Ocular surface distribution and pharmacokinetics of a novel ophthalmic 1% azithromycin formulation

Long-Term Prognosis of Anterior Blepharitis After Topical Antibiotics Treatment

OBJECTIVE

We conducted a retrospective evaluation of the long-term prognosis associated with anterior blepharitis subsequent to topical antibiotic intervention.

METHODS

Inclusion criteria encompassed 92 eyes of 92 patients who exhibited clinical manifestations of anterior blepharitis and undergone a regimen of topical azithromycin. The follow-up duration extended to a minimum of one year within our medical facility. The diagnostic framework for anterior blepharitis, along with the evaluation of both objective and subjective manifestations, adhered to the Blepharitis Preferred Practice Pattern as promulgated by the American Academy of Ophthalmology. Relapse denoted the resurgence of blepharitis symptoms subsequent to the primary treatment, necessitating the instigation of either topical or oral therapeutic measures.

RESULTS

Of 92 cases of anterior blepharitis, 48 showed recurrence, with a recurrence rate of 52.2%. During the follow-up period, 2 patients experienced 5 relapses, 2 patients experienced 4 relapses, 5 patients experienced 3 relapses, 13 patients experienced 2 relapses, and 26 patients experienced 1 relapse. When the patients were divided into three groups: multiple recurrence group (22 patients), single recurrence group (26 patients), and no recurrence group (44 patients), there were no significant differences in the blepharitis finding score before and after the initial treatment among three groups. However, significantly fewer patients in the no recurrence group required further treatment after initial treatment, and the percentage of patients with residual blepharitis during follow-up was significantly lower in the no recurrence group.

CONCLUSIONS

Our data suggest that patients with residual findings after blepharitis treatment are at a risk of recurrence.

Efficacy and safety of topical azithromycin therapy in patients with blepharitis and meibomian gland dysfunction

PURPOSE

To assess the effects of 1% azithromycin ophthalmic solution (AZM) in patients with bacterial blepharitis accompanied by meibomian gland dysfunction (MGD).

STUDY DESIGN

A multicenter, single arm, prospective interventional study.

METHODS

AZM was administered to the affected eyes twice daily for the first 2 days and once daily for the subsequent 12 days. Lid margin hyperaemia/redness, collarette at the root of the eyelashes, conjunctival hyperaemia, foreign body sensation, and epiphora were assessed on Days 1, 14, and 28. The Dry Eye-related Quality of Life Score (DEQS) and objectives related to MGD, including lid vascularity, lid margin irregularity, foaming, lid plugging, keratoconjunctival disorders, Marx line, meibum grade, and tear breakup time, were also assessed. Bacterial culture of the conjunctival sac and meibum was performed on Days 1 and 14.

RESULTS

Twenty-four eyes of 24 patients (10 men/14 women, mean age 72.3 ± 13.2) were included. On Days 14 and 28, the total score, lid vascularity, lid plugging, and meibum grade showed significant improvement (p < 0.05). On Day 1, 71 strains were isolated from 22 of the 24 eyes (91.7%). Cutibacterium acnes, Corynebacterium spp., and Staphylococci were detected at high frequencies. The overall disappearance rates of the bacteria in the conjunctival sac and meibum at the end of treatment were 65.7% and 58.3%, respectively. No serious ocular or systemic adverse events were observed.

CONCLUSION

Fourteen-day treatment with AZM was effective in patients with blepharitis accompanied by MGD, and the efficacy of AZM persisted for a period after the treatment.

Efficacy of azithromycin hydrate ophthalmic solution for treatment of internal hordeolum and meibomitis with or without phlyctenular keratitis

PURPOSE

To evaluate the efficacy of azithromycin hydrate ophthalmic solution for the treatment of internal hordeolum and meibomitis with or without phlyctenular keratitis.

STUDY DESIGN

Retrospective study.

METHODS

Patients diagnosed with internal hordeolum or meibomitis were prescribed azithromycin hydrate ophthalmic solution twice daily for 2 days and then once daily for 12 days. Depending on the presence of meibomitis-related keratoconjunctivitis (MRKC), we further divided the patients with meibomitis into three subgroups: meibomitis alone (non-MRKC group), meibomitis with non-phlyctenular MRKC (non-phlyctenular group), and meibomitis with phlyctenular MRKC (phlyctenular group). Inflammatory findings (eyelid redness and conjunctival hyperemia) were scored before and after treatment. Some patients also underwent culture testing fluids discharged by the meibomian gland orifices.

RESULTS

Three patients (3 eyes) had internal hordeolum and 16 patients (16 eyes) had meibomitis. After treatment, the inflammatory findings disappeared in all eyes with internal hordeolum. Among the patients with meibomitis, three eyes were in the non-MRKC, six in the non-phlyctenular, and seven in the phlyctenular group. The inflammatory findings were significantly improved only in the phlyctenular group. Among seven eyes with positive culture results, Cutibacterium acnes was detected in five, and treatment improved the inflammatory findings in all of these eyes.

CONCLUSION

Azithromycin hydrate ophthalmic solution is effective for the treatment of inflammatory meibomian gland diseases, including internal hordeolum and meibomitis. In particular, the agent is highly efficient in patients with phlyctenular MRKC.

Corneal foreign bodies: are antiseptics and antibiotics equally effective?

PURPOSE

To compare the effect of antiseptics and antibiotics on the occurrence of Infectious Keratitis (IK) secondary to Corneal Foreign Body (CFB) removal.

METHODS

Multicenter retrospective study conducted between June 2020 and June 2022 in patients referred for CFBs and treated with Picloxydine (Group 1) or Tobramycin (Group 2) for 7 days. A follow-up visit was scheduled on Day 3 (D3) and a phone call on D30. The primary outcome measure was the occurrence of IK.

RESULTS

307 patients (300 men) with a mean age of 42.8 (14.8) years were included. The mean (SD) time to consultation was 43.1 (45.6) hours. Picloxydine and Tobramycin were given to 155 and 152 patients. Half of patients (n = 154, 50.2%) were building workers and 209 (68.1%) did not wear eye protections. CFBs were mainly metallic (n = 292, 95.1%). Upon referral, rust was found in 220 patients (72.1%). A burr was used in 119 (38.9%) patients. IK occurred in 15 (4.9%) patients, 8 (5.3%) in Group 1 and 7 (4.5%) in Group 2 (p = 0.797). IK was successfully treated in all cases. Persistent rust was found in 113 patients (36.9%) on D3 without difference between burr or needle use (p = 0.278). On D3, corneal healing was delayed in 154 patients (47.2%), mainly in burr-treated patients (p = 0.003). The mean (SD) work stoppage duration was 0.32 (0.98) days.

