Brimonidine in the treatment of glaucoma and ocular hypertension

Preclinical Evaluation of a Novel Once-a-Day Brimonidine Ophthalmic Nanosuspension

Purpose: This article aims to describe a preclinical proof of concept for a novel once-a-day (OD) brimonidine ophthalmic nanosuspension. Methods: The preclinical proof of concept was established using New Zealand white rabbits as animal models. Dose-finding, multiple-dose efficacy, ocular pharmacokinetic, and hemodynamic studies were performed in normotensive rabbits. Steroid-induced ocular hypertension model in rabbits was used to study efficacy in glaucomatous pathophysiology. The test (0.35% OD suspension) and reference (0.15% three times a day [TID] solution) were compared. Results: The intraocular pressure (IOP) reduction was sustained for 0.35% and 0.5% strengths but not for other lower strengths tested or reference strengths. A 0.35% OD suspension reduced IOP >2 mmHg after 24 h of dosing, which was not seen with the reference. After multiple dosing, 0.35% OD suspension reduced IOP by 4-6 mmHg after 24 h, which was comparable to the 0.15% TID reference solution. An ocular pharmacokinetic study showed that the brimonidine was rapidly absorbed and distributed throughout the eye after topical administration. Concentration was higher in tissues with high α2 receptors, such as cornea-conjunctiva, iris/ciliary body, and choroid/retina. The steady-state concentrations in these organs were also significant after 24 h of the last dose. There was an indication of increased plasma levels, so a hemodynamic study was performed to assess any adverse effects. All hemodynamic parameters were normal and no new unusual safety findings were observed. Conclusions: The study demonstrated that the novel brimonidine 0.35% ophthalmic nanosuspension is both safe and effective when administered OD and is comparable to the marketed reference formulation administered TID.

Biomaterial Drug Delivery Systems for Prominent Ocular Diseases

Ocular diseases, such as age-related macular degeneration (AMD) and glaucoma, have had a profound impact on millions of patients. In the past couple of decades, these diseases have been treated using conventional techniques but have also presented certain challenges and limitations that affect patient experience and outcomes. To address this, biomaterials have been used for ocular drug delivery, and a wide range of systems have been developed. This review will discuss some of the major classes and examples of biomaterials used for the treatment of prominent ocular diseases, including ocular implants (biodegradable and non-biodegradable), nanocarriers (hydrogels, liposomes, nanomicelles, DNA-inspired nanoparticles, and dendrimers), microneedles, and drug-loaded contact lenses. We will also discuss the advantages of these biomaterials over conventional approaches with support from the results of clinical trials that demonstrate their efficacy.

Triple Fixed-Combination Bimatoprost/Brimonidine/Timolol in Glaucoma and Ocular Hypertension in India: A Multicenter, Open-Label, Phase 3 Study

Introduction

To evaluate the intraocular pressure (IOP)-lowering efficacy and safety of a triple fixed-combination of bimatoprost, brimonidine, and timolol (TFC) in patients with glaucoma or ocular hypertension (OHT) treated with fixed-combination or unfixed brimonidine and timolol therapy (dual-combination therapy).

Methods

In this multicenter, open-label, phase 3 study, patients who received 4-8 weeks of dual-combination therapy twice daily and had an IOP >18 and <34 mmHg in at least one eye were switched (at baseline) to treatment with TFC twice daily for 12 weeks. At Weeks 4, 8, and 12 on TFC, IOP was assessed at Hours 0, 2, and 8. Primary efficacy variable: mean diurnal IOP change from baseline in the study eye at Week 12 (modified intent-to-treat [mITT] population). Sensitivity (per-protocol [PP] population) and subgroup (≤65 vs >65 years) analyses were performed. Safety, including adverse events (AEs), was assessed at each visit.

Results

Of 126 patients enrolled, 121 and 103 formed the mITT/safety and PP populations, including 109 (90.1%) and 94 (91.3%) who completed the study, respectively. In the mITT/safety population, mean age was 58.6 years. Patients had open-angle glaucoma (51.2%), angle-closure glaucoma with patent iridotomy (36.4%), and/or OHT (13.2%). At Week 12, the mean diurnal change in IOP from dual combination-treated baseline was statistically significant (P<0.001) with TFC in the mITT (-3.98 mmHg) and PP (-4.22 mmHg) populations. Results were similar at all visits, regardless of the age subgroup. The most frequent treatment-related AEs were conjunctival hyperemia (14.0%) and dry eye (4.1%); 5.8% of the patients discontinued treatment due to ocular AEs.

