Current and emerging medical therapies in the treatment of glaucoma

Posterior Segment Ophthalmic Drug Delivery: Role of Muco-Adhesion with a Special Focus on Chitosan

Posterior segment eye diseases (PSEDs) including age macular degeneration (AMD) and diabetic retinopathy (DR) are amongst the major causes of irreversible blindness worldwide. Due to the numerous barriers encountered, highly invasive intravitreal (IVT) injections represent the primary route to deliver drugs to the posterior eye tissues. Thus, the potential of a more patient friendly topical route has been widely investigated. Mucoadhesive formulations can decrease precorneal clearance while prolonging precorneal residence. Thus, they are expected to enhance the chances of adherence to corneal and conjunctival surfaces and as such, enable increased delivery to the posterior eye segment. Among the mucoadhesive polymers available, chitosan is the most widely explored due to its outstanding mucoadhesive characteristics. In this review, the major PSEDs, their treatments, barriers to topical delivery, and routes of topical drug absorption to the posterior eye are presented. To enable the successful design of mucoadhesive ophthalmic drug delivery systems (DDSs), an overview of mucoadhesion, its theory, characterization, and considerations for ocular mucoadhesion is given. Furthermore, chitosan-based DDs that have been explored to promote topical drug delivery to the posterior eye segment are reviewed. Finally, challenges of successful preclinical to clinical translation of these DDSs for posterior eye drug delivery are discussed.

A Review on Newer Ocular Drug Delivery Systems with an Emphasis on Glaucoma

Glaucoma is an irreversible condition resulting from the increase in intraocular pressure (IOP); which leads to permanent loss of vision with the destruction of retinal ganglion cells (RGCs). The IOP elevations are controlled in normal by the physiological flow of aqueous humour. A population with age above 40 is more susceptible to glaucoma. Other factors like gender, genetics, race etc. plays major roles in the development of the disease. Current treatment methods available for the disease includes drugs come under the classes of beta receptor blockers, carbonic anhydrase inhibitors, cholinergic agonists, prostaglandins etc. N-methyl-D-aspartate (NMDA) antagonists, inducible nitric oxide synthase (iNOS) inhibition, cytoskeletal agents, Rho-kinase inhibitors etc are few novel targets sites which are in research focus for the treatment of the disease. Developments in nanomedicine are also being evaluated for their potential in treating the growing glaucomatous population. Nanosystems are suggested to avoid the difficulties in tackling the various ocular barriers to a limit, help to decrease the instillation frequency of topical medication and can provide drug delivery in a sustained or controlled manner. This review focuses on the current and emerging treatment methods for glaucoma along with some of the nanoformulations for ocular drug delivery.

Effects of Ab Interno XEN Gel Implantation on Postural Intraocular Pressure Elevations

Purpose: The aim of this study was to analyze the postural intraocular pressure (IOP) changes in open-angle glaucoma after ab interno XEN gel implant surgery and to compare them with the changes observed with trabeculectomy and medical treatment.Patients and Methods: The study sample included 18 patients with XEN gel implants, 30 patients who had trabeculectomy, and 30 medically managed glaucoma patients. All patients in XEN gel implant and trabeculectomy groups had at least 11 months of follow-up and had successful surgeries that resulted in medication-free control of IOP. A rebound tonometer (Icare, Finland Oy, Helsinki, Finland) was used to measure the IOP levels at the sitting, supine, and dependent lateral decubitus (DLDP) positions after a 5-minute rest at each position.Results: In all the groups, the mean IOP values in the DLDP and supine positions were significantly higher than the sitting position. The IOP elevation after moving from sitting to supine position was significantly reduced in XEN gel implant and trabeculectomy groups compared to medical treatment group (p = .001 and p = .002, respectively). The IOP elevation after a moving from sitting to DLDP was also significantly reduced in XEN gel implant and trabeculectomy groups compared to the medical treatment group (p = .003 and p = .01, respectively). However, there was no significant difference in IOP change after moving from sitting to supine or DLDP positions between XEN gel implant and trabeculectomy groups (p = .74 and p = .98, respectively).Conclusion: This study demonstrated that XEN gel implant could reduce postural elevations in IOP to the same degree as trabeculectomy and provide significantly better postural IOP control than medical treatment. This surgery can be an effective minimally invasive alternative for patients with significant positional IOP elevations.

