The Cytotoxic Effects of Preserved and Preservative-Free Prostaglandin Analogs on Human Corneal and Conjunctival EpitheliumIn Vitroand the Distribution of Benzalkonium Chloride Homologs in Ocular Surface TissuesIn Vivo

From Eye Care to Hair Growth: Bimatoprost

BACKGROUND

Bimatoprost has emerged as a significant medication in the field of medicine over the past several decades, with diverse applications in ophthalmology, dermatology, and beyond. Originally developed as an ocular hypotensive agent, it has proven highly effective in treating glaucoma and ocular hypertension. Its ability to reduce intraocular pressure has established it as a first-line treatment option, improving management and preventing vision loss. In dermatology, bimatoprost has shown promising results in the promotion of hair growth, particularly in the treatment of alopecia and hypotrichosis. Its mechanism of action, stimulating the hair cycle and prolonging the growth phase, has led to the development of bimatoprost-containing solutions for enhancing eyelash growth.

AIM

The aim of our review is to provide a brief description, overview, and studies in the current literature regarding the versatile clinical use of bimatoprost in recent years. This can help clinicians determine the most suitable individualized therapy to meet the needs of each patient.

METHODS

Our methods involve a comprehensive review of the latest advancements reported in the literature in bimatoprost formulations, which range from traditional eye drops to sustained-release implants. These innovations offer extended drug delivery, enhance patient compliance, and minimize side effects.

RESULTS

The vast literature published on PubMed has confirmed the clinical usefulness of bimatoprost in lowering intraocular pressure and in managing patients with glaucoma. Numerous studies have shown promising results in dermatology and esthetics in promoting hair growth, particularly in treating alopecia and hypotrichosis. Its mechanism of action involves stimulating the hair cycle and prolonging the growth phase, leading to the development of solutions that enhance eyelash growth. The global use of bimatoprost has expanded significantly, with applications growing beyond its initial indications. Ongoing research is exploring its potential in glaucoma surgery, neuroprotection, and cosmetic procedures.

CONCLUSIONS

Bimatoprost has shown immense potential for addressing a wide range of therapeutic needs through various formulations and advancements. Promising future perspectives include the exploration of novel delivery systems such as contact lenses and microneedles to further enhance drug efficacy and patient comfort. Ongoing research and future perspectives continue to shape its role in medicine, promising further advancements and improved patient outcomes.

Pharmacokinetic and Ocular Toxicity Evaluation of Latanoprost Ophthalmic Solution, 0.005%, with Preservative Level Reduced to Below the Limit of Quantitation

Purpose: The systemic and ocular pharmacokinetics (PK), and ocular toxicity of benzalkonium chloride (BAK)-free TearClear latanoprost ophthalmic solution, 0.005% formulation (TC-002) were evaluated. TC-002 is designed to selectively capture BAK at the time of drug administration; therefore, the dose delivered to the eye contains no quantifiable level of preservative. Methods: The systemic and ocular PK of TC-002 were compared to a BAK containing reference listed drug (RLD, Xalatan™) over a 24-h period, after a single topical ocular dose to 1 eye of male Dutch Belted (DB) rabbits (n = 3/timepoint). Latanoprost acid concentrations were measured in plasma and ocular tissues. The ocular toxicity was evaluated in a separate study and included toxicokinetic evaluation of TC-002 after once daily topical ocular dosing into each eye of DB rabbits (n = 8/group) for at least 28 days. Toxicity endpoints included ophthalmic and clinical evaluations, necropsy, and microscopic evaluation of ocular tissues. Results: Average ratios of Cmax values for TC-002/RLD ranged from 0.6 to 1.6, and Cmax and area under the concentration-time curve of last observed concentration (AUClast) exposures to latanoprost acid were similar (<2-fold) between the 2 treatments. In the 28-day study, the Tmax was achieved in both groups in <0.5 h. There were no abnormal ocular findings. Conclusions: TC-002 with no quantifiable preservative or BAK-containing RLD exhibited similar ocular and systemic PK profiles. TC-002 was well tolerated and comparable to RLD. TC-002 retains the safety and PK characteristics of RLD without the added concern of long-term exposure of the eye to preservatives.

The molecular aspect of anti-glaucomatous eye drops - are we harming our patients?

Glaucoma is one of the leading causes of irreversible blindness. Progression is halted with a reduction in intraocular pressure (IOP), which is most often achieved with eye drops. A major challenge in the topical treatment of glaucoma patients is the many side effects and the resulting reduced adherence. Side effects may of course be due to the molecular properties of the active pharmaceutical ingredients (APIs). There are currently six different APIs available: prostaglandin analogues, β-adrenergic inhibitors, α-adrenergic agonists, carbonic anhydrase inhibitors, rho-kinase inhibitors and muscarinic 3 agonists. But the additives used in eye drops are also known to cause damage to the ocular surface and to some extent also to the deeper tissues. Said additives are considered inactive molecular components and are added to secure for instance viscosity and pH value, and to prevent contamination. There has been an increasing focus on the harmful effects of preservatives, with the most commonly used preservative benzalkonium chloride (BAK) being particularly controversial. BAK has long been recognized as a toxin that increases the risk of ocular discomfort. This can affect the adherence and ultimately result in lack of disease control. Other issues include the addition of certain buffers, such as phosphates, and varying pH values. This review will address the different molecular components of the IOP-lowering eye drops and what to be aware of when prescribing topical glaucoma treatment.

Ocular surface disease signs and symptoms of glaucoma patients and their relation to glaucoma medication in Finland

PURPOSE

To evaluate the prevalence of ocular surface disease (OSD) signs and symptoms of glaucoma patients in private clinics in relation to topical glaucoma treatment and to compare them to non-glaucomatous population.

METHODS

A multicenter, cross-sectional study consisting of private ophthalmology clinic visits in southern Finland. Glaucoma patients had a diagnosis of primary open-angle glaucoma, pseudoexfoliation glaucoma, pigmentary glaucoma, or treated ocular hypertension. Control patients had no prior or current use of glaucoma medication. Recorded parameters included OSD signs and symptoms, used glaucoma medications during the past 6 months, and the product name, type, and duration of used antiglaucoma drugs.

RESULTS

Glaucoma patients (n = 564) showed higher severity of OSD sign parameters excluding Schirmer's test, as well as increased dry eye sensation compared to controls (n = 51). Beta-blockers and preservative-free prostaglandins had the smallest effect on all parameters. The increasing number of active compounds and administered eye drops per day showed an association with increasing severity of OSD signs, as well as dry eye and foreign body sensation. Duration of glaucoma medication showed no significant association with OSD signs or symptoms.

CONCLUSION

Glaucoma patients show higher prevalence of OSD signs and dry eye sensation compared to non-glaucomatous population. The use of preserved glaucoma medication, as well as high number of active compounds and eye drops increase the severity of these parameters. There are significant differences between the types of glaucoma medication used, and therefore the selection of them is important especially in patients suffering from OSD.

A novel ophthalmic latanoprost 0.005% nanoemulsion: a cytotoxicity study

BACKGROUND

Benzalkonium chloride (BAK), the most commonly used preservative in anti-glaucoma eye drops, inflicts damage to the ocular surface. A novel anti-glaucoma formulation that avoids the use of BAK has been developed. The aim of this study was to evaluate the cytotoxicity of this formulation and to compare it with an ophthalmic solution containing BAK.

METHODS

Two different latanoprost eye drops were used: one ophthalmic solution (LSc) containing BAK 0.02% and one ophthalmic nanoemulsion (LNe) with a soft preservative (potassium sorbate 0.18%). Human epithelial conjunctival cells were incubated for 15, 30, and 60 min with either LSc or LNe. The cytotoxicity was determined by MTT assay. Cell death was measured by flow cytometry using annexin V-FITC and propidium iodide.

RESULTS

The values of cell viability and proliferation obtained from cells exposed to LNe were between 80 and 90% relative to the control group, whereas values obtained from cells exposed to LSc were around 30% at all study times (p < 0.05 at 15 and 30 min; p < 0.01 at 60 min). The percentage of viable cells decreased significantly when cells were incubated with LSc compared with cells incubated with LNe at all the study times, while the percentage of cells in late apoptosis/necrosis increased significantly in cells exposed to LSc compared to LNe.

CONCLUSIONS

The new latanoprost nanoemulsion is significantly less cytotoxic on human conjunctival cells than LSc. These results suggest that the new formulation might be gentler on the eye surface than currently available BAK-preserved latanoprost solutions.