Conclusion

TFC offers a beneficial therapeutic alternative for patients with glaucoma or OHT whose IOP is not sufficiently controlled with dual-combination therapy. Safety and efficacy findings support those of published studies of TFC in primary open-angle glaucoma and OHT, despite differences in study designs.

Potential of pectin for biomedical applications: a comprehensive review

Pectin is a polysaccharide extracted from various plants, such as apples, oranges, lemons, and it possesses some beneficial effects on human health, including being hypoglycemic and hypocholesterolemic. Therefore, pectin is used in various pharmaceutical and biomedical applications. Meanwhile, its low mechanical strength and fast degradation rate limit its usage as drug delivery devices and tissue engineering scaffolds. To enhance these properties, it can be modified or combined with other organic molecules or polymers and/or inorganic compounds. These materials can be prepared as nano sized drug carriers in the form of spheres, capsules, hydrogels, self assamled micelles, etc., for treatment purposes (mostly cancer). Different composites or blends of pectin can also be produced as membranes, sponges, hydrogels, or 3D printed matrices for tissue regeneration applications. This review is concentrated on the properties of pectin based materials and focus especially on the utilization of these materials as drug carriers and tissue engineering scaffolds, including 3D printed and 3D bioprinted systems covering the studies in the last decade and especially in the last 5 years.

An α2-Adrenergic Agonist, Brimonidine, Beneficially Affects the TGF-β2-Treated Cellular Properties in an In Vitro Culture Model

We report herein on the effects of brimonidine (BRI), an α2-adrenergic agonist, on two-dimensional (2D) and three-dimensional (3D) cell-cultured TGF-β2-untreated and -treated human trabecular meshwork (HTM) cells. In the presence of TGF-β2 (5 ng/mL), (1) the effects of BRI on (1) the 2D HTM monolayers’ barrier function were investigated as estimated using trans-endothelial electrical resistance (TEER) measurement and FITC dextran permeability; (2) real-time analyses of cellular metabolism using a Seahorse Bioanalyzer; (3) the largeness and hardness of 3D spheroids; and (4) the expression of genes that encode extracellular matrix (ECM) proteins, including collagens (COL) 1, 4, and 6; fibronectin (FN) and α-smooth muscle actin (α-SMA); ECM modulators, including a tissue inhibitor of matrix proteinase (TIMP) 1–4; matrix metalloproteinase (MMP) 2, 9, and 14; and several endoplasmic reticulum (ER) stress-related genes, including the X-box-binding protein 1 (XBP1), the spliced XBP1 (sXBP1), glucose-regulated protein (GRP)78, GRP94, and CCAAT-enhancer-binding protein homologous protein (CHOP). BRI markedly inhibited the TGF-β2-induced increase in the values of TEER of the 2D cell monolayer and the hardness of the 3D spheroids, although it had no effect on their sizes. BRI also cancelled the TGF-β2-induced reduction in mitochondrial maximal respiration but had no effect on the glycolytic capacity. In addition, the gene expression of these molecules was quite different between the 2D and 3D cultures of HTM cells. The present observations found in this study indicate that BRI may beneficially affect TGF-β2-induced changes in both cultures, 2D and 3D, of HTM cells, although their structural and functional properties that were altered varied significantly between both cultures of HTM cells.

Cannabis, Intraocular Pressure, and the Growth Arrest-Specific 7 (GAS7) Gene: A Retrospective Analysis

Background Intraocular pressure (IOP) is a highly heritable risk factor for primary open-angle glaucoma (POAG), with at least 27 related genes; however, we are still not aware as to which receptors or genes that the main components of cannabis use to lower IOP. Methods In the current study, we used data from the UK Biobank (UKBB) to assess the relationship of growth arrest-specific 7 (GAS7) with IOP and cannabis in 37,046 subjects. GAS7, at chromosome 17p31.1, is quite close to a cannabis receptor at chromosome 17p31.3. For comparison, we chose a second IOP/glaucoma gene, CDKN2B-AS1 on chromosome 9p21.3, with no known relationship to cannabis. In addition, we examined the effect of CB1, GPR18, and cannabis on IOP; these two genes are associated with cannabis IOP reduction in mice. Results Total cannabis use versus IOP and genotypes of GAS7 SNP rs9913911 in the 37,046 subjects showed significant variation [p<0.001, univariate analysis of variance (ANOVA)]. Carriers of the GAS7 rs9913911 minor allele G had lower IOP with increased cannabis use. Total cannabis use versus IOP of genotypes of CDKN2B-AS1 SNP rs944801 in 37,046 subjects had IOP variability with cannabis use that was insignificant (p=0.138). We analyzed the relationship of CB1 SNP rs806365 and GPR18 SNP rs3742130 with cannabis use and IOP, which was insignificant. CB1 and GPR18 are probably not involved in cannabis-associated human IOP reduction, unlike what has been reported in mice. Conclusion Cannabis-based treatments, which apparently act on the GAS7 gene, can be utilized to reduce IOP. However, their disadvantages outweigh their advantages, which was not the case when the initial reports of marijuana's effects on IOP were published in the 1970s. Hence, cannabis-based glaucoma treatments are now of questionable value.