CONCLUSION

IK rate was 4.9%. The efficacy of antibiotics and antiseptics was similar on CFB removal. Using a burr was associated with a longer healing time. CFBs had a limited social impact.

Efficacy of Topical Azithromycin versus Systemic Doxycycline in Treatment of Meibomian Gland Dysfunction

Background

Ocular surface disease (OSD) is a multifactorial and highly frequent problem. Inadequate or unstable tear film is the main cause, which leads to visual impairments. One of the primary causes of OSD is meibomian gland dysfunction (MGD), with a prevalence of 3.5 to 70%. The aim of this work was to compare the efficacy of azithromycin topical eye drops versus oral doxycycline in MGD individuals.

Methods

This prospective comparative cohort research was carried out on 56 patients of both sexes of any age with symptomatic MGD. Randomly, patients were classified into two equal groups: Group 1 was treated twice daily for 4 weeks with topical azithromycin 1% eye drops, while group 2 received oral doxycycline 100 mg capsules twice daily for 4 weeks.

Results

In the 1st follow-up, there was a significant difference between the studied groups in pain and discomfort degree (P value = 0.024) as group 1 showed a higher number of patients with a mild pain degree (P value = 0.013) while group 2 showed a higher number of patients with a severe pain degree (P value = 0.022). There was an insignificant difference between the studied groups in moderate pain degree and lid margin telangiectasia. Conjunctivitis, frothy discharge, and meniscus floaters were significantly higher in group 2 than in group 1 (P value = 0.013, 0.028, and 0.031, respectively). In group 1, the break-up time test was significantly higher than in group 2 (P value = 0.023). In the 2nd follow up, in group 2 only meniscus floaters were significantly higher than in group 1 (P value = 0.044), while in group 1 break-up time test was significantly higher than in group 2 (P value = 0.029). Otherwise, there is no significant difference between both the groups.

Conclusions

Meibomian gland dysfunction (MGD) could be treated effectively with oral doxycycline and topical azithromycin by improving symptoms, clinical signs, and stabilization of tear film. Moreover, the topical azithromycin group seemed to be superior over the oral doxycycline group in improving the quality of tear film in the short term, having fewer side effects, more compliance, and better tolerability.

A Bioequivalence Study With Pharmacokinetic Endpoints for Azithromycin Eye Drops

Azithromycin eye drops with a bioadhesive ocular drug-delivery system can offer a simplified dosing regimen. In this study, we compared the pharmacokinetic properties and assessed the bioequivalence of a newly developed generic azithromycin eye drop with a branded formulation. This open-label, single-dose, randomized, crossover, sparse-sampling ocular bioequivalence study was conducted on 48 healthy Chinese volunteers. Tear samples were collected for up to 36 hours, and each participant was randomly allocated to one of the prespecified sampling times. Tear drug concentrations were determined using a validated liquid chromatography-tandem mass spectrometry method. The pharmacokinetic parameters were calculated via noncompartmental analysis. A nonparametric bootstrap method was used to obtain 90% confidence intervals (CIs) for the ratios of the test and reference drugs. Tolerability was evaluated for adverse events (AEs). After bootstrapping (1000 iterations), the 90%CIs for the log-transformed ratios of Cmax , AUC0-t , and AUC0-∞ were within the acceptable bioequivalence range (80%-125%). No moderate-to-severe AEs were reported for either formulation. Bioequivalence was demonstrated between the two formulations. The sparse-sampling design with the bootstrapping technique is promising for bioequivalence studies of topical ophthalmic drugs.

Analysis of treatment protocols using azithromycin eye drops for bacterial blepharitis: second report-bacteriological investigation

PURPOSE

To gain new insights into the etiology of blepharitis, we investigated the causative bacteria in patients with blepharitis and the effects of 1% azithromycin ophthalmic solution.

STUDY DESIGN

A multicenter, prospective observational study.

METHODS

After the subjects were diagnosed as having blepharitis they were administered 1% azithromycin ophthalmic solution for up to 14 days. Bacterial cultures and smear microscopic examinations of the eyelid margin were conducted at the initial visit, after administering eye drops, and 1 month after the end of eye drop administration. The minimum inhibitory concentrations (MICs) of azithromycin were measured.

RESULTS

At the initial visit, the bacterial morphology determined by smear microscopic examinations coincided with that of strains isolated by culture taken from 22 of 45 patients. All detected bacteria were gram-positive, and Corynebacterium spp., Cutibacterium acnes, Staphylococcus epidermidis, Streptococcus spp., and Enterococcus faecalis were isolated most commonly. Compared with the initial visit the number of isolated strains per eye decreased significantly at 7 days after the start of eye drop administration and 1 month after the end of eye drop administration. The azithromycin MICs were temporarily increased after the start of eye drops but then decreased.

CONCLUSION

Our study suggests that in blepharitis pathogenicity is characterized by increased strain numbers and amounts of indigenous bacteria. Administering a 1% azithromycin ophthalmic solution suppresses the number of bacterial strains within 1 month after the end of eye drop administration without increasing drug resistance.

Therapie des Trockenen Auges

Die Therapie des Trockenen Auges stellt eine schwierige Aufgabe für den behandelnden Augenarzt dar. Fortschritte in unserem Verständnis der Risikofaktoren, der Ätiologie und Pathophysiologie des Trockenen Auges haben zu einer Weiterentwicklung der Behandlungsstrategien geführt. Vor Beginn der Therapie ist die korrekte Zuordnung in eine wässrig-muzinöse Tränenfilmdysfunktion (Mindersekretion), in eine lipidbedingte Tränenfilmdysfunktion (hyperevaporative Form durch eine abnormen Meibom-Drüsen-Physiologie) oder in eine variable Kombination wichtig. Unter Berücksichtigung aktueller Empfehlungen der DOG, des BVA und des TFOS DEWS II Unterausschusses wurde ein Behandlungsalgorithmus abgeleitet, der ein schrittweises Vorgehen je nach Schweregrad der Erkrankung darstellt.

Rabbit as an Animal Model for Ocular Surface Disease, Tear Osmolarity, Electrolyte, and Tear Ferning Profiles

SIGNIFICANCE

The tear film promotes ocular surface health and protection through its various constituents' functions. The application of methods for ocular surface examination is essential in the research of diseases that affect the tear film. Rabbits have been used as a model to study some human ocular diseases and to test ophthalmic products.

PURPOSE

The aim of the present study was to determine the biochemical profile, osmolarity, and tear ferning patterns of rabbit tears.

METHODS

Ten rabbits (Oryctolagus cuniculus) were evaluated for tear osmolarity, tear ferning types and grades (using Rolando and Masmali scales), and biochemical analysis of total protein, urea, and electrolytes (chloride, phosphorus, iron, sodium, potassium, and calcium).