Effect of travoprost, latanoprost and bimatoprost PGF2α treatments on the biomechanical properties of in-vivo rabbit cornea

Prostaglandin F2α analogues (PGF2α), one of the most commonly prescribed classes of hypotensive agents, could decrease collagen fibril density and remodel the extracellular matrix in cornea. We hypothesized that PGF2α's would induce corneal softening, reduce the accuracy of intraocular pressure (IOP) measurement and lead to uncertainty in the effectiveness of the therapy. We determined the stress-strain behavior of rabbit cornea after PGF2α usage and evaluated the effect of biomechanical changes associated with PGF2α treatment on IOP measurements by Goldmann Applanation Tonometry (GAT). The tangent modulus decreased after PGF2α treatment, while the stromal interfibrillar spacing increased. PGF2α was shown to also affect the lateral eye with lower effect, which did not undergo direct eyedrop treatment. Significant decreases in the numerical predictions of GAT-IOP were predicted in all treated groups relative to control groups. Different PGF2α's (travoprost, latanoprost and bimatoprost) were associated with different extents of reduction in tissue stiffness and changes in corneal microstructure. PGF2α-induced changes in corneal mechanical properties could reduce the accuracy of IOP measurement and may cause an overestimation of the effect of PGF2α in lowering IOP, possibly leading to uncertainties in glaucoma management.

Changes in Corneal Biomechanical Properties in PRK Followed by Two Accelerated CXL Energy Doses in Rabbit Eyes

PURPOSE

To evaluate whether photorefractive keratectomy (PRK) combined with the two commonly delivered energy doses in accelerated corneal cross-linking (A-CXL) could help the cornea maintain its preoperative stiffness level.

METHODS

A total of 72 corneas of 36 healthy white Japanese rabbits were randomly divided into four equal groups. The groups included an untreated control group and three that had undergone PRK. After tissue ablation, one of the latter three groups (PRK group) was left untreated, whereas the other two were exposed to riboflavin (0.22% concentration by volume) and ultraviolet-A (370 nm) with the same irradiation (30 mW/cm2) but different CXL energy doses of 1.8 J/cm2 (PXL group) and 2.7 J/cm2 (PXH group). Dynamic Scheimpflug analyzer (Corvis ST; Oculus Optikgeräte GmbH) measurements of stiffness parameter at first applanation (SP-A1), Stress-Strain Index (SSI), and other dynamic corneal response parameters were taken 3 days preoperatively and 1 month postoperatively. Subsequently, ex vivo inflation testing was performed and the tangent modulus of each specimen was estimated using an inverse analysis process.

RESULTS

In comparison to the control group, the tangent modulus at a stress of 10 kPa decreased by 8.9% in the PRK group and increased by 10.6% and 22.4% in the PXL and PXH groups, respectively. SP-A1 decreased postoperatively in the PRK group (P < .05), indicating an overall stiffness reduction of -7.4, -3.5, and -5.3 mm Hg/mm in PRK, PXL, and PXH groups, respectively. The material stiffness parameter SSI remained almost unchanged in the PRK group (P = .989), increased slightly in the PXL group (8.3%, P = .077), and increased significantly in the PXH group (11.1%) (P < .05).

CONCLUSIONS

Biomechanical deterioration following PRK was significant and could not be fully compensated for by ACXL with either 1.8 or 2.7 J/cm2 doses. The increased value of corneal overall stiffness was higher in A-CXL with 2.7 J/cm2 energy than with 1.8 J/cm2 energy. [J Refract Surg. 2021;37(12):853-860.].

The treatment of glaucoma using topical preservative-free agents: an evaluation of safety and tolerability

Introduction: Preservative-free (PF) medications represent a valuable treatment strategy in the lifelong management of glaucoma. By removing preservative toxicity, PF formulations provide tangible clinical benefits to glaucoma patients worldwide. They improve tolerability and adherence, leading to a positive impact in long-term intraocular pressure (IOP) control.Areas covered: A critical review of the subject is provided, including selected evidence on the safety and tolerability of currently available topical PF formulations. Cumulative evidence confirms that topical PF medications are at least equally efficacious to their preserved equivalents. There is convincing short-term evidence for superior tolerability and safety of PF formulations compared to preserved medications. The long-term benefits and success of PF therapy requires further elucidation.Expert opinion: Successful stepwise administration of medical therapy for glaucoma remains elusive. There is a greater risk for ocular toxicity and therapy failure with preserved topical glaucoma therapy. Currently available and emerging PF therapy options potentially optimize lifelong stepwise glaucoma therapy and may enhance outcome. To avert complications from preservatives leading to poor adherence, ideally, future antiglaucoma therapy should become 100% PF. There are still key aspects of PF therapy that warrant further investigation.

Biomechanical Effects of Two Forms of PGF2α on Ex-vivo Rabbit Cornea

PURPOSE

To investigate the biomechanical effects of two synthetic prostaglandin F2α analogues (PGF2α), namely Travoprost and Tafluprost, on the ex-vivo rabbit cornea.

MATERIALS AND METHODS

Ninety-six eyes of 48 Japanese white rabbits were divided into 3 equal groups randomly; the Travoprost treated group (Tra), the Tafluprost treated group (Taf) and the control group (Co). Eyes in Tra and Taf groups were preserved in storage medium for 10 days with 1:10 Travoprost and Tafluprost diluents, respectively; while the Co eyes were preserved in a similar but PGF2α-free medium. Twenty-four corneas of each group were tested under inflation conditions with up to 30 mmHg posterior pressure. The pressure-deformation data obtained experimentally were used in an inverse analysis process to derive the stress-strain behavior of the tissue, using which the tangent modulus, a direct measure of the tissue's material stiffness, was calculated. The remaining eight specimens of each group were analyzed using electron microscopy for fibril diameter and interfibrillar spacing.

RESULTS

Although the central corneal thickness increased significantly in the three groups after storage (p < .01), it was similar in all groups both before (p = .598) and after storage (p = .181). After treatment with Travoprost and Tafluprost, the corneas exhibited lower tangent modulus (by 29.2% and 29.8%, respectively, at 6 kPa stress) and larger stromal interfibril spacing (by 21.9% and 23.6%) compared with the control group. There was no significant change in fibril diameter with either Travoprost or Tafluprost treatment (p = .769).

CONCLUSIONS

The results demonstrated significant reductions in tangent modulus and increases in interfibrillar spacing, which were of similar magnitudes, with the application of two different forms of PGF2α.

Profiling ocular surface responses to preserved and non-preserved topical glaucoma medications: A 2-year randomized evaluation study

BACKGROUND

Use of topical glaucoma medications has been reported to cause ocular surface (OS) discomfort and inflammation. This study explores the profile of inflammatory cytokines and OS symptoms induced in response to preserved and non-preserved drops.

METHODS

Prospective, randomized evaluation on 36 treatment-naïve patients over 24 months of three differently preserved glaucoma drop preparations: Preservative-free (PF), polyquad (PQ) and benzalkonium chloride (BAK). Study participants were evaluated at baseline and then at 1, 3, 6, 12 and 24 months while on medication. At each visit, participants completed the OS disease index (OSDI) questionnaire, had basal tear sampling and impression cytology (IC) of the conjunctival epithelium. Quantitative polymerase chain reaction was performed to measure the gene expression of inflammatory cytokines [interleukin (IL)-6, IL-8, IL-10, IL-12A, IL-12B, IL-17A, IL-1β and tumour necrosis factor-α] in the IC samples. Corresponding protein expression of cytokines in tear samples was assessed by the Becton-Dickinson cytometric bead arrays.

RESULTS

Compared to PF and PQ groups, mRNA and protein expression of IL-6, IL-8 and IL-1β increased in samples from the BAK group in a time-dependent fashion, whereas all other cytokines showed a non-significant increase. In the BAK group, there was a strong correlation between OSDI and the levels of IC/IL-1β (r = .832, R² = .692 and P = .040); IC/IL-10 (r = .925, R² = .856 and P = .008) and tear/IL-1β (r = .899, R² = .808 and P = .014).

CONCLUSIONS

BAK-preserved topical drops stimulate a sterile inflammatory response on the OS within 3 months which is maintained thereafter, whereas PF-drops and PQ-preserved drops showed no significant OS inflammation.