Effect of Topical Dexmedetomidine (0.0055%) on Intraocular Pressure in Healthy Eyes: A Randomized Controlled Trial

Aim and objective

Evaluate the short-term safety and efficacy of dexmedetomidine (0.0055%) drops on intraocular pressure (IOP) in healthy eyes.

Materials and methods

In this randomized controlled trial, patients with normal eye exams were randomly assigned to receive, in a randomly selected eye, one drop of either balanced salt solution (BSS) or dexmedetomidine (0.0055%). Goldmann applanation tonometry was performed at baseline and then 30 minutes, 4 hours, and 24 hours after drop instillation.

Results

Forty-nine eyes of 49 normal volunteers were enrolled in the study, with 21 eyes (group I) receiving BSS and 28 (group II) dexmedetomidine. Both groups were comparable at baseline as far as age and IOP (p = 0.55 for both parameters). Intraocular pressure significantly decreased from baseline in group II at 30 minutes and 4 hours (p = 0.001 and 0.05, respectively). Maximum IOP decrease was obtained at 30 minutes after dexmedetomidine instillation, with a 9% decrease from baseline (mean decrease: 1.15 mm Hg). The percentage of IOP decrease was significantly higher in group II at 30 minutes compared with group I (9 vs 1.1%; p = 0.05). No side effects were recorded.

Conclusion

In this pilot study, dexmedetomidine 0.0055% drops have shown good safety and efficacy in lowering IOP in normal healthy volunteers with no history of glaucoma. This medication has a short onset of action, with a 10% reduction of IOP occurring 30 minutes post-instillation.

Trial registration number

NCT03690622.

How to cite this article

Fakhoury H, Abdelmassih Y, El-Khoury S, et al. The Effect of Topical Dexmedetomidine (0.0055%) on Intraocular Pressure in Healthy Eyes: A Randomized Controlled Trial. J Curr Glaucoma Pract 2021;15(2):58-63.

Novel cubosome based system for ocular delivery of acetazolamide

Acetazolamide is the drug of choice for glaucoma treatment in an emergency. However, it is not available in any topical formulation and it is available only as systemic tablets. Despite its efficiency as a drug in decreasing intraocular pressure, it has negative systemic effects as renal toxicity and metabolic acidosis. Moreover, it suffers from poor aqueous solubility and low corneal permeability limiting its ocular bioavailability and its use topically. Cubosomes have enormous advantages as a drug delivery system, most importantly, high surface area, thermal stability, and ability to encapsulate hydrophobic, amhiphilic, and hydrophilic molecules. Herein, we have exploited the unique properties of cubosomes as a novel nano-delivery system for acetazolamide as eye drops dosage form for glaucoma treatment. Different acetazolamide-loaded cubosomes have been developed and evaluated. The best-optimized formulation (F5), was cubic shaped structure, with an average particle size of 359.5 ± 2.8 nm, surface charge −10.8 ± 3.2 mV, and 59.8% entrapment efficiency. Ex-vivo corneal permeation studies have revealed a 4-fold increase in acetazolamide permeability coefficient compared to that stated in the literature. F5 showed superior therapeutic efficacy represented by a 38.22% maximum decrease in intraocular pressure vs. 31.14 and 21.99% decrease for the commercial Azopt^® eye drops and Cidamex^® tablets, respectively. It also exhibited higher (AUC_0–10) compared to Azopt^® eye drops and Cidamex^® tablets by 2.3 and 3 times, respectively. F5 showed mean residence time 4.22 h vs. 2.36 and 2.62 h for Azopt^® and Cidamex^® with no eye irritation observed according to the modified Draize test. To the best of our knowledge, this is the first study for developing acetazolamide-loaded cubosomes as the topical delivery system for glaucoma treatment.