Proteome alterations in aqueous humour of primary open angle glaucoma patients

AIM

To unravel the primary open angle glaucoma (POAG) related proteomic changes in aqueous humour (AH).

METHODS

Totally 35 patients listed for cataract surgery (controls: n=12, age: 67.4±13.6y) or trabeculectomy for POAG (n=23, age: 72.5±8.3y) were included. AH samples of those patients were obtained during cataract surgery or trabeculectomy. AH samples were subsequently pooled into the experimental groups under equal contribution in terms of protein amount of each individual patient. Protein samples were analyzed by a linear trap quadrupol Orbitrap Mass Spectrometry device with an upstream liquid chromatography system. The obtained raw data were analyzed using the Maxquant proteome software and compared. Proteins with a fold-change ratio higher than a cut-off of 2 were considered as noticeably altered.

RESULTS

A total number of 175 proteins could be identified out of the AH from POAG and cataract by means of quantitative mass spectrometric analysis. Apolipoprotein D (fold change, 3.16 times), complement C3 (2.96), pigment epithelium-derived factor (2.86), dickkopf-related protein 3 (2.18) and wingless-related integration (Wnt) inhibitory factor 1 (2.35) were significantly upregulated within the AH of glaucoma compared to cataract serving as controls.

CONCLUSION

AH provides a tool to analyze changes in glaucoma and shows striking changes in Wnt signaling inhibitory molecules and other proteins.

Retinal Astrocytes and GABAergic Wide-Field Amacrine Cells Express PDGFRα: Connection to Retinal Ganglion Cell Neuroprotection by PDGF-AA

Purpose

Our previous experiments demonstrated that intravitreal injection of platelet-derived growth factor-AA (PDGF-AA) provides retinal ganglion cell (RGC) neuroprotection in a rodent model of glaucoma. Here we used PDGFRα-enhanced green fluorescent protein (EGFP) mice to identify retinal cells that may be essential for RGC protection by PDGF-AA.

Methods

PDGFRα-EGFP mice expressing nuclear-targeted EGFP under the control of the PDGFRα promoter were used. Localization of PDGFRα in the neural retina was investigated by confocal imaging of EGFP fluorescence and immunofluorescent labeling with a panel of antibodies recognizing different retinal cell types. Primary cultures of mouse RGCs were produced by immunopanning. Neurobiotin injection of amacrine cells in a flat-mounted retina was used for the identification of EGFP-positive amacrine cells in the inner nuclear layer.

Results

In the mouse neural retina, PDGFRα was preferentially localized in the ganglion cell and inner nuclear layers. Immunostaining of the retina demonstrated that astrocytes in the ganglion cell layer and a subpopulation of amacrine cells in the inner nuclear layer express PDGFRα, whereas RGCs (in vivo or in vitro) did not. PDGFRα-positive amacrine cells are likely to be Type 45 gamma-aminobutyric acidergic (GABAergic) wide-field amacrine cells.

Conclusions

These data indicate that the neuroprotective effect of PDGF-AA in a rodent model of glaucoma could be mediated by astrocytes and/or a subpopulation of amacrine cells. We suggest that after intravitreal injection of PDGF-AA, these cells secrete factors protecting RGCs.