Corneal damage and its recovery after instillation of preservative-free versus preserved latanoprost eye drops

Purpose: Latanoprost ophthalmic solution is highly effective as a therapeutic agent for glaucoma and is applied worldwide. However, harmful effects on the corneal surface have been reported regarding the commercially available latanoprost ophthalmic solution. Corneal surface toxicity may be caused by the added preservative of the ophthalmic solution. In order to ascertain whether latanoprost itself can damage the cornea or if this is solely due to the added preservatives, this study attempted to determine the corneal changes that occur at different time periods following usage of preservative-free versus preserved latanoprost eye drops.Materials and methods: Preservative-free latanoprost eye drops (Monoprost^®) or preserved latanoprost eye drops (Xalatan^®) containing 0.02% benzalkonium chloride (BAC) were instilled in the corneas of rabbits. For each of the two different eye drop solutions, the rabbits used in this experiment were divided into three exposure groups: 1 minute, 24 hour, and 1 week groups. Corneal transepithelial electrical resistance (TER) and scanning electron microscopy (SEM) were examined immediately (1 minute) after instillation, at 24 hours after instillation, and at 24 hours after 1 week of daily instillations of latanoprost. Hank's balanced salt solution was used in the control group.Results: The mean corneal TER of the control group was 933.8 ± 279.0 Ω cm². In preservative-free latanoprost instilled corneas, there was no significant decrease in the TER or morphological changes at any of the time points, with the relative TER values of 117 ± 38%, 100 ± 34%, and 93 ± 21% for 1 minute, 1 day, and 1 week time points, respectively. In preserved latanoprost instilled corneas, SEM showed that only the immediate group exhibited superficial cell damage and a significant decrease in the corneal TER compared to the controls and other time points and to the immediate preservative-free latanoprost corneas. In the preserved latanoprost groups, the relative TER values were 18 ± 5%, 110 ± 28%, and 92 ± 10%, for the three respective observation time points.Conclusions: Preservative-free latanoprost can be safely instilled to the corneal epithelium. Latanoprost with 0.02% BAC has an immediate deleterious impact on the corneal epithelium; however, it disappears within 24 hours after instillation.

Myopia Outcome Study of Atropine in Children (MOSAIC): an investigator-led, double-masked, placebo-controlled, randomised clinical trial protocol

Background: The Myopia Outcome Study of Atropine in Children (MOSAIC) aims to explore the efficacy, safety, acceptability and mechanisms of action of 0.01% unpreserved atropine for myopia control in a European population. Methods: MOSAIC is an investigator-led, double-masked, placebo-controlled, randomised clinical trial (RCT) investigating the efficacy, safety and mechanisms of action of 0.01% atropine for managing progression of myopia. During Phase 1 of the trial, 250 children aged 6-16 years with progressive myopia instil eye drops once nightly in both eyes from randomisation to month 24. From month 24 to 36  participants are re-randomised in Phase 2 of the trial, into continued 0.01% atropine, and washout, at 1:1 ratio for those participants initially randomised to the intervention arm (n=167), during which any potential rebound effects on cessation of treatment will be monitored. All participants initially assigned to the placebo (n=83) crossover to the intervention arm of the study for Phase 2, and from month 24 to 36, instil 0.01% atropine eye drops in both eyes once nightly. Further treatment and monitoring beyond 36 months is planned (Phase 3) and will be designed dependent on the outcomes of Phase 1. Results: The primary outcome measure is cycloplegic spherical equivalent refractive error progression at 24 months. Secondary outcome measures include axial length change as well as the rebound, safety and acceptability profile of 0.01% atropine. Additional analyses will include the mechanisms of action of 0.01% atropine for myopia control. Conclusions: The generalisability of results from previous clinical trials investigating atropine for myopia control is limited by the predominantly Asian ethnicity of previous study populations. MOSAIC is the first RCT to explore the efficacy, safety and mechanisms of action of unpreserved 0.01% atropine in a predominantly White population.

Safety data on in situ gelling bimatoprost loaded nanovesicular formulations

In vitro cytotoxicity and in vivo acute and 7 days repeat-dose ocular toxicity studies, were conducted in rabbits, in accordance with the Organisation for Economic Co-operation and Development (OECD) guidelines, for bimatoprost loaded nanovesicular aqueous dispersion (BMT-NV) and its in-situ gelling sub-conjunctival implant (BMT-NV-IM). For details on the preparation and evaluation of BMT-NV and its BMT-NV-IM for the control of glaucoma, please refer to 'Bimatoprost loaded nanovesicular long-acting sub-conjunctival in-situ gelling implant: In vitro and in vivo evaluation' (Yadav et al., 2019). The in vivo ocular toxicity was performed only after confirming dermal safety, as required by OECD. Histological evaluation of various ocular tissues, following sub-conjunctival implantation with BMT-NV-IM, was done for ocular tolerance studies.

Myopia Outcome Study of Atropine in Children (MOSAIC): an investigator-led, double-masked, placebo-controlled, randomised clinical trial protocol

Background: The Myopia Outcome Study of Atropine in Children (MOSAIC) aims to explore the efficacy, safety, acceptability and mechanisms of action of 0.01% unpreserved atropine for myopia control in a European population.

Methods: MOSAIC is an investigator-led, double-masked, placebo-controlled, randomised clinical trial (RCT) investigating the efficacy, safety and mechanisms of action of 0.01% atropine for managing progression of myopia. During Phase 1 of the trial, 250 children aged 6-16 years with progressive myopia instil eye drops once nightly in both eyes from randomisation to month 24. No treatment is given during Phase 2 from month 24 to 36 (washout period) for those participants initially randomised to the intervention arm (n=167), during which any potential rebound effects on cessation of treatment will be monitored. All participants initially assigned to the placebo (n=83) crossover to the intervention arm of the study for Phase 2, and from month 24 to 36, instil 0.01% atropine eye drops in both eyes once nightly. Further treatment and monitoring beyond 36 months is planned (Phase 3) and will be designed dependent on the outcomes of Phase 1.

Results: The primary outcome measure is cycloplegic spherical equivalent refractive error progression at 24 months. Secondary outcome measures include axial length change as well as the rebound, safety and acceptability profile of 0.01% atropine. Additional analyses will include the mechanisms of action of 0.01% atropine for myopia control.

Conclusions: The generalisability of results from previous clinical trials investigating atropine for myopia control is limited by the predominantly Asian ethnicity of previous study populations. MOSAIC is the first RCT to explore the efficacy, safety and mechanisms of action of unpreserved 0.01% atropine in a predominantly White population.

Trial registration: ISRCTN: ISRCTN36732601 (04/10/2017), EudraCTdatabase 2016-003340-37 (03/07/2018).

An in vivo confocal, prospective, masked, 36 months study on glaucoma patients medically treated with preservative-free or preserved monotherapy

The aim of this study was to evaluate the in vivo effects at 3 years of preservative-free tafluprost on corneal health. It was a prospective, masked, study on consecutive patients with a new prescription of preservative-free (PF) tafluprost (naïve-N or switched-S, 44 and 14 patients), and preserved (P) bimatoprost 0.003% or travoprost 0.004% (P-group, 35 patients). A complete ophthalmic examination and an in vivo corneal confocal microscopy evaluation were performed at baseline and every 6 months for 3 years. Ninety-three patients were enrolled, clinical parameters were similar in the groups at baseline, apart from intraocular pressure (IOP) which was lower in the S-group (p = 0.012). Both at baseline and over time, confocal microscopy parameters had different trends. At baseline, keratocyte activation was similar in the three groups (p = 0.43) but over the next months naïve patients treated with PF-tafluprost presented a significant (p = 0.004) reduction in keratocyte activation. Sub-basal nerves tended to increase in patients switched to PF-tafluprost (p = 0.07) while were stable in the other two groups (p = 0.11 in PF and 0.40 in P group). Grade of tortuosity was stable over time in the three groups. Beading-like formations were stable over time for the P- and the PF-group, while significantly increased in the S-group (p = 0.027). Endothelial density values were statistically different at baseline (p = 0.007), they decreased both in PF-group and in S-group (p = 0.048 and 0.001, respectively), while increased in P-group (p = 0.006). Our study is the first to show that a PF-tafluprost formulation does not significantly alter the corneal structures as examined by confocal microscopy after 36 months of topical daily therapy, while improving corneal alterations due to chronic preserved therapies.

Effects of sustained daily latanoprost application on anterior chamber anatomy and physiology in mice

Latanoprost is a common glaucoma medication. Here, we study longitudinal effects of sustained latanoprost treatment on intraocular pressure (IOP) in C57BL/6J mice, as well as two potential side-effects, changes in iris pigmentation and central corneal thickness (CCT). Male C57BL/6J mice were treated daily for 16 weeks with latanoprost. Control mice were treated on the same schedule with the preservative used with latanoprost, benzalkonium chloride (BAK), or handled, without ocular treatments. IOP and CCT were studied at pre-treatment, 2 "early" time points, and 2 "late" time points; slit-lamp analysis performed at a late time point; and expression of corneal and iridial candidate genes analyzed at the end of the experiment. Latanoprost lowered IOP short, but not long-term. Sustained application of BAK consistently resulted in significant corneal thinning, whereas sustained treatment with latanoprost resulted in smaller and less consistent changes. Neither treatment affected iris pigmentation, corneal matrix metalloprotease expression or iridial pigment-related genes expression. In summary, latanoprost initially lowered IOP in C57BL/6J mice, but became less effective with sustained treatment, likely due to physiological adaptation. These results identify a new resource for studying changes in responsiveness associated with long-term treatment with latanoprost and highlight detrimental effects of commonly used preservative BAK.