Therapeutic Drugs and Devices for Tackling Ocular Hypertension and Glaucoma, and Need for Neuroprotection and Cytoprotective Therapies

Damage to the optic nerve and the death of associated retinal ganglion cells (RGCs) by elevated intraocular pressure (IOP), also known as glaucoma, is responsible for visual impairment and blindness in millions of people worldwide. The ocular hypertension (OHT) and the deleterious mechanical forces it exerts at the back of the eye, at the level of the optic nerve head/optic disc and lamina cribosa, is the only modifiable risk factor associated with glaucoma that can be treated. The elevated IOP occurs due to the inability of accumulated aqueous humor (AQH) to egress from the anterior chamber of the eye due to occlusion of the major outflow pathway, the trabecular meshwork (TM) and Schlemm’s canal (SC). Several different classes of pharmaceutical agents, surgical techniques and implantable devices have been developed to lower and control IOP. First-line drugs to promote AQH outflow via the uveoscleral outflow pathway include FP-receptor prostaglandin (PG) agonists (e.g., latanoprost, travoprost and tafluprost) and a novel non-PG EP2-receptor agonist (omidenepag isopropyl, Eybelis^®). TM/SC outflow enhancing drugs are also effective ocular hypotensive agents (e.g., rho kinase inhibitors like ripasudil and netarsudil; and latanoprostene bunod, a conjugate of a nitric oxide donor and latanoprost). One of the most effective anterior chamber AQH microshunt devices is the Preserflo^® microshunt which can lower IOP down to 10–13 mmHg. Other IOP-lowering drugs and devices on the horizon will be also discussed. Additionally, since elevated IOP is only one of many risk factors for development of glaucomatous optic neuropathy, a treatise of the role of inflammatory neurodegeneration of the optic nerve and retinal ganglion cells and appropriate neuroprotective strategies to mitigate this disease will also be reviewed and discussed.

Phase Transition Microemulsion of Brimonidine Tartrate for Glaucoma Therapy: Preparation, Characterization and Pharmacodynamic Study

Purpose: The aim of this study was to formulate brimonidine tartrate loaded phase transition microemulsions (PMEs), which undergo phase transition from water in oil (W/O) microemulsions to liquid crystalline (LC) and then oil in water (O/W) microemulsions after instilled into the eye and prolong the precorneal residence time and ocular bioavailability for the effective treatment of glaucoma.Methods: The pseudo-ternary phase diagram was developed and various PMEs were prepared using Tween 80 and Span 80 with isopropyl myristate and water. Globule size and shape, physicochemical parameters, in vitro and ex vivo drug release of PMEs were studied. The in vivo anti-glaucoma efficacy of optimized PMEs was studied in an experimental rabbit eyes model and compared with marketed formulation (MF).Results: Globule size of PMEs was found less than 200 nm, which was confirmed by both dynamic light scattering technique and Transmission Electron Microscopy. Physicochemical properties such as pH, refractive index, percentage transparency, viscosity and conductivity were also found in the acceptable ranges. In vitro release studies of PMEs exhibited sustained release property. Ex vivo permeation study also supported the enhanced drug flux through cornea from PMEs as compared with MF. In pharmacodynamic study, a greater reduction in intraocular pressure was seen in PMEs as compared to MF.Conclusion: PMEs as ocular drug delivery system offer a promising approach to enhance the corneal contact, higher permeation and prolonged precorneal retention time in the eye leading to sustained drug release, enhanced bioavailability and patient compliance.

Optimization and Characterization of Brimonidine Tartrate Nanoparticles-loaded In Situ Gel for the Treatment of Glaucoma