RESULTS

Median ± semi-interquartile range for tear osmolarity was 283.5 ± 7.5 mOsm/L. Tear ferning test grades were type 1.0 ± 0.5 on the Rolando scale and 1.0 ± 0.5 on the Masmali scale. Type I and grade 1 were the most commonly observed ferning classifications (60 and 50%, respectively) for the rabbits' tears. Results for electrolytes and other biochemical compounds were as follows: total protein 4.40 g/dL, urea 130.60 mg/dL, chloride 196.51 mEq/L, phosphate 7.35 mg/dL, iron 95.76 μg/dL, sodium 202.04 mmol/L, potassium 12.74 mmol/L, and calcium 11.53 mg/dL.

CONCLUSIONS

The results of the various tests described herein may serve as a basis for research using rabbits as an ophthalmic disease model and in the development of diagnostic and therapeutic agents used for ocular health.

Efficacy of Azithromycin Eyedrops for Individuals With Meibomian Gland Dysfunction-Associated Posterior Blepharitis

PURPOSE

To examine the safety and efficacy of azithromycin eyedrops in Japanese individuals with meibomian gland dysfunction (MGD)-associated posterior blepharitis.

METHODS

Individuals with MGD-associated posterior blepharitis who visited the Itoh Clinic, Saitama, Japan, were randomly assigned to receive azithromycin (1%) eyedrops (AZM group, 16 eyes of 16 patients) or preservative-free artificial tears (control group, 20 eyes of 20 patients) for 2 weeks. All subjects also applied a warming eyelid compress twice per day. Subjective symptoms (Standardized Patient Evaluation of Eye Dryness [SPEED] score), lipid layer thickness (LLT) and interferometric pattern of the tear film, plugging and vascularity of the lid margin, noninvasive break-up time of the tear film (NIBUT) and fluorescein-based break-up time of the tear film (TBUT), corneal-conjunctival fluorescein staining score, tear meniscus height, meibum grade, meiboscore, tear osmolarity, and Schirmer test value were determined before and after treatment. Side effects of treatment were also recorded.

RESULTS

In the AZM group, SPEED score, LLT, interferometric pattern, plugging and vascularity of the lid margin, NIBUT, TBUT, meibum grade, and tear osmolarity were significantly improved after treatment compared with baseline. The SPEED score, interferometric pattern, plugging, vascularity, meibum grade, and tear osmolarity were also significantly improved after treatment in the AZM group compared with the control group. Common side effects in the AZM group were transient eye irritation and blurred vision.

CONCLUSION

Azithromycin eyedrops improved eyelid inflammation, the quality and quantity of the lipid layer of the tear film, and tear film stability. Such eyedrops thus seem to be a safe and effective treatment for MGD-associated posterior blepharitis.

Systematic review and meta-analysis of treating meibomian gland dysfunction with azithromycin

To systematically review studies of managing meibomian gland dysfunction (MGD) with azithromycin and pool clinical outcomes to show its effectiveness. Eligible studies were retrieved from five main electronic databases. Symptom score was the primary outcome, while clinical signs and objective measurements were secondary outcomes. Pooled rates for adverse events were also calculated. Improvements in each outcome after administering either oral azithromycin (OA) or topical azithromycin (TA) were pooled and measured by standard mean difference (SMD) to show the overall effectiveness. Then the effectiveness was sub-grouped by TA and OA. In addition, pooled outcomes after administering TA and oral doxycycline (OD) were compared with assess their effectiveness. Finally, 18 eligible studies were included. The overall pooled symptom scores were significantly reduced after administering both TA and OA [P < 0.0001; SMD = 1.54 (95% CI: 1.15–1.92)]. Similarly, the overall combined eyelid signs, plugging of the meibomian gland, meibum quality, and tear secretion were also distinctly improved. However, significant improvements for tear break-up time (TBUT) and corneal staining (CS) were achieved by TA (TBUT: P = 0.02; CS: P = 0.02) but not by OA (TBUT: P = 0.08; CS: P = 0.14). The pooled adverse event rates for TA and OA were 25% and 7%, respectively. Moreover, TA was comparable to OD to treat MGD regarding symptom score, TBUT and tear secretion. This study showed that MGD could be treated effectively with oral or topical azithromycin by improving symptoms, clinical signs, and stabilization of tear film. Topical azithromycin seemed to be superior over oral azithromycin or doxycycline in improving the quality of tear film in the short term.

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.

Use of topical bromfenac for treating ocular pain and inflammation beyond cataract surgery: a review of published studies

Topical ophthalmic nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to treat postoperative inflammation and pain following cataract surgery and for treatment and prophylaxis of pseudophakic cystoid macular edema (CME). Bromfenac is a brominated NSAID with strong in vitro anti-inflammatory potency. Like other ophthalmic NSAIDs, bromfenac is often used outside of the cataract surgery setting. This paper provides an overview of bromfenac’s preclinical ocular pharmacology and pharmacokinetics, followed by a review of 23 published clinical studies in which various marketed bromfenac formulations were used for conditions other than cataract surgery or pseudophakic CME. These include: post-refractive eye surgery; macular edema associated with diabetes, uveitis, or retinal vein occlusion; inflammation associated with age-related macular degeneration; pain related to intravitreal injections; and other ocular anterior segment and surface disorders with an inflammatory component. The published evidence reviewed supports the safety and effectiveness of bromfenac in these additional ophthalmic indications. Bromfenac was well tolerated when given alone or in combination with intravitreal anti-vascular endothelial growth factor agents, topical corticosteroids, or topical mast-cell stabilizers. The most common adverse event reported was ocular irritation. No serious adverse events (ie, corneal epithelial disorders) were reported, although the majority of studies did not systematically evaluate potential side effects. Corneal complications, such as melts reported with diclofenac and ketorolac, were not observed with bromfenac in the studies. In summary, published study data support the clinical utility of bromfenac in various ocular disorders beyond post-cataract surgery. Additional studies are warranted to further define the potential role of bromfenac ophthalmic solution in clinical practice.

Effect of cyclodextrin additives on azithromycin in aqueous solution and insight into the stabilization mechanism by sulfobutyl ether-β-cyclodextrin

The stability of azithromycin in buffered aqueous solution at pH 6.7 was investigated in the presence of different cyclodextrin (CD) additives by HPLC monitoring of the drug concentration over time. In the presence of γ-CDs, either in native or derivatized form, the long-term stability of azithromycin was sensibly decreased with respect to the reference sample without any additives, whereas the opposite effect was observed with all the three tested β-CDs. The most effective stabilization of the drug was obtained by using sulfobutyl ether-β-cyclodextrin, which allowed a concentration of azithromycin in solution at 99% up to 6 months at room temperature. The positive action of sulfobutyl ether-β-cyclodextrin was mainly exerted through the suppression of a degradation pathway leading to the opening of lactone ring of azithromycin. The formation of dynamic inclusion complexes in solution was ruled out by NMR data and stabilization of azithromycin by the amphiphilic sulfobutyl ether-β-cyclodextrin through surfactant-like effects was proposed on the basis of the strict similarity, either in the degradation profiles and in the NMR data, with a solution of the drug in the presence of sodium hexylsulphonate as surfactant.