Preservatives in glaucoma medication

Preservatives continue to be in widespread use in ophthalmic medications due to the convenience they provide, regulatory requirements and the higher cost of alternatives. Benzalkonium chloride (BAK) remains the most commonly used preservative but there is a trend towards the use of preservative-free (PF) drops for glaucoma, although at a higher price. An extensive body of literature explores BAK toxicity on ocular structures in animal and laboratory studies (in vitro and in vivo). Non-randomised controlled studies have provided some supporting evidence of its toxicity in patients, especially in those with pre-existing ocular surface disease (OSD) or on multiple medications. However, there have been very few randomised controlled trials that compare the same medication with and without BAK preservative. Several of these trials have never been published in any peer reviewed journals. Notwithstanding, those that have been published, have not demonstrated any clear benefits of the BAK-free formulations. Short duration and exclusion of those with OSD are limitations of these studies. There is a lack of evidence of clinically significant harm from a small number of BAK preserved drops in patients without OSD. This means that generally more expensive PF glaucoma medications should only be recommended for those on poly pharmacy or those with OSD but are not necessarily required for all patients.

[Effects of artificial tears on ocular surface in glaucomatous patients with long-term instillation of preserved antiglaucoma eye drops]

PURPOSE

To study the effects of long-term instillation of 0.18% sodium hyaluronate artificial tears VISMED multi on ocular surface in glaucomatous patients with long-term instillation of preserved anti-glaucoma drops.

MATERIAL AND METHODS

The study included 79 patients (40 female and 39 male; 79 eyes in total) with primary open-angle glaucoma (POAG) divided into 3 groups according to disease stage: mild or early (stage I) glaucoma - 15 patients (15 eyes), moderate (stage II) glaucoma - 30 patients (30 eyes), advanced or severe (stage III) glaucoma - 34 patients (34 eyes). Conjunctival and corneal changes were assessed with Norn's test, Schirmer I test and corneal fluorescein staining test. All patients completed Ocular Surface Disease Index (OSDI) questionnaire. Corneal compensated intraocular pressure (IOPcc) was measured using Ocular Response Analyzer (ORA) (Reichert Optics Inc., USA). In addition to hypotensive therapy, all patients received instillations of 0.18% sodium hyaluronate (VISMED multi) three times every day. After 14 days, all examinations were repeated.

RESULTS

The condition of eye surface in patients with moderate and advanced (stage II and III) glaucoma depends on the degree of IOPcc compensation. As glaucoma increases in severity, the pathological changes in the ocular surface progress. Instillations of 0.18% sodium hyaluronate solution lead to significant improvement of the test results in all groups, and in early glaucoma patients it restores all objective indicators to normal values.

CONCLUSION

Treatment with 0.18% sodium hyaluronate solution (VISMED multi) leads to statistically significant (p<0.05) improvement of ocular surface condition in glaucoma patients with long-term instillation of preserved antiglaucoma eye drops.

High Permeability and Intercellular Space Widening With Brimonidine Tartrate Eye Drops in Cultured Stratified Human Corneal Epithelial Sheets

PURPOSE

To investigate the toxicity of topical glaucoma medications using cultured stratified human corneal epithelial sheets (HCES).

METHODS

HCES were exposed for 30 minutes to the following glaucoma medications: 0.1% brimonidine with sodium chlorite as the preservative, 0.005% latanoprost with 0.02% benzalkonium chloride (BAC) as the preservative, and 0.5% timolol with 0.005% BAC as the preservative. Then, cell viability and barrier function were tested by the WST-1 assay and carboxyfluorescein permeability assay, respectively. After exposure to glaucoma medications, HCES were evaluated by hematoxylin and eosin staining, periodic acid-Schiff staining, scanning electron microscopy, and transmission electron microscopy.

RESULTS

HCES exposed to brimonidine showed higher viability and better preservation of cell morphology and microvilli compared with cell sheets exposed to latanoprost or timolol. The carboxyfluorescein permeability assay demonstrated that the barrier function was preserved after HCES were exposed to timolol, but not after exposure to brimonidine or latanoprost. Transmission electron microscopy revealed widening of intercellular junctions with prominent deposits of glycogen or mucopolysaccharide (periodic acid-Schiff positive) after exposure of HCES to brimonidine.

CONCLUSIONS

The toxicity of 0.1% brimonidine containing sodium chlorite for HCES was lower than that of ophthalmic preparations containing BAC. Reduction of the barrier function occurred after HCES were exposed to brimonidine because of widening of intercellular junctions.

Ocular Surface Disease in Patients under Topical Treatment for Glaucoma

Purpose

To examine the relationship between ocular surface disease (OSD) and topical antiglaucoma therapy.

Methods

A total of 211 eyes of 211 patients with open-angle glaucoma or ocular hypertension on topical medication were recruited over 10 months. Controls were 51 eyes of 51 healthy age- and sex-matched volunteers. In each patient, we recorded the intraocular pressure-lowering eyedrops used, the number of medications used, and daily and cumulative preservative concentrations (PC). Main outcome measures were fluorescein corneal staining score (Oxford scale), lower tear meniscus height (LTMH) (spectral-domain optical coherence tomography), noninvasive tear film breakup time (NI-TBUT) (Oculus Keratograph 5M), and OSD symptom questionnaire index (OSDI).

Results

Compared to controls, significantly higher OSDI (median [interquartile range] 10.24 [4.54-18.94] vs 2.5 [0-12.5]; p<0.001) and corneal staining (≥1: 64.93% vs 32.61%; p<0.001) scores were recorded in the medication group. The NI-TBUT and LTMH failed to vary between the groups (p>0.05). A higher daily PC was associated with a lower LTMH (R −0.142; p = 0.043). In the medication group, multivariate analysis identified correlations between benzalkonium chloride (BAK) (odds ratio [OR] 1.56) and BAK plus polyquaternium-containing drops (OR 5.09) or higher OSDI (OR 1.06) and abnormal corneal staining test results and between older age (mean ratio [MR] 1.05), longer treatment duration (MR 1.02), or corneal staining presence (MR 1.22) and a higher OSDI score.

Conclusions

Ocular surface disease was more prevalent in the medication group. The main factors impacting OSD were drops with preservatives, longer treatment duration, and older age.

Pharmacokinetics, Efficacy, and Safety of the Preservative-free Fixed Combination of Tafluprost 0.0015% and Timolol 0.5% in Healthy Volunteers: A Phase I Comparison vs. the Corresponding Preservative-free Monotherapies

PURPOSE

Plasma concentrations of tafluprost acid and timolol were compared after single (Day 1) and repeated (Day 8) instillations of once-daily tafluprost 0.0015%-timolol 0.5% preservative-free (PF) fixed-dose combination (FDC), once-daily PF tafluprost 0.0015%, and twice-daily PF timolol 0.5%.

PATIENTS AND METHODS

Fifteen healthy volunteers were randomized to this double-masked, single-center, three-period cross-over study. A wash-out interval of at least 4 weeks separated each three 8-day dosing period. Blood samples were drawn on the first and last day of each dosing period, prior to the morning dose, as well as 5, 10, 15, 30, and 45 min, and 1, 1.5, 2, 4, 8, and 12 h post-dosing. Sample plasma concentrations of tafluprost acid and/or timolol were determined and maximum concentration (C max), area under the concentration-over-time curve from time zero to the last time point with a quantifiable measurement (AUC0-last), and time to maximum concentration were calculated. Intraocular pressure (IOP), adverse events, and ocular/systemic safety variables were also evaluated.

RESULTS

Plasma concentrations of tafluprost acid were low, with similar levels measured subsequent to either single or repeated dosing of PF FDC and PF tafluprost. On both sampling days, concentrations peaked at 10 min after the dose, and were cleared from the blood circulation by 30 min; average C max ranged from 17 to 24 pg/mL, and AUC0-last from 3 to 5 pg*h/mL. Plasma concentrations of timolol were comparable after the first dose of PF FDC or PF timolol. Concentrations peaked at 15 min post-dose and diminished in a similar manner after 2 h; average C max was 800 pg/mL and AUC0-last 3900 pg*h/mL. As expected, PF timolol produced a higher Day 8 pre-dose timolol concentration than PF FDC (235 vs. 37 pg/mL; p < 0.001, respectively). The Day 8 post-dose changes in timolol concentrations were relative to this pre-dose difference. All study treatments were well tolerated and safe. PF FDC seemed to provide the best IOP reduction.