Purposes: The present study aimed to develop brimonidine tartrate loaded poly(lactic-co-glycolic acid) acid vitamin E-tocopheryl polyethylene glycol 1000 succinate (BRT-PLGA-TPGS) nanoparticles in thermosensitivein situ gel to improve mucoadhensive properties and drug holding capacity for the better management of glaucoma.Methods: Nanoparticles was optimized by means of Box-Behnken Design (BBD). The formulations were prepared using various concentration of PLGA (0.1-0.4% w/v) and TPGS (0.3-0.5% w/v). The analytical data of fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) depicted the drug excipients compatibility and confirmed the nanoparticles. Nanoparticles incorporated gel was evaluated for transcorneal permeability, gelation time, gelling temperature, and rheological studies. In addition, in vitro, transcorneal permeation drug release studies and intraocular pressure (IOP) for optimized gel was also performed. Biocompatibility of formulations was investigated in rabbit model.Results: The drug loaded nanoparticles exhibited 115.72 ± 4.18 nm, 0.190 ± 0.02, -11.80 ± 2.24 mV and 74.85 ± 6.54% of mean size, polydispersity index (PDI), zeta potential and entrapment efficiency (% EE), respectively. As compared to marketed eye drop, the sustained and continuous release BRT release from Poloxamer-based in situ gel was 85.31 ± 3.51% till 24 h. The transcorneal steady-state flux (136.32 μg cm^-2 h^-1) of optimized in situ gel was approximately 3.5 times higher than marketed formulation (38.60 μg cm^-2 h^-1) flux at 4 h. The optimized formulation produces 3 fold greater influences on percentage reduction of IOP (34.46 ± 4.21%) than the marketed formulation (12.24 ± 2.90%) till 8 h.Conclusion: The incorporation of optimized BRT-PLGA-TPGS nanoparticles into a thermosensitivein situ gel matrix to improve precorneal residence time without causing eye irritation and also serve the sustained release of BRT through cornea for effective management of glaucoma.

Investigational Agents in Development for the Treatment of Geographic Atrophy Secondary to Age-Related Macular Degeneration

Geographic atrophy (GA) is an advanced form of age-related macular degeneration, a late-onset, complex, genetic degenerative disease of the retina. Multiple environmental and genetic factors have been implicated in the development of GA, a pathology ultimately defined by loss of photoreceptors and the underlying retinal pigment epithelium and choriocapillaris. The personal burden of GA has been documented to have a substantial negative impact on quality of life, with progressive and cumulative loss of visual function each year. Currently, there are no treatments to prevent or slow the development or progression of GA. Multiple genetic and histopathologic studies have implicated dysregulation of the complement cascade in GA pathogenesis, leading to the development of several investigational pharmaceuticals targeting key factors in this inflammatory pathway. Several other biochemical pathways have also been implicated in GA development and progression, such as mitochondrial components, mediators of apoptosis and molecules involved in extracellular matrix remodeling, many of which are also being investigated for their potential value as therapeutic targets for GA treatment. Recent advancements in our understanding of GA pathogenesis and the progression of multiple potential therapeutics into later-stage human clinical trials hold great promise for a clinically effective therapeutic for patients with GA to emerge within the near future.

A longitudinal comparison in cynomolgus macaques of the effect of brimonidine on optic nerve neuropathy using diffusion tensor imaging magnetic resonance imaging and spectral domain optical coherence tomography

Early detection of optic neuropathy is crucial for initiating treatment that could delay or prevent visual field loss. Preclinical studies have advanced a number of potential neuroprotective strategies to prevent retinal ganglion cell (RGC) degeneration, but none have successfully completed clinical trials. One issue related to the lack of preclinical to clinical translation is the lack of preclinical morphometric assessments that could be used to track neuroprotection, as well as neurodegeneration, over time within the same animal. Thus, to assess whether clinically used morphometric assessments can identify neuroprotection of RGC, the current study compared optic nerve fractional anisotropy (FA) obtained with diffusion tensor imaging (DTI) and retinal nerve fiber layer (RNFL) thickness measured with spectral domain optical coherence tomography (SD-OCT) to observe not only the early progression of RGC axonal degeneration but to also discern which imaging modality identifies signs of neuroprotection during treatment with the alpha-adrenoceptor agonist brimonidine. Elevated and sustained intraocular pressure (IOP) was observed following laser photocoagulation of the trabecular meshwork in one eye of nonhuman primates (NHP). Either brimonidine (0.1%) or control treatment was instilled twice daily for two months. In control-treated eyes, increased IOP, increased vertical cup-to-disc (C/D), reduced rim-to-disc (R/D) ratio, decreased RNFL thickness and decreased FA were observed. While IOP remained elevated during the course of the study, brimonidine tended to delay the progression of RNFL thinning. However, in the same animal, optic nerve FA did not appear to decline. Brimonidine treatment did not affect other measures of RGC axonal degeneration. The current findings demonstrate that early progression of optic neuropathy can be tracked over time in a nonhuman primate model of ocular hypertension using either DTI or SD-OCT. Furthermore, the delayed changes to RNFL thickness and FA appear to be a neuroprotective effect of brimonidine independent of its effect on IOP.