Efficacy of azithromycin 1.5% eyedrops vs oral doxycycline in meibomian gland dysfunction: a randomized trial

PURPOSE

To determine the efficacy of azithromycin 1.5% eyedrops compared with oral doxycycline in patients with moderate to severe meibomian gland dysfunction (MGD).

METHODS

This prospective randomized trial included 169 participants with newly diagnosed moderate to severe MGD. Participants were randomly assigned to treatment with azithromycin 1.5% eyedrops (n = 85) twice daily for 2 days then once daily until 4 weeks or oral doxycycline (n = 84) 100 mg twice daily for 4 weeks. Signs and symptoms of MGD were evaluated at baseline and 4 weeks later. The percentages of participants with improvement in meibum quality were assessed as a primary outcome. Secondary outcomes were MGD-related symptoms, meibum expressibility, Oxford ocular surface staining score, tear film break up time (TBUT), and drug side effects.

RESULTS

Although there were significant improvements in all outcomes in both groups, there was no between-group differences in the percentages of participants with improved meibum quality (P = 0.80), MGD-related symptoms (P > 0.05), meibum expressibility (P = 0.92), Oxford ocular surface staining score (P = 0.59), and TBUT (P = 0.99). Five (5.88%) participants in azithromycin group and four (4.76%) participants in doxycycline group discontinued medications due to drug side effects (P = 0.75).

CONCLUSIONS

Both azithromycin 1.5% eyedrops and oral doxycycline significantly improved signs and symptoms in patients with moderate to severe MGD. Both azithromycin 1.5% eyedrops and oral doxycycline showed no difference in term of improved signs and symptoms of MGD as well as drug side effects that lead to discontinuation of medication.

Population Pharmacokinetic Modeling of Azithromycin Eyedrops in Tears Following Single-Dose Topical Administration in Healthy Volunteers

BACKGROUND AND OBJECTIVES

The disposition of azithromycin in the human eye following topical administration has not been fully explored. Population pharmacokinetic (PopPK) modeling can allow useful conclusions to be drawn based on limited tear sampling data. The aim of this study was therefore to develop and evaluate a PopPK model of azithromycin eyedrops in tears, investigate typical model parameters, and identify potential covariates following single-dose ocular instillation.

METHODS

A total of 84 tear samples were obtained from 42 healthy volunteers at seven time points over 24 h following topical administration of azithromycin eyedrops (2.5 mL/25 mg). Azithromycin concentrations in the tears were determined using a validated LC-MS/MS assay. PopPK analysis was performed using nonlinear mixed-effects modeling. Intraocular pressure, tear secretion measurement, age, and gender were evaluated as possible covariates. Bootstrap and visual predictive checks were used simultaneously to evaluate the PopPK model. The dosage regimen was further estimated based on Monte Carlo simulation and the area under the curve/minimal inhibitory concentration.

RESULTS

A linear two-compartment first-order elimination model was found to best describe the pharmacokinetic profile of azithromycin in tears. None of the covariates had a significant influence on the typical model parameters. The final PopPK model was demonstrated to be suitable and effective according to bootstrap and visual predictive checks. Twice-daily instillation of azithromycin eyedrops would appear to provide the required antibacterial activity.

CONCLUSION

A proposed linear two-compartment PopPK model of azithromycin eyedrops was found to be effective at describing the disposition of azithromycin in tears after ocular instillation.

Natamycin and Azithromycin Are Synergistic In Vitro against Ocular Pathogenic Aspergillus flavus Species Complex and Fusarium solani Species Complex Isolates

The interaction of natamycin-azithromycin combination against 60 ocular fungal isolates was tested in vitro The combination produced 100% synergistic interactions when natamycin was added to azithromycin 20, 40, and 50 μg/ml against Aspergillus flavus species complex (AFSC) isolates and to azithromycin 50 μg/ml against Fusarium solani species complex isolates. Addition of 50 μg/ml azithromycin enhanced natamycin's effect against AFSC isolates by reducing natamycin MIC₉₀ from 64 to 0.031 μg/ml. No antagonism was observed.

A comprehensive insight on ocular pharmacokinetics

The eye is a distinctive organ with protective anatomy and physiology. Several pharmacokinetics compartment models of ocular drug delivery have been developed for describing the absorption, distribution, and elimination of ocular drugs in the eye. Determining pharmacokinetics parameters in ocular tissues is a major challenge because of the complex anatomy and dynamic physiological barrier of the eye. In this review, pharmacokinetics of these compartments exploring different drugs, delivery systems, and routes of administration is discussed including factors affecting intraocular bioavailability. Factors such as precorneal fluid drainage, drug binding to tear proteins, systemic drug absorption, corneal factors, melanin binding, and drug metabolism render ocular delivery challenging and are elaborated in this manuscript. Several compartment models are discussed; these are developed in ocular drug delivery to study the pharmacokinetics parameters. There are several transporters present in both anterior and posterior segments of the eye which play a significant role in ocular pharmacokinetics and are summarized briefly. Moreover, several ocular pharmacokinetics animal models and relevant studies are reviewed and discussed in addition to the pharmacokinetics of various ocular formulations.

RETRACTED: Azithromycin 1.5% Ophthalmic Solution for Blepharitis Treatment: Comparison of 14- Versus 30-Day Treatment

The online-ahead-of-print published article, "Azithromycin 1.5% Ophthalmic Solution for Blepharitis Treatment: Comparison of 14- Versus 30-Day Treatment," by Altay Yesim, Demirok Gulizar, Balta Ozgur, and Bolu Hulya (DOI: 10.1089/jop.2015.0099) is being officially retracted from Journal of Ocular Pharmacology and Therapeutics (JOPT) due to post-publication authorship disputes and the discovery of simultaneous submission to both JOPT and the International Journal of Ophthalmology, which is a violation of the proper protocols of peer review. Journal of Ocular Pharmacology and Therapeutics and its editorial leadership are committed to maintaining the highest levels of scientific reporting and publishing, and therefore officially retracts the article based on the infringements listed herein.