Myofibroblast transdifferentiation: The dark force in ocular wound healing and fibrosis

Wound healing is one of the most complex biological processes to occur in life. Repair of tissue following injury involves dynamic interactions between multiple cell types, growth factors, inflammatory mediators and components of the extracellular matrix (ECM). Aberrant and uncontrolled wound healing leads to a non-functional mass of fibrotic tissue. In the eye, fibrotic disease disrupts the normally transparent ocular tissues resulting in irreversible loss of vision. A common feature in fibrotic eye disease is the transdifferentiation of cells into myofibroblasts that can occur through a process known as epithelial-mesenchymal transition (EMT). Myofibroblasts rapidly produce excessive amounts of ECM and exert tractional forces across the ECM, resulting in the distortion of tissue architecture. Transforming growth factor-beta (TGFβ) plays a major role in myofibroblast transdifferentiation and has been implicated in numerous fibrotic eye diseases including corneal opacification, pterygium, anterior subcapsular cataract, posterior capsular opacification, proliferative vitreoretinopathy, fibrovascular membrane formation associated with proliferative diabetic retinopathy, submacular fibrosis, glaucoma and orbital fibrosis. This review serves to introduce the pathological functions of the myofibroblast in fibrotic eye disease. We also highlight recent developments in elucidating the multiple signaling pathways involved in fibrogenesis that may be exploited in the development of novel anti-fibrotic therapies to reduce ocular morbidity due to scarring.

Long Term Glaucoma Drug Delivery Using a Topically Retained Gel/Microsphere Eye Drop

The purpose of this study was to characterize and determine the efficacy of a long-term, non-invasive gel/microsphere (GMS) eye drop for glaucoma. This novel drug delivery system is comprised of a thermoresponsive hydrogel carrier and drug-loaded polymer microspheres. In vitro release of brimonidine from the GMS drops and gel properties were quantified. A single brimonidine-loaded GMS drop was administered to 5 normotensive rabbits and intraocular pressure (IOP) was monitored for 28 days. Here we report that IOP reduction in rabbits receiving a single brimonidine GMS drop was comparable to that of rabbits receiving twice daily, standard brimonidine drops. GMS drops were retained in the inferior fornix in all animals for the length of the study. Our results suggest in vivo efficacy over 28 days from a single GMS drop and a potential decrease in systemic absorption, based on a lack of substantial IOP effects on the fellow untreated eye, compared to brimonidine twice-daily eye drops. To our knowledge, this represents the first long-term, drug-releasing depot that can be administered as a traditional eye drop.

Evaluation of the anti-Acanthamoeba activity of two commercial eye drops commonly used to lower eye pressure

Efficient treatments against Acanthamoeba Keratitis (AK), remains until the moment, as an issue to be solved due to the existence of a cyst stage which is highly resistant to most chemical and physical agents. In this study, two antiglaucoma eye drops were tested for their activity against Acanthamoeba. Moreover, this study was based on previous data which gave us evidence of a possible link between the absences of Acanthamoeba at the ocular surface in patients treated with beta blockers for high eye pressure both containing timolol as active principle. The amoebicidal activity of the tested eye drops was evaluated against four strains of Acanthamoeba using Alamar blue method. For the most active drug the cysticidal activity against A. castellanii Neff cysts and further experiments studying changes in chromatin condensation levels, in the permeability of the plasmatic membrane, the mitochondrial membrane potential and the ATP levels in the treated amoebic strains were done. Even though both eye drops were active against the different tested strains of Acanthamoeba, statistical analysis revealed that one of them (Timolol Sandoz) was the most effective one against all the tested strains presenting IC_50s ranging from 0.529% ± 0.206 for the CLC 16 strain to 3.962% ± 0.150 for the type strain Acanthamoeba castellanii Neff. Timolol Sandoz 0.50% seems to induce amoebic cell death by damaging the amoebae at the mitochondrial level. Considering its effect, Timolol Sandoz 0.50% could be used in the case of contact lens wearers and patients with glaucoma.