The effect of brimonidine and proparacaine on metabolic enzymes: Glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glutathione reductase

Oxidative stress is to upregulate the pentose phosphate pathway (PPP). The PPP consists of two functional branches, glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconaste dehydrogenase (6PGD). Glutathione reductase (GR) has a significant role in catalyzing an oxidized glutathione form into a reduced form. The purpose of this study is to investigate the effects of brimonidine and proparacaine on the activity of 6PGD, G6PD, and GR enzymes purified from human erythrocytes. Brimonidine displayed considerable inhibition profile against G6PD with IC₅₀ value and K_I constant of 29.93 ± 3.56 and 48.46 ± 0.66 μM, respectively. On the other hand, proparacaine had no inhibitory effect against G6PD. K_I values were found to be 66.06 ± 0.78 and 811.50 ± 11.13 μM for brimonidine and proparacaine, respectively, for 6PGD. K_I values were found to be 144.10 ± 2.01 and 1,654.00 ± 26.29 μM for brimonidine and proparacaine, respectively, for GR. Herein, also in silico molecular docking studies were performed between drugs and enzymes.

The Latest Drugs in Development That Reduce Intraocular Pressure in Ocular Hypertension and Glaucoma

Glaucoma causes irreversible vision loss, with elevated intraocular pressure (IOP) being the only known modifiable risk factor. There are a variety of medical and interventional options for lowering IOP; however, despite these treatments, glaucoma continues to be a leading cause of visual impairment. Further research continues to strive for treatment options with improved side effect profiles, additional IOP-lowering effects, and ease of use. This review provides a brief summary of current IOP-lowering therapies and then outlines pipeline ocular hypotensive agents, their mechanisms of action, benefits, and side effect profiles. Advancements are seen within currently used eye drop classes such as prostaglandin analogues, Rho kinase inhibitors and nitric oxide donors, whilst there are also new drug classes, such as tyrosine protein kinase activators. Most developing drugs are topical drop formulations, with a number already having entered Phase III trials. Alternative drug delivery methods are also in development and will be briefly discussed. Pharmacological and drug delivery developments continue to provide glaucoma patients and clinicians with new options and the promise of better outcomes, particularly in terms of improved tolerance and reduced frequency of dosing.

Time-course of the visual Impact on presbyopes of a low dose miotic

PURPOSE

To examine the pupil and visual impact of a single early morning drop of a low concentration miotic.

METHODS

Pupil size, refraction, visual acuity (VA), near reading performance and intraocular pressure were monitored for 8 h at a wide range of light levels following bilateral instillation of single drops of 0.1% brimonidine tartate in 19 early presbyopes (40-50 years) and 11 mature presbyopes (>50 years).

RESULTS

Pupil miosis did not alter distance VA or refraction. Significant pupil miosis peaked at 1-2 h after dosing, which expanded the depth of focus of mature presbyopes with the mean improvement in near logMAR VA of -0.15, -0.07 and -0.03, at 20, 200 and 2000 lux, respectively. One hour after instillation, near reading speed improved by 21, 24 and 5 words per min for text size commonly seen in US newspaper and cellphone text messages, 18, 21 and 19 words per min for text size of grocery labels and 12, 13 and 30 words per min for text size of over-the-counter medications at light levels of 20, 200 and 2000 lux, respectively. No such improvements in near VA and near reading speed were observed in the young presbyopes having some residual accommodation. Most of the pupil miosis remained 8 h after instillation, whereas near VA improvements disappeared after 4 h.

CONCLUSION

Low dose miotics can enhance near vision in presbyopic subjects while retaining high quality distance vision over a wide range of light levels. Significant improvements in near vision were observed only during the 1-2 h period after dosing when miosis peaked.

Effects of primary glaucoma on sleep quality and daytime sleepiness of patients residing at an equatorial latitude

AIM

To investigate the impact of primary glaucoma on sleep quality and daytime sleepiness of patients.

METHODS

Prospective cross-sectional study with consecutive sampling in South-East Asian population was performed. Validated questionnaires: the Pittsburg Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS) were administered prospectively. Subjects with non-glaucomatous optic neuropathy or concomitant retinal pathology were excluded. Glaucoma severity was based on HVF 24-2 perimetry. Binocular single vision was represented based on the better eye. Frequency of and predictive factors for poor sleep quality and excessive daytime sleepiness were compared.