CONCLUSIONS

PF FDC demonstrated good IOP-lowering efficacy and displayed similar pharmacokinetic characteristics to the monotherapy agents. Exposure to timolol was reduced via the halved dosing.

In vitro and in vivo corneal effects of latanoprost combined with brimonidine, timolol, dorzolamide, or brinzolamide

To examine the relevance of concentration of benzalkonium chloride (BAK) on the cornea, we investigated the effects of latanoprost containing BAK alone and in combination with other antiglaucoma drug classes on corneal epithelium in vitro in a cultured rabbit corneal cell line (SIRC) and in vivo, using a corneal resistance device (CRD). [In vitro] staten's seruminstitut rabbit corneal cells were exposed to 0.005% latanoprost for 30s, followed by either phosphate buffered saline (control), 0.1% brimonidine, 0.5% timolol, 1% dorzolamide, or 1% brinzolamide. The number of viable cells was counted at 8, 15, and 30min. [In vivo] Albino rabbits were administered one drop of 0.005% latanoprost, followed 5min later by one drop of an agent from the in vitro trial. This was repeated every 15min for a total of three times. The change in corneal barrier function was assessed by measuring the corneal resistance at 2 and 30min after the final administration. [In vitro] At 8min, the viable cell count in the latanoprost+dorzolamide group was significantly lower than in the control group. At 15 and 30min, all treatment groups, except the latanoprost+brimonidine group, demonstrated significantly lower viable cell counts than the control group. [In vivo] At 2min after the final eye drop, the latanoprost+timolol group and the latanoprost+brinzolamide group demonstrated significantly lower corneal resistance than did the latanoprost+brimonidine group. No significant difference was observed between the agents at 30min. In conclusion, when combining latanoprost containing benzalkonium chloride with other classes of antiglaucoma drugs, brimonidine may cause the least corneal damage, and the number of drug administrations may be an important factor.

Preparation and optimisation of anionic liposomes for delivery of small peptides and cDNA to human corneal epithelial cells

Drug delivery to corneal epithelial cells is challenging due to the intrinsic mechanisms that protect the eye. Here, we report a novel liposomal formulation to encapsulate and deliver a short sequence peptide into human corneal epithelial cells (hTCEpi). Using a mixture of Phosphatidylcholine/Caproylamine/Dioleoylphosphatidylethanolamine (PC/CAP/DOPE), we encapsulated a fluorescent peptide, resulting in anionic liposomes with an average size of 138.8 ± 34 nm and a charge of -18.2 ± 1.3 mV. After 2 h incubation with the peptide-encapsulated liposomes, 66% of corneal epithelial (hTCEpi) cells internalised the FITC-labelled peptide, demonstrating the ability of this formulation to effectively deliver peptide to hTCEpi cells. Additionally, lipoplexes (liposomes complexed with plasmid DNA) were also able to transfect hTCEpi cells, albeit at a modest level (8% of the cells). Here, we describe this novel anionic liposomal formulation intended to enhance the delivery of small cargo molecules in situ.

Acute cytotoxic effects of marketed ophthalmic formulations on human corneal epithelial cells

The purpose of the study was to devise a fast, reliable and sensitive cell viability assay for assessment of acute cytotoxicity on human corneal epithelial cells by using a clinically relevant exposure time. Acute cytotoxic effects of the pharmaceutical excipients benzalkonium chloride (BAC), macrogolglycerol hydroxystearate (MGHS40), polysorbate 80 (PS80) and marketed ophthalmic formulations (Lumigan(®), Monoprost(®), Taflotan(®), Travatan(®), Xalatan(®)) containing these excipients were tested. Human corneal epithelial cell (HCE-T) viability was assessed by measuring the reduction of resazurin to highly fluorescent resorufin. Expression of the tight junction proteins in HCE-T cells were characterized by immunofluorescence staining. Presence of tight junction proteins in HCE-T cells was demonstrated. BAC preserved ophthalmic formulations showed concentration-dependent and time-dependent cytotoxicity to human corneal epithelium. In contrast, no acute cytotoxicity of non-ionic stabilizing/solubilizing excipients (MGSH40 and PS80) or ophthalmic formulation containing these excipients was observed. Marketed ophthalmic formulations used for glaucoma medication show differential toxicity on human corneal epithelial cells. The present study revealed that BAC-preserved ophthalmic formulations were able to induce acute cytotoxic effects even during a clinically relevant exposure time, which was not observed with MGSH40 and PS80 excipients or ophthalmic formulations containing these excipients.

Long-term topical application of preservative-free prostaglandin analogues evokes macrophage infiltration in the ocular adnexa

Success of the long-term glaucoma therapy and preservation of the visual function strongly depend on patients' compliance which may be affected by the inconvenience of treatment and its side effects. Recently, introduction of preservative-free anti-glaucoma agents has become an important step towards improved glaucoma care by eliminating the negative effects of preservatives on the eye surface. Although, newly developed eye drop formulations do not contain standard preservatives, they still can be harmful to ocular surface due to other excipients. In this study, we compared tolerability of commercial preservative-free (pf) prostaglandin analogues (pf tafluprost, pf latanoprost and pf bimatoprost) in long-term topical application in rabbits in vivo. We found that after eight weeks treatment, pf latanoprost was the worst tolerated among the tested drops. It expressed increased conjunctival redness and blinking frequency. Furthermore, it caused increased LDH release in the aqueous humour, infiltration of macrophages in the eyelids and visible defects in conjunctival goblet cells. However, we did not detect increased levels of inflammatory markers in the tear fluid or in the aqueous humour. Based on our study, we suspect that these negative effects are related to excipients included in pf latanoprost formulation.

Ocular Tolerability of Preservative-Free Tafluprost and Latanoprost: in vitro and in vivo Comparative Study

Objective:

Detrimental effects of the preserved prostaglandin analogs (PGAs) have been thoroughly documented in the published literature. The current work studied two preservative-free (PF) prostaglandin eye drops: PF tafluprost and PF latanoprost. The aim of the study was to compare these two PF formulations in vitro for viability of the human corneal epithelial (HCE-T) cells and in vivo for ocular tolerability of the rabbit eye.

Method:

Viability of the HCE-T cells was measured by the MTS assay. The SV40-immortalized HCE-T cells were exposed to 100 µL of the drug solutions (at their commercial concentrations) or the culture medium. Ocular irritation was evaluated after repeated instillation of the drug solutions in Japanese white rabbits (Kbl:JW).

Results:

A significant loss of HCE-T cell viability was observed in vitro immediately after the exposure to PF latanoprost formulation but not immediately after the exposure to PF tafluprost formulation. Congruently, PF latanoprost induced in vivo more irritation on the rabbit eye than PF tafluprost.

Conclusion:

Comparing these two PF formulations in vitro and in vivo, it is considered that ocular tolerability of PF tafluprost is better than PF latanoprost. Taking into account the composition of these two PF PGA formulations, the solubilizing agent macrogolglycerol hydroxystearate 40 (MGHS40) contained in PF latanoprost formulation is a plausible cause for the negative effects.

Effect of preservative removal from fixed-combination bimatoprost/timolol on intraocular pressure lowering: a potential timolol dose-response phenomenon

PURPOSE

Many patients with glaucoma require combination therapies to achieve target intraocular pressure (IOP) and preserve visual function. Ocular hypotensives often contain a preservative (eg, benzalkonium chloride [BAK]), but preservative-free (PF) formulations have been developed for patients with sensitivity. A Phase III study found the efficacy of bimatoprost 0.03%/timolol 0.5% (bim/tim, Ganfort(®)) PF to be equivalent to that of preserved bim/tim, although a trend favoring bim/tim PF was observed. As BAK is a corneal penetration enhancer, this literature review aims to explain these findings by exploring the relationship between timolol concentration and its IOP-lowering effect.

METHODS

Systematic searches were performed in Scopus and PubMed for clinical trials published in English between 1960 and July 2014 using the keywords "timolol", "intraocular pressure", and the concentrations "1%, 0.5%, OR 0.25%". Articles that directly compared IOP-lowering effects of ≥2 concentrations of timolol were identified by manual screening, and cross-checked for duplication.