Ocular Pharmacokinetics

Although the fundamental concepts of pharmacokinetics remain the same, ocular pharmacokinetics has its own challenges due to the uniqueness of barrier properties posed by various ocular tissues and its growing complexity with different routes of ocular administration. A thorough understanding of the barrier nature will aid in tailoring a drug or its carrier's physicochemical properties to its advantage. In order to deliver the right payload of a drug at the target site, various approaches can be taken to leverage the pharmacokinetics that includes molecular design based on desirable physicochemical properties, formulation approaches, and alternative routes of administration. In this chapter, a brief overview of the barrier properties with respect to various routes of administration is presented along with the physicochemical properties that influence the pharmacokinetics of ocular drugs. Recent advances in ocular pharmacokinetics are discussed in addition to new perspectives in interpreting existing data.

A randomized, double-masked, parallel-group, comparative study to evaluate the clinical efficacy and safety of 1% azithromycin-0.1% dexamethasone combination compared to 1% azithromycin alone, 0.1% dexamethasone alone, and vehicle in the treatment of subjects with blepharitis

Purpose

To evaluate the clinical efficacy and safety of a 1% azithromycin–0.1% dexamethasone combination in DuraSite (“combination”) compared to 0.1% dexamethasone in DuraSite, 1% azithromycin in DuraSite, and vehicle in the treatment of subjects with blepharitis.

Materials and methods

This was a Phase III, double-masked, vehicle-controlled, four-arm study in which 907 subjects with blepharitis were randomized to combination (n=305), 0.1% dexamethasone (n=298), 1% azithromycin (n=155), or vehicle (n=149). Ten study visits were scheduled: screening visit, days 1 and 4 (dosing phase) and 15, and months 1–6 (follow-up phase). On day 1, subjects applied one drop of the study drug to the eyelid of the inflamed eye(s) twice daily, and continued with twice-daily dosing for 14 days. After completing 14 days of dosing, subjects were followed for 6 months for efficacy and safety.

Results

A total of 57 subjects (6.3%) had complete clinical resolution at day 15: 25 (8.2%), 17 (5.7%), 8 (5.2%), and 7 (4.7%) subjects in the combination-, 0.1% dexamethasone-, 1% azithromycin-, and vehicle-treatment groups, respectively. The combination was superior to 1% azithromycin and vehicle alone, but not to 0.1% dexamethasone alone. Mean composite (total) clinical sign and symptom scores improved in all four treatment groups during the post-treatment evaluation phase for the intent-to-treat population, but outcomes were superior when a drop containing 0.1% dexamethasone was utilized. Clinical response was noted as early as day 4, and persisted as long as 6 months. Most adverse events were considered mild in severity and not related to the study drug.

Conclusion

A higher percentage of subjects in the combination group achieved complete clinical resolution of the signs and symptoms of blepharitis at day 15 than with 1% azithromycin and vehicle, but outcomes were similar to treatment with 0.1% dexamethasone alone. The combination was well tolerated.

The Effect of Intravitreal Azithromycin on the Albino Newborn Rabbit Retina

Purpose:

To evaluate the effect of intravitreal azithromycin on the retina in a newborn rabbit model.

Methods:

Twelve, two-week old New Zealand albino rabbits were divided into two groups (six in each). The right eyes of six rabbits received 0.75 mg (0.05 mL) azithromycin and the right eyes of the remaining six rabbits 1.5 mg (0.1 mL) azithromycin intravitreally. Left eyes were served as the control and received the same volume of saline. All eyes were enucleated at the third postinjection week. Retinal histology was examined by light microscopy. Apoptosis of the retinal cells was further evaluated by immunohistochemical staining for caspase-3 and in situ terminal deoxynucleotidyl transferase-mediated biotin-deoxyuridine triphosphate nick-end labeling (TUNEL) of DNA fragments.

Results:

Light microscopy demonstrated no retinal abnormalities in all eyes. However, retinal nuclear DNA fragmentation was evident in both study groups (33.6% with 1.5 mg and 21.4% with 0.75 mg azithromycin) with the TUNEL method. TUNEL staining ratio was statistically higher only in the second group treated with 1.5 mg azithromycin when compared to the control group (p=0.01 Mann Whitney U test). The ratio of caspase-3 positive cells in the two study groups was 21.5% and 20.2%, respectively. Caspase-3 staining ratio was statistically higher in both study groups when compared to the control eyes (p=0.00, p=0.00 respectively). The difference of TUNEL staining ratio between the two study groups was statistically significant (p=0.028), but there were no statistically significant differences in the two study groups by caspase-3 staining (p=0.247).

Conclusion:

In newborn rabbits, intravitreal azithromycin injection resulted in an apoptotic activity in the photoreceptor, bipolar and ganglion cells. Immunohistochemical analysis suggested that doses of 0.75 mg and 1.5 mg azithromycin, administered intravitreally might be toxic to the newborn rabbit retina.

Can tetracycline antibiotics duplicate the ability of azithromycin to stimulate human meibomian gland epithelial cell differentiation?

PURPOSE

Azithromycin and tetracyclines are commonly prescribed in the United States for the treatment of meibomian gland dysfunction (MGD). The efficacy of these antibiotics has been believed to be their antiinflammatory and antibacterial actions, which suppress MGD-associated posterior blepharitis and growth of lid bacteria. However, we recently discovered that azithromycin can act directly on human meibomian gland epithelial cells (HMGECs) to stimulate their function. In this study, we sought to determine whether tetracycline antibiotics can duplicate this azithromycin effect.

METHODS

Immortalized HMGEC were cultured in the presence of a vehicle, azithromycin, doxycycline, minocycline, or tetracycline for 5 days. Cells were evaluated for cholesterol and neutral lipid staining, and the lipid composition of cellular lysates was analyzed by high-performance thin-layer chromatography.

RESULTS

Our results demonstrate that azithromycin's ability to stimulate the differentiation of human meibomian gland cells is unique, and is not duplicated by doxycycline, minocycline, or tetracycline. Azithromycin, but not the other antibiotics, significantly increased the cellular accumulation of cholesterol, cholesterol esters, phospholipids, and lysosomes. These differentiative actions of azithromycin were paralleled by an increased expression of sterol regulatory element-binding protein 1.

CONCLUSIONS

Our findings show that the stimulatory effects of azithromycin on HMGEC function are unique and are not duplicated by the antibiotics doxycycline, minocycline, or tetracycline. Our results further suggest that this stimulatory influence of azithromycin may contribute to its beneficial effect in treating MGD and its associated evaporative dry eye disease.

Medical management of blepharitis

PURPOSE OF REVIEW

Blepharitis is one of the most common ocular pathologies encountered in the clinical setting. Despite its prevalence, successful treatment is often difficult. The purpose of this review is to provide an update on the medical management of blepharitis.