Efficacy and Tolerability of Travoprost 0.004%/Timolol 0.5% Fixed-Dose Combination for the Treatment of Primary Open-Angle Glaucoma or Ocular Hypertension Inadequately Controlled with Beta-Blocker Monotherapy

Objective. To evaluate the efficacy and tolerability of travoprost 0.004%/timolol 0.5% fixed-dose combination (TTFC) in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT) inadequately controlled on beta-blocker monotherapy. Methods. In this phase IV, open-label study, 156 patients on beta-blocker monotherapy with mean intraocular pressure (IOP) between 18 and 32 mmHg were randomized (no washout period) to receive TTFC for 8 weeks (TTFC group) or to continue beta-blocker monotherapy for 4 weeks followed by TTFC for the remaining 4 weeks (beta-blocker group). Results. The mean IOP (±standard deviation) at baseline in the TTFC and beta-blocker groups was 22.5 ± 2.5 mmHg and 22.2 ± 2.3 mmHg, respectively, and at weeks 4 and 8, was 16.7 ± 3.1 mmHg and 16.1 ± 3.1 mmHg, respectively, in TTFC group and 21.1 ± 3.1 mmHg and 16.1 ± 2.8 mmHg, respectively, in the beta-blocker group. There was a significant least squares mean difference between TTFC and beta-blocker in 8 a.m. IOP at week 4 (−4.6 mmHg; one-sided 95% confidence interval [−inf, −3.9]; p < 0.0001 [primary endpoint]); the upper bound of the 95% confidence interval was within the prespecified limit (<0). Both treatments were well tolerated. Conclusion. Superior IOP control was achieved with TTFC in patients with OAG or OHT previously uncontrolled with beta-blockers. No new safety findings were identified. This trial is registered with ClinicalTrials.gov NCT02003391.

Benefits of switching from latanoprost to preservative-free tafluprost eye drops: a meta-analysis of two Phase IIIb clinical trials

INTRODUCTION

Glaucoma patients frequently exhibit ocular surface side effects during treatment with prostaglandin eye drops. The present work investigated whether glaucoma patients suffering from signs and symptoms of ocular surface disease while using preserved latanoprost eye drops benefited from switching to preservative-free tafluprost eye drops.

PATIENTS AND METHODS

The analysis was based on 339 glaucoma patients enrolled in two Phase IIIb trials. The patients were required to have two symptoms, or one sign and one symptom of ocular surface disease at baseline, and at least 6 months preceding treatment with latanoprost eye drops preserved with benzalkonium chloride. All eligible patients were switched from latanoprost to preservative-free tafluprost for a total of 12 weeks. Ocular symptoms and ocular signs were evaluated at baseline and at 2 weeks, 6 weeks, and 12 weeks after commencing treatment with tafluprost. Intraocular pressure (IOP), drop discomfort, and treatment preference were evaluated to investigate the clinical efficacy and patient-related outcomes.

RESULTS

After 12 weeks of treatment with preservative-free tafluprost, the incidences of irritation/burning/stinging, foreign body sensation, tearing, itching, and dry eye sensation had diminished to one-third of those reported for preserved latanoprost at baseline. The incidences of blepharitis and corneal/conjunctival fluorescein staining had in turn decreased to one-half of those reported for preserved latanoprost. Severity of conjunctival hyperemia was halved during treatment with preservative-free tafluprost, and there was significant improvement in tear break-up time and tear production. A further reduction in IOP (~1 mmHg) was seen with preservative-free tafluprost compared with preserved latanoprost. Drop discomfort was alleviated during preservative-free tafluprost treatment, and an outstanding majority of patients (72%) preferred preservative-free tafluprost over preserved latanoprost.

CONCLUSION

This meta-analysis confirmed that IOP remained at the same level after replacing benzalkonium chloride-preserved latanoprost eye drops with preservative-free tafluprost eye drops. Preservative-free tafluprost significantly decreased the symptoms and signs of ocular surface disease and outrated latanoprost in drop comfort and treatment preference.

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.