RESULTS

A total of 79 primary open angle glaucoma (POAG), 27 primary angle-closure glaucoma (PACG) patients, and 89 controls were recruited. PACG patients had higher median PSQI scores (P=0.004) and poorer sleep quality (P<0.001). Compared to controls, PACG patients were 3.34 times more likely to have poor sleep quality (P=0.008), which remained significant after adjustment for demographics (P=0.016) and predictive variables (P=0.013). PACG patients have poorer sleep quality when visual acuity (VA) was 6/15 or worse (P=0.009). Univariate and multivariate analysis of predictive variables for poor sleep quality and daytime sleepiness did not find statistical significance.

CONCLUSION

PACG patients have poorer sleep quality but not daytime sleepiness. This is important in South-East Asian population with heavy disease burden. Evaluations on sleep disturbances can be considered to provide more holistic care.

Gelling hypotonic polymer solution for extended topical drug delivery to the eye

Eye-drop formulations should hold as high a concentration of soluble drug in contact with ocular epithelium for as long as possible. However, eye tears and frequent blinking limit drug retention on the ocular surface, and gelling drops typically form clumps that blur vision. Here, we describe a gelling hypotonic solution containing a low concentration of a thermosensitive triblock copolymer, for extended ocular drug delivery. On topical application, the hypotonic formulation forms a highly uniform and clear thin layer that conforms to the ocular surface and resists clearance from blinking, significantly increasing the intraocular absorption of hydrophilic and hydrophobic drugs and extending the drug–ocular-epithelium contact time with respect to conventional thermosensitive gelling formulations and commercial eye drops. We also show that the conformal gel layer allows for therapeutically relevant drug delivery to the eyeball’s posterior segment in pigs. Our findings highlight the importance of formulations that conform to the ocular surface prior to viscosity enhancement, for increased and prolonged ocular-surface contact and drug absorption.

Evidence on the neuroprotective properties of brimonidine in glaucoma

BACKGROUND

glaucoma is the leading cause of irreversible blindness all over the world. The degree of visual field loss accounts for the severity of the disease and represents the main clinical outcome of treatment for patients affected by glaucoma. The α2 agonists, like brimonidine, emerged in the 1960s as topical ophthalmologic treatment. Their neuroprotective mechanism in glaucoma is still debated, ranging from effect on extracellular glutamate, to ocular hypotension and blood flow.

OBJECTIVES

this systematic review and meta-analysis aims at assessing the efficacy of brimonidine on visual field deterioration during glaucoma through the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) approach. Databases consulted: the literature search has been performed on PubMed, MEDLINE, ClinicalTrials.gov and Scopus up to June 10th, 2020. Study eligibility criteria, participants, and interventions: clinical trials assessing the effects of brimonidine on visual field in patients with glaucoma. Study appraisal: the eligibility of the studies has been assessed by two independent authors and the selection has followed the PRISMA flow diagram. The retrieved results have been subjected to risk of bias evaluation.

RESULTS

the search of literature has retrieved 418 papers, among which 5 are eligible for inclusion in the qualitative analysis. All the studies present high heterogeneity, therefore meta-analysis has not been possible. The results obtained suggest that brimonidine improves visual field, but the design of the clinical trials rises some concerns in terms of risk of bias.

CONCLUSIONS

the evidence of neuroprotective effect of brimonidine is inconclusive and needs stronger support. Large double-blind randomized clinical trials are necessary to strengthen this evidence.

Prolonged central nervous system and respiratory depression in preterm neonates after exposure to brimonidine tartrate and timolol maleate ophthalmic drops

Objective: We report three cases of preterm neonates who presented with central nervous system (CNS) and respiratory depression after inadvertent exposure to brimonidine tartrate 0.2% and timolol maleate 0.5% fixed-combination ophthalmic drops. Case descriptions: CNS and respiratory depression were observed in the three neonates within two hours of administration of brimonidine tartrate 0.2% and timolol maleate 0.5% eye drops. Respiratory support was initiated upon admission to the neonatal intensive care unit (NICU). The effects of the drug combination lasted for 24 to 48 hours. Conclusion: This case series suggests that the drug combination of brimonidine tartrate and timolol maleate causes a prolonged depression of the central nervous and respiratory systems in preterm neonates.