RECENT FINDINGS

The available treatment options for blepharitis have expanded rapidly in recent years. Eyelid hygiene remains the foundation of most treatment regimens, but the addition of topical and oral antibiotics, steroids, and calcineurin inhibitors is showing promising results. Dietary considerations and interventional procedures may also play a role in the future of blepharitis management.

SUMMARY

Although a curative therapy for blepharitis is unlikely in the near future, several novel treatment options may result in better control of this chronic condition.

Antibacterial efficacy of prophylactic besifloxacin 0.6% and moxifloxacin 0.5% in patients undergoing cataract surgery

Background

The purpose of this study was to investigate the ocular bacterial flora in patients scheduled to undergo cataract surgery and compare the antibacterial effects of besifloxacin ophthalmic suspension 0.6% and moxifloxacin ophthalmic solution 0.5% in these patients.

Methods

This was a prospective, randomized, laboratory-masked clinical trial. Patients received besifloxacin or moxifloxacin “quater in die” or QID (four times a day) for 3 days before cataract surgery in the surgical eye and 1 hour before surgery in the nonsurgical fellow eye. Conjunctival and eyelid swabs were obtained from both eyes at baseline and after treatment, on the day of surgery (Visit 2). Swabs were processed for bacterial colony counts (in terms of colony-forming units) and species identification. In vitro antibiotic susceptibilities of isolates were determined using Clinical and Laboratory Standards Institute breakpoints.

Results

Fifty-nine patients (n=28 besifloxacin, n=31 moxifloxacin) completed the study. The majority (73%) of conjunctival samples were culture negative at baseline. The most frequent isolates were coagulase-negative staphylococci (CoNS, 89%), specifically Staphylococcus epidermidis (72%). Both fluoroquinolones reduced the lid CFU values when administered QID for 3 days (P≤0.019), but only besifloxacin reduced the lid CFU estimate 1 hour following instillation of a single drop (P=0.039). Fewer besifloxacin-treated eyes had lids that were culture positive for CoNS at Visit 2 compared with moxifloxacin-treated eyes regardless of dosing regimen (P≤0.03). The minimum inhibitory concentration (MIC₉₀) of besifloxacin against methicillin-resistant S. epidermidis (MRSE) was eightfold lower than that of moxifloxacin.

Conclusion

Besifloxacin appeared more effective in reducing bacterial counts on eyelids of patients undergoing cataract surgery, with significant reductions as early as 1 hour postdose, compared with moxifloxacin. Besifloxacin was more active in vitro against MRSE.

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.

Treatment of blepharitis: recent clinical trials

Blepharitis is a chronic inflammatory disease of the eyelids that is frequently encountered in clinical practice. The etiology of the disorder is complex and not fully understood, but the general consensus is that bacteria and inflammation contribute to the pathology. Blepharitis can be classified into anterior blepharitis, involving the anterior lid margin and eyelashes, and posterior blepharitis, characterized by dysfunction of the meibomian glands. Long-term management of symptoms may include daily eyelid cleansing routines and the use of therapeutic agents that reduce infection and inflammation. A cure is not possible in most cases, and subjective symptoms may persist even when a clinical assessment of signs indicates that the condition has improved. There are no established guidelines regarding therapeutic regimens, but recent clinical trials have shown that antibiotics and topical corticosteroids can produce significant improvement in signs and symptoms of blepharitis. Fixed combinations of a topical antibiotic and a corticosteroid offer an effective and convenient treatment modality that addresses both infectious and inflammatory components of the disease. Further clinical trials are needed to determine optimal therapies for managing blepharitis.

Safety of besifloxacin ophthalmic suspension 0.6% in cataract and LASIK surgery patients

PURPOSE

The aim of the study was to evaluate the safety of besifloxacin ophthalmic suspension 0.6% as antibacterial prophylaxis in the surgical setting.

METHODS

Two prospective safety surveillance studies were conducted-one in the cataract surgery setting and the other in the laser-assisted in situ keratomileusis (LASIK) surgery setting. Cases from patients aged 18 years and above were eligible for inclusion. In both surveillance studies, data were collected from consecutive cases of routine primary cataract surgery and LASIK surgery, respectively, in which besifloxacin ophthalmic suspension 0.6% or moxifloxacin ophthalmic solution 0.5% was used as the topical perioperative prophylactic antibacterial medication as part of the clinician's routine standard of care. The primary safety endpoint was the incidence of treatment-emergent adverse events (TEAEs).

RESULTS

The cataract surgery surveillance study included 485 cases/eyes (besifloxacin, n = 333; moxifloxacin, n = 152), whereas the LASIK surveillance study included 456 cases/eyes (besifloxacin, n = 344; moxifloxacin, n = 112). In the cataract study, only 1 TEAE was reported in a besifloxacin case (mild hypersensitivity/allergic reaction considered possibly related to besifloxacin). No TEAEs were reported in the LASIK study. In both studies, surgical outcomes were similar with both treatments. The frequency of preoperative and/or postoperative dosing was generally lower for besifloxacin than that for moxifloxacin.

CONCLUSIONS

In prospective safety surveillance studies of patients undergoing cataract extraction or LASIK, TEAEs associated with prophylactic use of besifloxacin ophthalmic suspension 0.6% were rare, and surgical outcomes with besifloxacin were similar to those with moxifloxacin ophthalmic solution 0.5%.

Prolonged exposure to loteprednol etabonate in human tear fluid and rabbit ocular tissues following topical ocular administration of Lotemax gel, 0.5%

PURPOSE

A new gel formulation containing loteprednol etabonate (LE), a C-20 ester corticosteroid used to treat ocular inflammation, was developed to provide increased retention on the ocular surface for improved drug delivery to intraocular tissues. This investigation evaluated concentrations of LE in tear fluid following topical instillation of LE gel to humans and the ocular and systemic pharmacokinetics of LE following administration to rabbits.

METHODS

LE ophthalmic gel 0.5% was administered as a single topical dose to human volunteers (n=12) and Dutch Belted rabbits (n=40). In the human study, tear sampling was performed at 6, 9, 12, and 24 h after instillation. In the rabbit study, tears and ocular tissues were collected from 5 min through 24 h postdose. Serial blood samples were collected from one cohort of rabbits for plasma analysis. Concentrations of LE were determined by high performance liquid chromatography tandem mass spectrometry.

RESULTS

In humans, LE was detected in tears at all the time points assessed with mean concentrations of 114 μg/g at 6 h declining to 2.41 μg/g at 24 h postdose. In rabbits, LE was detected in all ocular tissues within 5 min after dosing. Maximum concentrations of LE were achieved within 0.5 h and were highest in tear fluid (1560 μg/g), followed by bulbar conjunctiva (4.03 μg/g), cornea, (2.18 μg/g), iris/ciliary body (0.162 μg/g), and aqueous humor (0.0138 μg/mL). LE remained measurable in all ocular tissues through 24 h with the exception of aqueous humor. In contrast, plasma levels of LE were low with no detectable levels after 4 h.