Discovery of Molecular Therapeutics for Glaucoma: Challenges, Successes, and Promising Directions

Glaucoma, a heterogeneous ocular disorder affecting ∼60 million people worldwide, is characterized by painless neurodegeneration of retinal ganglion cells (RGCs), resulting in irreversible vision loss. Available therapies, which decrease the common causal risk factor of elevated intraocular pressure, delay, but cannot prevent, RGC death and blindness. Notably, it is changes in the anterior segment of the eye, particularly in the drainage of aqueous humor fluid, which are believed to bring about changes in pressure. Thus, it is primarily this region whose properties are manipulated in current and emerging therapies for glaucoma. Here, we focus on the challenges associated with developing treatments, review the available experimental methods to evaluate the therapeutic potential of new drugs, describe the development and evaluation of emerging Rho-kinase inhibitors and adenosine receptor ligands that offer the potential to improve aqueous humor outflow and protect RGCs simultaneously, and present new targets and approaches on the horizon.

Current perspective of neuroprotection and glaucoma

Glaucoma is the second leading cause of blindness worldwide and is most notably characterized by progressive optic nerve atrophy and advancing loss of retinal ganglion cells (RGCs). The main concomitant factor is the elevated intraocular pressure (IOP). Existing treatments are focused generally on lowering IOP. However, both RGC loss and optic nerve atrophy can independently occur with IOP at normal levels. In recent years, there has been substantial progress in the development of neuroprotective therapies for glaucoma in order to restore vital visual function. The present review intends to offer a brief insight into conventional glaucoma treatments and discuss exciting current developments of mostly preclinical data in novel neuroprotective strategies for glaucoma that include recent advances in noninvasive diagnostics going beyond IOP maintenance for an enhanced global view. Such strategies now target RGC loss and optic nerve damage, opening a critical therapeutic window for preventative monitoring and treatment.

Efficacy of a preservative-free formulation of fixed-combination bimatoprost and timolol (Ganfort PF) in treatment-naïve patients vs previously treated patients

PURPOSE

To evaluate, using subgroup analysis, the effect of treatment status on the intraocular pressure (IOP)-lowering efficacy of a preservative-free formulation of fixed-combination bimatoprost 0.03%/timolol 0.5% (FCBT PF).

METHODS

A primary, multicenter, randomized, double-masked, 12-week study compared the efficacy and safety of FCBT PF with preserved FCBT (Ganfort(®)) in 561 patients diagnosed with glaucoma or ocular hypertension. For this analysis, eligible patients were treatment-naïve or had inadequate IOP lowering and underwent a washout of previous treatment. IOP (8 am, 10 am, and 4 pm) was measured at baseline and weeks 2, 6, and 12. Subgroup analysis of the FCBT PF arm assessed changes in average eye IOP from baseline in treatment-naïve vs previously treated patients. To evaluate the effect of treatment status at baseline (treatment-naïve vs previously treated) on IOP reduction in the FCBT PF treatment group, an analysis of covariance model was used with treatment status and investigator as fixed effects, and baseline average eye IOP, age, glaucoma diagnosis, and baseline average eye corneal thickness as covariates. P-values and the 95% confidence intervals were determined using the model.

RESULTS

In the FCBT PF arm, IOP mean changes from baseline ranged from -8.7 mmHg to -9.8 mmHg in treatment-naïve patients (N=50), compared with -7.3 mmHg to -8.5 mmHg in previously treated patients (N=228). Baseline IOP, age, glaucoma diagnosis, and corneal thickness significantly affected IOP reduction in the FCBT PF group. Adjusting for these covariates, FCBT PF had a greater IOP-lowering effect (0.8-1.7 mmHg) in treatment-naïve patients than previously treated patients, which was statistically significant (P≤0.05) at seven of nine time points.

CONCLUSION

In this subgroup analysis, FCBT PF reduced IOP more effectively in treatment-naïve than in previously treated patients possibly due, in part, to altered responsiveness or tachyphylaxis that has been associated with prior ocular hypotensive agent treatment.

Bimatoprost 0.01 % for previously treated patients with open-angle glaucoma or ocular hypertension in the Korean clinical setting

PURPOSE

To evaluate the occurrence of hyperemia with, and efficacy of, bimatoprost 0.01 % for patients in Korea previously treated for open-angle glaucoma (OAG; including normal tension glaucoma) or ocular hypertension (OHT).