RESULTS

Seventeen studies that included 10-371 patients were evaluated; the majority were randomized (16/17), double-masked (14/17), and enrolled patients with open-angle glaucoma or ocular hypertension (12/17). All studies investigated timolol in preserved formulations. Timolol concentrations tested ranged from 0.008% to 1.5%. Of 13 studies comparing timolol 0.25% versus 0.5%, two found the 0.25% dose to have greater IOP-lowering effects, and three reported the opposite; eight reported similar IOP lowering. Results also indicate that timolol 0.5% may be more effective than higher concentrations.

CONCLUSION

The evidence suggests that timolol may have an inverted U-shaped dose-response curve, and that its optimal IOP-lowering concentration is between 0.25% and 0.5%. Compared with bim/tim, removal of the permeability enhancer BAK in bim/tim PF could have resulted in a lower timolol concentration at the target site, bringing the effective concentration within the 0.25%-0.5% range and enhancing the efficacy of bim/tim PF.

Effects of Four Formulations of Prostaglandin Analogs on Eye Surface Cells. A Comparative Study

We evaluated the cytotoxic effects of four prostaglandin analogs (PGAs) used to treat glaucoma. First we established primary cultures of conjunctival stromal cells from healthy donors. Then cell cultures were incubated with different concentrations (0, 0.1, 1, 5, 25, 50 and 100%) of commercial formulations of bimatoprost, tafluprost, travoprost and latanoprost for increasing periods (5 and 30 min, 1 h, 6 h and 24 h) and cell survival was assessed with three different methods: WST-1, MTT and calcein/AM-ethidium homodimer-1 assays. Our results showed that all PGAs were associated with a certain level of cell damage, which correlated significantly with the concentration of PGA used, and to a lesser extent with culture time. Tafluprost tended to be less toxic than bimatoprost, travoprost and latanoprost after all culture periods. The results for WST-1, MTT and calcein/AM-ethidium homodimer-1 correlated closely. When the average lethal dose 50 was calculated, we found that the most cytotoxic drug was latanoprost, whereas tafluprost was the most sparing of the ocular surface in vitro. These results indicate the need to design novel PGAs with high effectiveness but free from the cytotoxic effects that we found, or at least to obtain drugs that are functional at low dosages. The fact that the commercial formulation of tafluprost used in this work was preservative-free may support the current tendency to eliminate preservatives from eye drops for clinical use.

Latanoprost in the treatment of glaucoma

Prostaglandins are approved by the European Glaucoma Society guidelines as first-line treatment for glaucoma. This review focuses on latanoprost, an ester prodrug of prostaglandin (PG) F_2α, which was the first of the currently available topical PGF_2α analogs to be launched for glaucoma or ocular hypertension and which still accounts for the majority of prescriptions. It is better absorbed than the parent compound through the cornea, and peak concentration of the active drug is in the aqueous humor 1–2 hours after topical dosing (15–30 ng/mL). Metabolism occurs mainly in the liver. Latanoprost (0.005%) has been very well studied in clinical trials and meta-analyses that show it to be generally as effective as the other PG analogs (bimatoprost, travoprost, and tafluprost) and more effective than timolol, dorzolamide, and brimonidine. Latanoprost has good short- and long-term safety and tolerability profiles. In common with other prostaglandins, it lacks systemic effects, but can cause ocular adverse events such as conjunctival hyperemia, pigmentation of the iris, periocular skin or eyelashes, hypertrichosis, and ocular surface effects or irritation. Latanoprost is significantly better tolerated than either bimatoprost or travoprost. Patients treated with latanoprost have better compliance and persist with therapy longer than those that are given other drugs. An improved formulation of latanoprost without the preservative benzalkonium chloride has recently been developed. It is as effective as conventional latanoprost, has a lower incidence of hyperemia, and can be stored at room temperature. In conclusion, latanoprost has the best efficacy–tolerability ratio of the PG analogs available for glaucoma treatment, and has good compliance and persistence. These factors should be improved further by the recent development of preservative-free latanoprost.

Mechanisms of benzalkonium chloride toxicity in a human trabecular meshwork cell line and the protective role of preservative-free tafluprost

BACKGROUND

Benzalkonium chloride (BAK) is a controversial ophthalmic preservative because of its prominent side-effect profile. In this study, we examined the mechanism of BAK toxicity in human trabecular meshwork cells (HTMC) and compared the effects of BAK with tafluprost free acid, which is an active form of tafluprost commercially available in a preservative-free formulation.

METHODS

Primary HTMC were treated with different BAK concentrations over various exposure times. Cell viability was quantified using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenol tetrazolium bromide assay, and apoptosis was measured by enzyme-linked immunosorbent assay. The cell viability of primary HTMC exposed to various concentrations and times of tafluprost free acid was also determined. Cells were treated with BAK and tafluprost free acid for 30 min at 37°C, and cell viability was again assessed. The effect of BAK on the gap junction protein Connexin-43 (Cx43) expression was subsequently examined.

RESULTS

BAK treatment resulted in a dose- and time-dependent decline in cell viability. Apoptosis increased following BAK treatment. Tafluprost-free acid treatment did not significantly affect cell viability. Tafluprost co-treatment with BAK resulted in an increase in cell viability as compared with BAK treatment alone. BAK treatment upregulated Cx43 expression in HTMC.

CONCLUSIONS

These results demonstrate that BAK is harmful to the health of cultured HTMC. Tafluprost is both safe and cytoprotective against BAK for these HTMC. The effect of tafluprost on the gap junctions of the HTM should be further investigated.

In vitro effects of preserved and unpreserved anti-allergic drugs on human corneal epithelial cells

PURPOSE

Treatment with topical eye drops for long-standing ocular diseases like allergy can induce detrimental side effects. The purpose of this study was to investigate in vitro cytotoxicity of commercially preserved and unpreserved anti-allergic eye drops on the viability and barrier function of monolayer and stratified human corneal-limbal epithelial cells.

METHODS

Cells were treated with unpreserved ketotifen solution, benzalkonium chloride (BAC)-containing anti-allergic drugs (ketotifen, olopatadine, levocabastine) as well as BAC alone. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to determine cell viability. Effects of compounds on barrier function were analyzed measuring transepithelial electrical resistance (TEER) to determine paracellular permeability and rose bengal assays to evaluate transcellular barrier formation.

RESULTS

The BAC-preserved anti-allergic formulations and BAC alone significantly reduced cell viability, monolayer cultures being more sensitive to damage by these solutions. Unpreserved ketotifen induced the least diminution in cell viability. The extent of decrease of cell viability was clearly dependent of BAC presence, but it was also affected by the different types of drugs when the concentration of BAC was low and the short time of exposure. Treatment with BAC-containing anti-allergic drugs and BAC alone resulted in increased paracellular permeability and loss of transcellular barrier function as indicated by TEER measurement and rose bengal assays.

CONCLUSIONS

The presence of the preservative BAC in anti-allergic eye drop formulations contributes importantly to the cytotoxic effects induced by these compounds. Stratified cell cultures seem to be a more relevant model for toxicity evaluation induced on the ocular surface epithelia than monolayer cultures.

Comparison of corneal safety and intraocular pressure-lowering effect of tafluprost ophthalmic solution with other prostaglandin ophthalmic solutions

PURPOSE

The benzalkonium chloride (BAK) content of tafluprost ophthalmic solution (Tapros(®): tafluprost) has been reduced to balance corneal safety and preservative effectiveness (old formulation: 0.01%; new formulation: 0.001%). However, no reports have been published on its clinical effect. Therefore, we conducted a clinical research study to compare the safety of BAK-reduced tafluprost on the ocular surface with other prostaglandin ophthalmic solutions.

METHODS

This clinical study included 28 glaucoma patients (28 eyes) with a treatment history of latanoprost ophthalmic solution (Xalatan(®)) or travoprost ophthalmic solution (Travatan Z(®)), who presented with corneal epithelial disorders. The subjects were switched to BAK-reduced tafluprost, and its effect on the ocular surface was examined after 1 and 2 months of treatment [using fluorescein staining score, hyperemia, tear film breakup time, and intraocular pressure (IOP) lowering].

RESULTS

In all analyzed subjects (N=27), the fluorescein staining score was significantly improved after switching to BAK-reduced tafluprost (P<0.0001). Conversely, the IOP-lowering effect was not notably changed. The subjects switched from latanoprost (n=10) showed significant improvement in fluorescein staining score (P<0.05) as well as in IOP lowering (P<0.01). The subjects switched from travoprost (n=17) also showed significant improvement in fluorescein staining score (P<0.001), but without a significant change in IOP lowering.

CONCLUSIONS

Tafluprost with reduced BAK has potential as a superior antiglaucoma drug, not only for its IOP-lowering effect, but also for its good corneal safety profile.