CONCLUSIONS

The gel formulation of LE provided prolonged exposure to LE on the ocular surface, with measurable levels in tears through 24 h in both humans and rabbits, for delivery of LE to anterior segment tissues, as evidenced by sustained levels of LE in rabbit conjunctiva, cornea, and iris/ciliary body.

Topical azithromycin as a novel treatment for ocular rosacea

PURPOSE

Acne rosacea is a common dermatological conditions associated with blepharitis. Current treatments include artificial tears, lid hygiene, and systemic doxycycline. In this study the authors evaluate the effectiveness of topical azithromycin in ocular rosacea.

METHODS

The authors enrolled 37 ocular rosacea patients: 12 were treated with systemic doxycycline, 16 with azithromycin eyedrops, and 9 did not receive medical treatments. Ocular signs and symptoms and side effects were evaluated at baseline and at 1-month follow-up.

RESULTS

A significant improvement in TF-BUT, meibomian gland plugging, and Oxford score associated with symptom reduction was reported by all patients after 1 month. All treatments were well tolerated, with mild gastro-intestinal symptoms in 33% of the doxycycline group and mild burning after instillation in the azithromycin group.

CONCLUSIONS

Topical azithromycin may represent an additional treatment for ocular rosacea, with a shorter duration of treatment and absence of gastrointestinal side effects as compared to systemic doxycycline.

Efficacy of azithromycin 1.5% eye drops in childhood ocular rosacea with phlyctenular blepharokeratoconjunctivitis

Background

The purpose of this study is to report the efficacy of azithromycin 1.5% eye drops in children with ocular rosacea and phlyctenular blepharokeratoconjunctivitis. This retrospective study from January 2009 to March 2010 included 16 children treated with lid hygiene plus azithromycin 1.5% eye drops (Azyter®): 3-day treatments (1 drop twice a day) every 10 days, reduced based on efficacy to one treatment every 15 days and then to one treatment per month.

Results

Nineteen eyes of six boys and ten girls, aged 4 to 16 years (mean, 9.3 ± 4.0) were included. The disease was previously resistant to lid hygiene (all the patients), oral erythromycin (one patient), and intermittent topical steroids (six patients). The median duration of each phase of azithromycin treatment (i.e., three, two, and one treatments per month) was 2 months. Ocular inflammation was controlled by azithromycin alone in 15 patients. In one uncontrolled case, cyclosporine 2% eye drops was added at month 5. Bulbar conjunctival hyperemia resolved completely within 1 month in all eyes, whereas conjunctival phlyctenules and corneal inflammation took longer to improve, with a complete resolution within 3 to 10 months. Blepharitis grade decreased from 2.31 ± 0.79 to 1.50 ± 0.73. Treatment was stopped after a median of 6 months (from 4 to 10 months) without recurrence of corneoconjunctival inflammation (median follow-up without treatment, 11 months). Six cases of ocular irritation were reported, two of which led to treatment withdrawal.

Conclusion

Azithromycin 1.5% eye drops is an effective treatment for phlyctenular keratoconjunctivitis complicating childhood ocular rosacea.

Besifloxacin ophthalmic suspension 0.6% in the treatment of bacterial conjunctivitis patients with Pseudomonas aeruginosa infections

Background

The purpose of this study was to determine the efficacy of besifloxacin ophthalmic suspension 0.6% when used in the treatment of bacterial conjunctivitis infections due to Pseudomonas aeruginosa.

Methods

We undertook a post hoc analysis of clinical outcomes in patients with bacterial conjunctivitis due to P. aeruginosa across four prospective, multicenter, double-masked, randomized, controlled, clinical studies of besifloxacin ophthalmic suspension 0.6%. Efficacy outcomes included bacterial eradication and clinical resolution of the baseline infection at follow-up visits. Bacterial eradication was defined as the absence of ocular bacterial species present at or above threshold at baseline, while clinical resolution was defined as grade 0 ocular discharge and bulbar conjunctival injection. Safety outcomes included the incidence of adverse events, changes in visual acuity, and biomicroscopy and ophthalmoscopy findings. Patient outcomes were summarized and bacterial eradication and clinical resolution rates integrated.

Results

Of 1317 patients with culture-confirmed bacterial conjunctivitis across four clinical studies, nine (0.7%) were infected with P. aeruginosa at baseline, and of these, five were randomized to treatment with besifloxacin ophthalmic suspension 0.6%. Bacterial eradication of the baseline infection was observed at both follow-up visits in all five patients. Clinical resolution was achieved in two of five patients by the first follow-up visit and four of five patients by the second follow-up visit. There were no adverse events reported in these patients. There were no clinically meaningful biomicroscopy findings or changes in ophthalmoscopy or visual acuity.

Conclusion

The incidence of bacterial conjunctivitis due to P. aeruginosa was low. Treatment of patients with P. aeruginosa infections with besifloxacin ophthalmic suspension 0.6% led to bacterial eradication of P. aeruginosa by the first follow-up visit and high rates of clinical resolution.

Recent advances in ophthalmic drug delivery

Topical ocular drug bioavailability is notoriously poor, in the order of 5% or less. This is a consequence of effective multiple barriers to drug entry, comprising nasolacrimal drainage, epithelial drug transport barriers and clearance from the vasculature in the conjunctiva. While sustained drug delivery to the back of the eye is now feasible with intravitreal implants such as Vitrasert (-6 months), Retisert (-3 years) and Iluvien (-3 years), currently there are no marketed delivery systems for long-term drug delivery to the anterior segment of the eye. The purpose of this article is to summarize the resurgence in interest to prolong and improve drug entry from topical administration. These approaches include mucoadhesives, viscous polymer vehicles, transporter-targeted prodrug design, receptor-targeted functionalized nanoparticles, iontophoresis, punctal plug and contact lens delivery systems. A few of these delivery systems might be useful in treating diseases affecting the back of the eye. Their effectiveness will be compared against intravitreal implants (upper bound of effectiveness) and trans-scleral systems (lower bound of effectiveness). Refining the animal model by incorporating the latest advances in microdialysis and imaging technology is key to expanding the knowledge central to the design, testing and evaluation of the next generation of innovative ocular drug delivery systems.

