 0.6% in patients aged 1-17 years with bacterial conjunctivitis.

METHODS

This was a post hoc analysis of a subgroup of pediatric patients aged 1-17 years who had participated in three previously reported, randomized, double-masked, parallel-group, multicenter, clinical trials evaluating the safety and efficacy of besifloxacin in the treatment of bacterial conjunctivitis. The studies were conducted in a community setting (clinical centers). All three clinical trials included children (aged > or = 1 year) with a clinical diagnosis of bacterial conjunctivitis in at least one eye, based on the presence at baseline of grade 1 or greater purulent conjunctival discharge and conjunctival injection, and pin-hole visual acuity of at least 20/200 in both eyes for verbal patients. Two trials were vehicle controlled; the third trial was comparator controlled (moxifloxacin hydrochloride ophthalmic solution 0.5% as base). In all studies, besifloxacin ophthalmic suspension 0.6% was administered as one drop in the affected eye(s) three times daily, at approximately 6-hourly intervals, for 5 days. The main outcome measures were clinical resolution and microbial eradication at visit 2 (day 4 +/- 1 in one study; day 5 +/- 1 in the other two studies) and visit 3 (day 8 or 9). Data from the two vehicle-controlled studies were combined for the assessments to provide greater statistical power.

RESULTS

This analysis included 815 pediatric patients aged 1-17 years (447 with culture-confirmed bacterial conjunctivitis). Clinical resolution was significantly greater (p < 0.05) in the besifloxacin group than in the vehicle group at both visit 2 (53.7% vs 41.3%) and visit 3 (88.1% vs 73.0%). Similarly, microbial eradication was significantly higher with besifloxacin than with vehicle at visit 2 (85.8% vs 56.3%) and visit 3 (82.8% vs 68.3%). No significant differences in clinical resolution and microbial eradication were noted between besifloxacin and moxifloxacin. Besifloxacin was well tolerated, with similar incidences of adverse events in the besifloxacin, vehicle, and moxifloxacin groups.

CONCLUSION

Besifloxacin ophthalmic suspension 0.6% was shown to be safe and effective for the treatment of bacterial conjunctivitis in children and adolescents aged 1-17 years.

Efficacy of besifloxacin in a rabbit model of methicillin-resistant Staphylococcus aureus keratitis

PURPOSE

The purpose of this study was to determine the effectiveness of topically applied besifloxacin (0.6%), gatifloxacin (0.3%), and moxifloxacin (0.5%) for the late treatment of experimental methicillin-resistant Staphylococcus aureus (MRSA) keratitis.

METHODS

One hundred colony-forming units (CFUs) of bacteria were injected intrastromally into rabbit corneas. Sixteen hours after infection, one topical drop of phosphate-buffered saline, besifloxacin, gatifloxacin, or moxifloxacin was applied to each eye every 15 minutes for 5 doses and then every 30 minutes for 14 doses. Eyes were examined before and after treatment by slit lamp biomicroscopy. Corneas were harvested from treated and untreated rabbits for the quantitation of bacteria. Minimal inhibitory concentrations (MICs) were determined in vitro for each fluoroquinolone.

RESULTS

None of the treatments had an effect on clinical severity (P > 0.05). Although there were no differences in clinical severity between any groups after treatment, the mean log10 CFU of MRSA recovered from besifloxacin-treated corneas (5.111 +/- 0.251) was significantly lower than the CFU recovered from corneas treated with phosphate-buffered saline (7.006 +/- 0.144), gatifloxacin (7.108 +/- 0.346), and moxifloxacin (7.473 +/- 0.144; P < 0.001). CFU recovered from gatifloxacin- and moxifloxacin-treated corneas were not significantly different from phosphate-buffered saline-treated corneas (P = 1.000). The MICs against the MRSA strain were 8 microg/mL for both gatifloxacin and moxifloxacin, whereas the MIC for besifloxacin was 1 microg/mL.

CONCLUSION

Besifloxacin had an 8-fold lower MIC for MRSA than gatifloxacin and moxifloxacin and was significantly more effective than gatifloxacin and moxifloxacin in reducing the number of MRSA in the rabbit cornea 16 hours after infection.

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.

Impact of antibiotic resistance in the management of ocular infections: the role of current and future antibiotics

Purpose:

This article reviews the effects of the increase in bacterial resistance on the treatment of ocular infections.

Design:

Interpretive assessment.

Methods:

Literature review and interpretation.

Results:

Ocular bacterial infections include conjunctivitis, keratitis, endophthalmitis, blepharitis, orbital cellulitis, and dacryocystitis. Treatment for most ocular bacterial infections is primarily empiric with broad-spectrum antibiotics, which are effective against the most common bacteria associated with these ocular infections. However, the widespread use of broad-spectrum systemic antibiotics has resulted in a global increase in resistance among both Gram-positive and Gram-negative bacteria to a number of the older antibiotics as well as some of the newer fluoroquinolones used to treat ophthalmic infections. Strategies for the prevention of the increase in ocular pathogen resistance should be developed and implemented. In addition, new antimicrobial agents with optimized pharmacokinetic and pharmacodynamic properties that have low toxicity, high efficacy, and reduced potential for the development of resistance are needed.

Conclusions:

New antimicrobial agents that treat ocular infections effectively and have a low potential for the development of resistance could be a part of strategies to prevent the global increase in ocular pathogen resistance.

Phase III efficacy and safety study of besifloxacin ophthalmic suspension 0.6% in the treatment of bacterial conjunctivitis

OBJECTIVE

To compare the clinical and antimicrobial efficacy of besifloxacin ophthalmic suspension 0.6% with that of vehicle in the treatment of bacterial conjunctivitis.

RESEARCH DESIGN AND METHODS

This was a randomized, multicenter, double-masked, vehicle-controlled study. A total of 957 patients aged 1 year and older with bacterial conjunctivitis were randomized to treatment with besifloxacin ophthalmic suspension 0.6% or vehicle applied topically three times daily for 5 days.

MAIN OUTCOME MEASURES

Primary endpoints were clinical resolution and microbial eradication of baseline bacterial infection at Visit 2 (Day 5 +/- 1). Secondary endpoints included clinical resolution and microbial eradication at Visit 3 (Day 8 or 9), individual clinical outcomes at follow-up visits, and safety.

CLINICAL TRIAL REGISTRATION

NCT number, NCT00347932.

RESULTS

Three hundred and ninety patients had culture-confirmed bacterial conjunctivitis. Clinical resolution and microbial eradication were significantly greater with besifloxacin ophthalmic suspension than with vehicle at Visit 2 (45.2% vs. 33.0%, p = 0.0084; and 91.5% vs. 59.7%, p < 0.0001, respectively) and Visit 3 (84.4% vs. 69.1%, p = 0.0011; and 88.4% vs. 71.7%, p < 0.0001, respectively). Results for secondary endpoints of individual clinical outcomes were consistent with primary endpoints. Fewer eyes receiving besifloxacin ophthalmic suspension experienced adverse events than those receiving vehicle (9.2% vs. 13.9%; p = 0.0047).

CONCLUSIONS

Besifloxacin ophthalmic suspension produces clinical resolution and microbial eradication rates significantly better than vehicle and is safe for the treatment of bacterial conjunctivitis.

LIMITATIONS

A limitation of this study is the lack of a non-treatment control group.