METHODS

In this multicenter, observational study (Asia Pacific Patterns from Early Access of Lumigan 0.01 % in Korea; APPEAL Korea), patients with unachieved target intraocular pressure (IOP) despite previous treatment received bimatoprost 0.01 % daily for 12 weeks. The primary endpoint was incidence of hyperemia and its severity, graded using the standard 5-point photographic scale and grouped as "none to mild" and "moderate to severe". Hyperemia shifts were reported. IOP and adverse events (AEs) were recorded.

RESULTS

Of 800 patients (intent-to-treat/safety population), 248 were switched from previous treatment to bimatoprost 0.01 % monotherapy. Hyperemia shifts from baseline at weeks 6 and 12 were unchanged (84.8, 89.8 %), improved (4.4, 4.8 %), or worsened (10.8, 5.4 %), respectively. The shift was significant at week 6 (P < 0.0001). Hyperemia did not worsen significantly in patients previously receiving a prostaglandin analog or prostamide (PGA/PSD). Baseline mean IOP ± SD was 17.0 ± 5.7 mmHg, decreasing to 14.6 ± 3.8 mmHg (P < 0.0001) after 6 weeks, and to 14.7 ± 3.6 mmHg (P < 0.0001) after 12 weeks. Patients switched from PGA or PSD (excluding bimatoprost 0.03 %) to bimatoprost 0.01 % experienced significant IOP reductions from baseline. Treatment-related ocular AEs were reported by 37 patients, the most common being hyperemia (7.3 %).

CONCLUSIONS

This subanalysis of the APPEAL Korea study supports use of bimatoprost 0.01 % for previously treated patients with OAG (including normal tension glaucoma) or OHT who did not reach target IOP or were intolerant of previous treatment.

Different strategies and cost-effectiveness in the treatment of primary open angle glaucoma

Glaucoma is the second highest cause of blindness worldwide with an estimated half of the glaucoma population unaware of their disease. To date, intraocular pressure is the most important modifiable risk factor and lowering it has been proven to reduce progression of visual field loss associated with glaucoma. Different strategies are available to lower intraocular pressure and include medical, laser, or surgical treatment in the form of topical or systemic medications, argon or selective laser trabeculoplasty, and glaucoma drainage surgery such as trabeculectomy, deep sclerectomy, or other drainage devices. The effectiveness of these treatments has been well documented however their cost-effectiveness between the developed world and third world remains unclear.

Bioactive lysophospholipids: role in regulation of aqueous humor outflow and intraocular pressure in the context of pathobiology and therapy of glaucoma

Homeostasis of aqueous humor (AH) outflow and intraocular pressure (IOP) is essential for normal vision. Impaired AH outflow through the trabecular meshwork (TM) and a resultant elevation in IOP are common changes in primary open-angle glaucoma (POAG), which is the most prevalent form of glaucoma. Although elevated IOP has been recognized as a definitive risk factor for POAG and lowering elevated IOP remains a mainstay for glaucoma treatment, little is known about the molecular mechanisms, especially external cues and intracellular pathways, involved in the regulation of AH outflow in both normal and glaucomatous eyes. In addition, despite the recognition that increased resistance to AH outflow via the conventional pathway consisting of TM and Schlemm's canal is the main cause for elevated IOP, there are no clinically approved drugs that target the conventional pathway to lower IOP in glaucoma patients. The aim of this article is to briefly review published work on the importance of bioactive lysophospholipids (eg, lysophosphatidic acid and sphingosine-1-phosphate), their receptors, metabolism, signaling, and role in the regulation of AH outflow via the TM and IOP, and to discuss pharmacological targeting of key proteins in the lysophospholipid signaling pathways to lower IOP in glaucoma patients.