Nontuberculous mycobacterial ocular and adnexal infections

The nontuberculous (also called "atypical") mycobacteria have become increasingly important causes of systemic as well as ocular morbidity in recent decades. All ocular tissues can become infected with these organisms, particularly in patients who are predisposed following ocular trauma, surgery, use of corticosteroids, or are immunocompromised. Because of their relative resistance to available antibiotics, multidrug parenteral therapy continues to be the mainstay of treatment of more serious ocular and adnexal infections caused by nontuberculous mycobacteria (NTM). Periocular cutaneous, adnexal, and orbital NTM infections remain rare and require surgical debridement and long-term parenteral antibiotic therapy. NTM scleritis may occur after trauma or scleral buckling and can cause chronic disease that responds only to appropriate antibiotic therapy and, in some cases, surgical debridement and explant removal. NTM infectious keratitis following trauma or refractive surgical procedures is commonly confused with other infections such as Herpes simplex keratitis and requires aggressive topical therapy and possible surgical debridement, particularly in those cases occuring after laser in situ keratomileusis. Only 18 cases of endophthalmitis due to NTM have been reported. Systemic and intraocular antibiotic therapy and multiple vitrectomies may be needed in NTM endophthalmitis; the prognosis remains poor, however. Disseminated NTM choroiditis in acquired immune deficiency syndrome patients with immune reconstitution during highly active anti-retroviral therapy is a rare infection that can present as a necrotizing chorioretinitis with dense vitritis, mimicking many other entities and needs to be recognized so that timely, life-saving treatment can be administered. Regardless of which ocular tissue is infected, all NTM ocular infections present similar challenges of recognition and of therapeutic intervention. We clarify diagnosis and delineate modern, effective therapy for these conditions.

Review of Azithromycin Ophthalmic 1% Solution (AzaSite(®)) for the Treatment of Ocular Infections

AzaSite(®) (azithromomycin 1.0%) ophthalmic solution was approved in 2007 by the US Food and Drug Administration (FDA) as the first commercially available formulation of ophthalmic azithromycin for the treatment of bacterial conjunctivitis. AzaSite(®) utilizes a vehicle delivery system called DuraSite(®), which stabilizes and sustains the release of azithromycin to the ocular surface, leading to a longer drug residence time, less frequent dosing, and an increase in patient compliance. AzaSite(®) is a broad spectrum antibiotic, effective against Gram-positive, Gram-negative, and atypical bacteria. AzaSite(®) has been studied for the treatment of ocular conditions beyond its clinical indication. A number of clinical studies have evaluated its efficacy and safety in the management of ocular conditions such as bacterial conjunctivitis and blepharitis on both the pediatric and adult populations. This article aims to evaluate the peer-reviewed published literature on the use of azithromycin 1.0% ophthalmic for current and possible future ophthalmic uses.

Update and critical appraisal of the use of topical azithromycin ophthalmic 1% (AzaSite) solution in the treatment of ocular infections

Azithromycin is an azalide that acts by binding to the 50S ribosomal subunit of susceptible microorganisms and interfering with microbial protein synthesis. Azithromycin is also noted by anti-inflammatory and immunomodulatory activity. AzaSite^® (Inspire Pharmaceuticals, Inc, Durham, NC) is azithromycin ophthalmic solution, 1% formulated in polycarbophil (the aqueous mucoadhesive polymer contained in DuraSite^®) that delivers high and prolonged azithromycin concentrations in a variety of ocular tissues, including the conjunctiva, cornea and particularly the eyelid. AzaSite was approved by the Food and Drug Administration (FDA) in the US in 2007, for the treatment of bacterial conjunctivitis caused by susceptible isolates. This article aims to evaluate the peer-reviewed published scientific literature and to define well-established uses of AzaSite eye drops in the field of ocular infections.

Effect of topical azithromycin on corneal innate immune responses

PURPOSE

To determine the effect of azithromycin (AZM) in a murine model of corneal inflammation.

METHODS

The effect of topical AZM was studied in murine corneal inflammation. Corneal inflammation was induced by thermal cautery in BALB/c mice. Leukocyte infiltration at different time points was analyzed by flow cytometry. At set time points, real-time polymerase chain reaction was performed to quantify the expression of different inflammatory cytokine transcript in the cornea. Corneal samples were analyzed immunohistochemically for the expression of intercellular adhesion molecule-1 (ICAM-1). Corneal neovascularization (CNV) was induced by micropellet (VEGF-A) placement. Mice were then treated topically with either AZM or vehicle. CNV was evaluated morphometrically.

RESULTS

Eyes receiving AZM showed a significant decrease in corneal infiltration compared with the vehicle-treated group. AZM also significantly decreased messenger RNA expression levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and ICAM-1 in the cornea. There was no significant difference in CNV between the AZM- and vehicle-treated groups.

CONCLUSIONS

After an inflammatory insult, topical AZM significantly reduced leukocyte infiltration into the cornea. This was further supported by an associated decrease in expression of IL-1β, TNF-α, and ICAM-1 in the cornea, indicating AZM may have a potential anti-inflammatory effect on corneal inflammation.

Pharmacokinetics of azithromycin and moxifloxacin in human conjunctiva and aqueous humor during and after the approved dosing regimens

PURPOSE

To evaluate the ocular pharmacokinetics of azithromycin and moxifloxacin in human conjunctiva and aqueous humor in subjects undergoing cataract surgery.

DESIGN

Multicenter, open-label, randomized study.

METHODS

Subjects scheduled for routine cataract surgery and with normal-appearing conjunctiva were eligible. One conjunctival biopsy sample and 1 aqueous humor sample were obtained from subjects randomly assigned to 1 of 10 prespecified time points (1 to 312 hours) after treatment initiation of azithromycin ophthalmic solution 1% or moxifloxacin ophthalmic solution 0.5%. Samples were assayed using liquid chromatography tandem mass spectrometry.

RESULTS

Azithromycin 1% provided high concentrations (peak level, 559.7 μg/g) in human conjunctiva that were sustained at levels 1 to 2 orders of magnitude higher than those of moxifloxacin 0.5% throughout the 7-day dosing period and for at least 7 days thereafter. Azithromycin also showed an extended half-life (65.7 hours) in conjunctiva relative to that of moxifloxacin (28.6 hours). Accordingly, the concentration of azithromycin was maintained well above the minimum inhibitory concentration required for inhibition of growth of 90% of tested bacterial isolates for at least 7 days, whereas moxifloxacin conjunctival levels fell to levels at or less than the minimum inhibitory concentration required for inhibition of growth of 90% of tested bacterial isolates approximately 24 hours after the last dose. Peak aqueous humor concentration of moxifloxacin was higher (0.77 μg/mL) than that of azithromycin (0.053 μg/mL). No clinically relevant safety findings were observed.

CONCLUSIONS

Azithromycin 1% demonstrated high, therapeutic levels in the conjunctiva that were maintained up to 7 days after completion of a 1-week dosing regimen. Aqueous humor levels, however, were subtherapeutic with this dosing regimen. In comparison, moxifloxacin achieved lower conjunctival tissue levels, but higher aqueous humor levels.