Ocular surface cytotoxicity and safety evaluation of tafluprost, a recently developed anti-glaucoma prostaglandin analog

In vitro cytotoxicity of tafluprost, which is the most recently developed anti-glaucoma prostaglandin (PG) analog, in ocular surface cells is addressed in comparison with other PG analogs. Irrespective of cell lines and models, the cytotoxicity of anti-glaucoma PG eyedrops was primarily related to the concentration of benzalkonium chloride (BAK) contained in the eyedrops as a preservative. Accordingly, preservative-free tafluprost was apparently less cytotoxic than BAK-preserved PG analogs. Furthermore, our study for cytotoxicity assays on ocular cells, conducted by comprehensive investigations covering a variety of concentrations and treatment times, which is termed the cell viability score (CVS) system, demonstrated that 0.001% BAK-preserved tafluprost was not cytotoxic, and suggested that tafluprost may even reduce the cytotoxic effect of BAK. It has been reported that adverse reactions associated with tafluprost in healthy human volunteers and patients with glaucoma include conjunctival hyperemia, eyelid pigmentation, eyelash bristles, and deepening of upper eyelid sulcus. Nonetheless, most clinical studies have demonstrated that not only preservative-free tafluprost but also BAK-preserved tafluprost is well tolerated and safe in patients with glaucoma and ocular hypertension.

Ocular toxicity of benzalkonium chloride homologs compared with their mixtures

This study was performed to assess the in vivo ocular toxicity of benzalkonium chloride (BAK) homologs compared with commercially available BAK (BAK mixture) and to assess the ocular toxicity of BAK homolog after repeated ocular application. Rabbit eyes were examined by ophthalmology and scanning electron microscopy (SEM) after 10 applications of BAK homologs with C12 (C12-BAK) and C14 (C14-BAK) alkyl chain lengths and a BAK mixture at concentrations of 0.001% (w/v), 0.003% (w/v), 0.005% (w/v), 0.01% (w/v) and 0.03% (w/v). The ocular toxicity of C12-BAK to rabbit eyes was examined by ophthalmology and histopathology after repeated ocular application for 39 weeks. In addition, the antimicrobial activities of C12-BAK and C14-BAK against A. niger, S. aureus and P. aeruginosa were assessed. Ocular toxicity of C12-BAK was less than those of the BAK mixture and C14-BAK. No ocular toxicity was noted after ocular application of 0.01% C12-BAK to rabbits for 39 weeks. C12-BAK showed antimicrobial activities at a concentration of 0.003%. These results suggest that the use of C12-BAK to replace BAK mixture as a preservative in ophthalmic solutions should be considered in order to reduce the incidence of the corneal epithelial cell injury induced clinically by BAK.

Cationorm shows good tolerability on human HCE-2 corneal epithelial cell cultures

Preservatives have been for a long time known to cause detrimental effects on ocular surface. Cationorm, a preservative-free compound with electrostatic properties is a novel way to solve the problems encountered with traditional benzalkonium chloride (BAK)-containing eye drops. The aim of this study was to evaluate tolerability of the preservative-free cationic emulsion Cationorm in vitro on corneal epithelial cells. The human corneal epithelial cell (HCE-2) culture line was used to study cellular morphology, cytotoxicity and inflammatory responses after Cationorm diluted 1/10 exposure for 5, 15 and 30 min. Exposures to Systane diluted 1/10 with polyquaternium-1/polidronium chloride 0.001% as preservative, BAK 0.001% or C16 (0.0002%) and normal cell culture medium served as positive and negative references. Cell viability was determined by measuring the release of lactate dehydrogenase (LDH) and mitochondrial dehydrogenase activity was evaluated using 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The possible induction of apoptosis was analyzed by measuring the activity of caspase-3, and Cell Counting Kit-8 (CCK-8) was used to evaluate the number of viable cells after the exposure to test compounds. Furthermore, the tendency of the test compounds to produce inflammatory reaction was determined by analyzing the production of proinflammatory cytokines IL-6 and IL-8, and DNA binding of the p65 subunit of transcription factor NF-κB was measured from cell lysates. HCE-2 cells showed no morphological changes after the exposure to Cationorm, but in cells exposed to BAK, clear cytoplasm vacuolization and loose cell-cell contacts were observed in transmission (TEM) or scanning (SEM) electron microscopic analyses. Cell viability, as measured with the release of LDH, indicated a time dependent increase in LDH expression after exposure to all test compounds but especially with BAK. Moreover, Cationorm and BAK time-dependently decreased the mitochondrial metabolism to 73% with Cationorm and 53% with BAK from that of the control cells after 30 min exposure in MTT assay. BAK was the only test compound having clear adverse effects on the cell number and metabolism in CCK-8 assay. The activity of caspase-3 did not show significant differences between the groups. Inflammatory response after exposure to Cationorm was significantly lower than after exposure to BAK. There were no significant differences in NF-κB activity between the groups. Diluted Cationorm and Systane with polyquaternium-1/polidronium chloride 0.001% showed good tolerability on HCE-2 cells and thereby provide a clear improvement when compared to BAK-containing eye drop formulations.

Loteprednol etabonate ophthalmic gel 0.5% following cataract surgery: integrated analysis of two clinical studies

INTRODUCTION

We aimed to evaluate the safety and efficacy of loteprednol etabonate (LE) gel 0.5% compared with vehicle in the treatment of postoperative inflammation and pain following cataract surgery, using the integrated analysis of data from two identical, prospective, multicenter, randomized, double-masked, parallel-group, vehicle-controlled trials.

METHODS

Patients with anterior chamber cell (ACC) inflammation ≥ grade 2 (6-15 cells) 1 day post-surgery were randomized to receive 1 or 2 drops of LE gel 0.5% or vehicle 4 times per day instilled in the study eye for 14 days. Primary outcome measures included the proportion of patients with complete resolution of ACC and grade 0 (no) pain on postoperative Day 8. Safety endpoints included adverse events (AEs), changes from baseline in intraocular pressure (IOP) and visual acuity (VA), biomicroscopy, and funduscopy findings. Gel comfort was graded by patients according to drop sensation.

RESULTS

The intent-to-treat population included 813 patients (409 LE gel 0.5% and 404 vehicle). At postoperative Day 8, 30.8% and 15.1% of patients randomized to LE gel 0.5% or vehicle, respectively, had complete resolution of ACC, while 74.3% and 43.8% of patients, respectively, had grade 0 pain (P < 0.001 for both). Tolerability assessments for ocular itching, photophobia, and tearing favored LE gel 0.5% compared with vehicle at different time points beginning at Day 3. Two patients in the LE gel 0.5% group and 1 patient in the vehicle group exhibited a transient treatment-emergent increase in IOP ≥ 10 mmHg. Treatment-related AEs were generally mild to moderate and occurred less frequently with LE gel 0.5% than with vehicle. Reports of treatment-related blurred vision were rare (n = 2, vehicle).

CONCLUSION

LE gel 0.5% was efficacious and well tolerated in the treatment of postoperative pain and inflammation following ocular surgery, with minimal risk of IOP elevation.

Effect of preservative-free tafluprost on keratocytes, sub-basal nerves, and endothelium: a single-blind one-year confocal study on naïve or treated glaucoma and hypertensive patients versus a control group

PURPOSE

To record the impact of preservative-free Tafluprost on corneal status examined by in vivo confocal microscopy.

METHODS

A prospective cohort study on consecutive naïve or previously treated patients with a new prescription of preservative-free Tafluprost. All subjects underwent a complete ophthalmic examination [comprehensive of intraocular pressure (IOP) and central corneal thickness (CCT) measurements], and an in vivo corneal confocal microscopy evaluation, at baseline and 12 months later. A healthy control group was selected and examined at the same time.

RESULTS

Seventy-five subjects (16 controls, 20 naïve, and 39 treated) were enrolled. At baseline, IOP was 16 (13.8-18.6), 21.5 (18-23.7), and 18 (16-22) mmHg, (P=0.01); and CCT did not differ among the groups (P=0.25). Epithelial cells, keratocyte activation, a number of sub-basal nerves, and the grade of nerve tortuosity were similar (P=0.233, 0.11, 0.417, and 0.05, respectively), in naïve and controls, while previously treated patients had significantly less epithelial cells and sub-basal corneal nerves (P<0.0001), keratocyte activation, increased number of bead-like formations, and nerve tortuosity (P<0.0001). At month 12, IOP decreased in both patient groups (P<0.001); CCT did not change. Previously treated patients showed an improvement in confocal parameters: increased epithelial cells (P=0.0006), reduced keratocyte activation (P=0.003), increased number of corneal nerves (P=0.0004), decreased number of bead-like formations (P=0.0013), and nerve tortuosity (P=0.0008). Naïve patients did not show significant changes.