Phase 2 randomized clinical study of a Rho kinase inhibitor, K-115, in primary open-angle glaucoma and ocular hypertension

PURPOSE

To identify the optimal dose of a novel Rho kinase inhibitor, K-115, by assessing dose dependency of the intraocular pressure (IOP)-lowering effects and the safety in patients with primary open-angle glaucoma or ocular hypertension.

DESIGNS

Multicenter, prospective, randomized, placebo-controlled, double-masked, parallel group comparison clinical study.

METHODS

After appropriate washout periods, 210 patients with primary open-angle glaucoma or ocular hypertension were subdivided into 4 groups and were treated with K-115 in concentrations of 0.1%, 0.2%, and 0.4% or placebo twice daily for 8 weeks. The dose response of IOP reduction and the incidence of adverse events by K-115 or placebo were investigated.

RESULTS

The mean baseline IOP was between 23.0 and 23.4 mm Hg. The mean IOP reductions of the last visit from baseline were -2.2 mm Hg, -3.4 mm Hg, -3.2 mm Hg, and -3.5 mm Hg, respectively, in the placebo, 0.1%, 0.2%, and 0.4% groups at before instillation (9:00); -2.5 mm Hg, -3.7 mm Hg, -4.2 mm Hg, and -4.5 mm Hg at 2 hours after instillation (11:00); and -1.9 mm Hg, -3.2 mm Hg, -2.7 mm Hg, and -3.1 mm Hg at 8 hours after instillation (17:00). The dose-dependent IOP-lowering effect of K-115 was statistically significant at all time points. Also, conjunctival hyperemia was found in 7 (13.0%) of 54 patients for placebo, 23 (43.4%) of 53 patients for the 0.1% group, 31 (57.4%) of 54 patients for the 0.2% group, and 32 (65.3%) of 49 patients for the 0.4% group.

CONCLUSIONS

On the basis of this dose-response study, K-115 0.4% has been selected to be the optimal dose and has the potential to be a promising new agent for glaucoma to control 24-hour IOP by twice-daily dosing.

Adenosine A1 modulators: a patent update (2008 to present)

INTRODUCTION

In 2008, we published our review titled 'Therapeutic potential of A1 adenosine receptor ligands - a survey of recent patent literature' that reported the compounds active on A1 adenosine receptors (ARs) and the applications of A1 AR ligands patented in the period 2005 - 2008.

AREAS COVERED

This article is a discussion of the patents about the same subjects, issued in the period 2008 to present. It is organized similarly to the first one, with a section about new compounds, subdivided on the basis of their functional activity (agonists, antagonists and allosteric modulators) and a section regarding new therapeutic applications.

EXPERT OPINION

The main novelty is represented by the patenting of A1 AR ligands with dual selectivity which may show, in some conditions, better efficacy and fewer side effects. Moreover, while the way to arrive into the market appears full of obstacles for selective A1 ligands that need systemic administration for long-term therapy, better chances are foreseen in applications requiring topical administration.

Antiglaucoma drugs: The role of preservative-free formulations

Hypersensitive reactions to eyedrops are a common finding in clinical practice and represent a frequent cause of discontinuation of the therapy. Moreover, experimental and clinical studies show that long term use of topical drugs may induce ocular surface changes causing discomfort and potentially negatively affecting the compliance to the treatment as well as the success rate of filtering procedures. The exact mechanism involved and the roles of the active compound and the preservatives in inducing such detrimental effects of ophthalmic solutions are unclear. During the last years several antiglaucoma agents have been marketed as either preservative-free or benzalkonium chloride-free formulations in an attempt to reduce the adverse effects related to preservatives. This paper summarizes the body of evidence from existing studies about preservatives in antiglaucoma eyedrops, focusing on the latest compounds commercially available. A systematic review of the literature was performed. Current research is focusing not only on the efficacy of the drugs but also on their tolerability. Based on the existing data, there is a rationale to support the use of benzalkonium-free solutions whenever possible, especially in patients suffering from concomitant ocular surface diseases, experiencing local side effects and in those expected to need multiple and prolonged topical treatments.