CONCLUSION

The study confirmed the efficacy of preservative-free Tafluprost in reducing IOP, and underlined the drug's safety in naïve glaucoma patients with regard to corneal status. In the balance between efficacy and tolerability, formulations with low cytotoxicity may ensure fewer side effects, with higher tolerability and better compliance.

Ocular pharmacokinetics of bimatoprost formulated in DuraSite compared to bimatoprost 0.03% ophthalmic solution in pigmented rabbit eyes

PURPOSE

To compare the aqueous humor (AH) and iris-ciliary body (ICB) concentration of bimatoprost in rabbit eyes treated with ISV-215 (0.03% bimatoprost formulated in DuraSite) with the marketed product bimatoprost 0.03% ophthalmic solution.

METHODS

The left eye of rabbits received a single topical instillation of either ISV-215 (n = 32 eyes) or bimatoprost 0.03% (n = 32 eyes). At predetermined time points, levels of bimatoprost and bimatoprost acid in the AH and the ICB were quantified by HPLC-MS/MS.

RESULTS

Both bimatoprost and bimatoprost acid were detected in the AH and the ICB within 15 minutes of dosing. Bimatoprost acid concentrations in both compartments were markedly higher than bimatoprost. There was a statistically significant (P < 0.01) increase in the concentration of the prodrug in the AH and its acid form in the ICB in animals treated with ISV-215 compared to bimatoprost 0.03%. In the ISV-215-treated rabbit eyes, the highest concentrations of bimatoprost and bimatoprost acid were in the ICB and AH, respectively, while in the bimatoprost 0.03%-treated eyes, no differences in the drug content of the selected ocular tissues were observed.

CONCLUSIONS

Bimatoprost 0.03% formulated in DuraSite has superior ocular distribution and area under the curve compared to bimatoprost 0.03% in rabbit eyes. This improvement in the pharmacokinetic parameters of ISV-215 may provide us with a better platform to optimize a bimatoprost formulation that offers the same degree of efficacy in lowering intraocular pressure and improved therapeutic index in glaucomatous patients by lessening the ocular side effects associated with long-term use of topical prostaglandin F2α analogs.

Glaucoma therapy and ocular surface disease: current literature and recommendations

PURPOSE OF REVIEW

To provide an update on clinical and experimental literature for ocular surface effects of glaucoma therapy and to provide practical guidelines for ophthalmologists treating glaucoma patients with ocular surface disease (OSD).

RECENT FINDINGS

Preservatives, notably benzalkonium chloride (BAK), continue to contribute to OSD and demonstrate a variety of toxic ocular effects both in-vitro, and in animal/human studies. Recent literature frequently compares BAK with Polyquad, SofZia, and preservative-free therapies. Some clinical benefit has been demonstrated with newer BAK-free alternatives.

SUMMARY

BAK-free and preservative-free therapies are becoming available but are not always a feasible alternative. It is important to recognize different clinical manifestations of allergy and chronic inflammation and to discuss options for patients experiencing OSD.

Tafluprost once daily for treatment of elevated intraocular pressure in patients with open-angle glaucoma

Glaucoma is a leading cause of visual loss worldwide. Current antiglaucoma therapy focuses on lowering intraocular pressure to a safe level. In recent years, prostaglandin analogs have become the first-line agents for treating open angle glaucoma. Tafluprost, which was first reported in 2003, is a novel prostaglandin analog, and has been shown to be a potent ocular hypotensive agent in a number of preclinical and clinical studies. Also, its unique preservative-free formulation helps to decrease preservative-associated ocular disorders and improve patient compliance. In this review, studies from 2003 to 2012 focusing on the structure, metabolism, efficacy, and safety of tafluprost are summarized. These studies suggested that application of tafluprost once daily is a safe and effective treatment for patients with open angle glaucoma.

Tafluprost: The First Preservative-Free Prostaglandin to Treat Open-Angle Glaucoma and Ocular Hypertension

OBJECTIVE:

To review the pharmacology, pharmacokinetics, clinical trial data, efficacy data, and adverse effect incidence of tafluprost.

DATA SOURCES:

A literature search was completed using PubMed, Web of Science, and Google Scholar. Tafluprost was the primary search term. Articles published between January 2008 and April 2012 were included in this review. Additional limits placed on the searches were “human” and “English.” Citations in which tafluprost appeared in the title were 36, 29, and more than 300 in PubMed, Web of Science, and Google Scholar, respectively.

STUDY SELECTION AND DATA EXTRACTION:

Three clinical trials were included in this review. One trial enrolled more than 500 subjects in a randomized fashion. Another also enrolled more than 500 subjects, although the study design was not randomized. The third trial evaluated the effects of tafluprost on subjects who had recently discontinued use of latanoprost, another prostaglandin that is approved to treat glaucoma and ocular hypertension. The duration of all 3 trials was 12 weeks.

DATA SYNTHESIS:

Tafluprost 0.0015% is the first topical prostaglandin approved by the Food and Drug Administration for treatment of open-angle glaucoma and ocular hypertension that does not contain the widely used preservative, benzalkonium chloride (BAK). Although some controversy surrounds the long-term safety of exposure to BAK, clinical trial data are inconclusive. Tafluprost, like other prostaglandin analogues, exerts its effects on prostaglandin F receptors to reduce intraocular pressure (IOP). Results from 1 trial demonstrated significant reductions in IOP when monotherapy was switched to tafluprost monotherapy. Reductions in IOP with tafluprost use were compared with those seen with use of timolol and latanoprost in 2 trials, and noninferiority was observed. Significant reductions in tear osmolarity were noted in subjects who changed from latanoprost, another prostaglandin analogue, to tafluprost therapy. Conjunctival hyperemia is the most common adverse effect seen in patients receiving drugs from this class. Many have also reported stinging, ocular pruritus, increased darkening or growth of eyelashes, and darkening of eyelids, as well as irreversible brown pigmentation of the iris.

CONCLUSIONS:

Clinical trial data suggest that tafluprost is as efficacious as other agents used in the management of ocular hypertension and glaucoma. Its use may be especially advantageous in people with allergies, sensitivities to preservatives, or dry or sensitive eyes.

Corneal epithelial cell viability following exposure to ophthalmic solutions containing preservatives and/or antihypertensive agents

INTRODUCTION

This in-vitro study compared the toxicity of bimatoprost 0.01% containing benzalkonium chloride (BAK) 0.02% with other commercial BAK-free or BAK-containing prostaglandin analogs.

METHODS

Six test solutions were evaluated: travoprost 0.004% with polyquaternium-1 0.001% (PQ), PQ, bimatoprost 0.01% with BAK 0.02%, latanoprost 0.005% with BAK 0.02%, tafluprost 0.0015% preservative free (PF), and BAK 0.02%. Phosphate-buffered saline (PBS) was the live control and 70% methanol was the dead control. Confluent human corneal epithelial cells were incubated with test solutions (diluted 1:5 or 1:10 with PBS) or control solutions for 10 or 25 min, after which cells were fluorescently labeled to distinguish live and dead cells. Data were expressed as a percentage of PBS live-cell fluorescence for automated readouts. Live and dead cells were manually counted for numeric analyses.

RESULTS

For 1:5 and 1:10 dilutions using automated readout, cells exposed to bimatoprost with BAK, latanoprost with BAK, and BAK alone demonstrated significant reductions in the live cell signal compared with PBS, travoprost with PQ, and PQ alone (all P < 0.001). They also demonstrated significantly greater toxicity than tafluprost PF for 1:5 dilutions (all P < 0.001) and 1:10 dilutions (P ≤ 0.02), except for 1:10-diluted bimatoprost with BAK (P = 0.41). For 1:5 dilutions using manual cell count, cells exposed to bimatoprost with BAK demonstrated significant reductions in the percentage of live cells compared with PBS (P = 0.02). For 1:10 dilutions using manual cell count, cells exposed to bimatoprost with BAK, latanoprost with BAK, and BAK alone demonstrated significantly greater toxicity than PBS, travoprost with PQ, PQ alone, and tafluprost PF (all P ≤ 0.03). No significant differences were observed among PBS, travoprost with PQ, and PQ alone under any test conditions (P ≤ 0.63).

CONCLUSION

This study demonstrated that BAKcontaining solutions, including bimatoprost 0.01% with BAK, were toxic to human corneal epithelial cells, whereas BAK-free solutions showed little to no evidence of toxicity.