Rare protein-altering variants in ANGPTL7 lower intraocular pressure and protect against glaucoma

Protein-altering variants that are protective against human disease provide in vivo validation of therapeutic targets. Here we use genotyping data from UK Biobank (n = 337,151 unrelated White British individuals) and FinnGen (n = 176,899) to conduct a search for protein-altering variants conferring lower intraocular pressure (IOP) and protection against glaucoma. Through rare protein-altering variant association analysis, we find a missense variant in ANGPTL7 in UK Biobank (rs28991009, p.Gln175His, MAF = 0.8%, genotyped in 82,253 individuals with measured IOP and an independent set of 4,238 glaucoma patients and 250,660 controls) that significantly lowers IOP (β = -0.53 and -0.67 mmHg for heterozygotes, -3.40 and -2.37 mmHg for homozygotes, P = 5.96 x 10-9 and 1.07 x 10-13 for corneal compensated and Goldman-correlated IOP, respectively) and is associated with 34% reduced risk of glaucoma (P = 0.0062). In FinnGen, we identify an ANGPTL7 missense variant at a greater than 50-fold increased frequency in Finland compared with other populations (rs147660927, p.Arg220Cys, MAF Finland = 4.3%), which was genotyped in 6,537 glaucoma patients and 170,362 controls and is associated with a 29% lower glaucoma risk (P = 1.9 x 10-12 for all glaucoma types and also protection against its subtypes including exfoliation, primary open-angle, and primary angle-closure). We further find three rarer variants in UK Biobank, including a protein-truncating variant, which confer a strong composite lowering of IOP (P = 0.0012 and 0.24 for Goldman-correlated and corneal compensated IOP, respectively), suggesting the protective mechanism likely resides in the loss of interaction or function. Our results support inhibition or down-regulation of ANGPTL7 as a therapeutic strategy for glaucoma.

A review of neuropsychiatric adverse events from topical ophthalmic brimonidine

Brimonidine is a first-line topical medication for increased intraocular pressure and glaucoma which may be used alone or in conjunction with other topical therapies. Its structural and pharmacological comparabilities to clonidine give way to the hypothesis that it may cause neuropsychiatric side effects. The majority of case reports citing brimonidine toxicity, either for topical or peripheral exposure, include pediatric age groups but especially infants. Among the latter, a dose-response phenomenon is evident. Dose-response correlates have also been shown among adults. Case series and prospective double-blind treatment studies also give evidence for the occurrence of several central nervous system adverse reactions. Topical ophthalmic brimonidine use should be followed for the occurrence of neuropsychiatric disturbances generally, and enhanced vigilance should be maintained for at-risk populations.

Fixed-combination topical anti-hypertensive ophthalmic agents

INTRODUCTION

Fixed-combination glaucoma medications have altered the paradigm of ocular hypertension and glaucoma treatment and are in widespread use today. A comprehensive review of fixed-combination medications will help educate and inform providers for optimal patient care.

AREAS COVERED

In this review, the authors describe the composition, mechanism of action, efficacy, side effects, and safety profile of fixed-combination agents for the treatment of ocular hypertension and glaucoma as well as comparisons between the most frequently prescribed medications.

EXPERT OPINION

Fixed-combination therapeutics provide an effective and efficient means of lowering intraocular pressure with comparable side effects and outcomes to constituent parts with lower patient exposure to preservatives and improvement in compliance.

Neuroprotective Strategies for Retinal Ganglion Cell Degeneration: Current Status and Challenges Ahead

The retinal ganglion cells (RGCs) are the output cells of the retina into the brain. In mammals, these cells are not able to regenerate their axons after optic nerve injury, leaving the patients with optic neuropathies with permanent visual loss. An effective RGCs-directed therapy could provide a beneficial effect to prevent the progression of the disease. Axonal injury leads to the functional loss of RGCs and subsequently induces neuronal death, and axonal regeneration would be essential to restore the neuronal connectivity, and to reestablish the function of the visual system. The manipulation of several intrinsic and extrinsic factors has been proposed in order to stimulate axonal regeneration and functional repairing of axonal connections in the visual pathway. However, there is a missing point in the process since, until now, there is no therapeutic strategy directed to promote axonal regeneration of RGCs as a therapeutic approach for optic neuropathies.

Effect of Ultra-Small Chitosan Nanoparticles Doped with Brimonidine on the Ultra-Structure of the Trabecular Meshwork of Glaucoma Patients

Brimonidine, an anti-glaucoma medicine, acts as an adrenergic agonist which decreases the synthesis of aqueous humour and increases the amount of drainage through Schlemm's canal and trabecular meshwork, but shows dose-dependent (0.2% solution thrice daily) toxicity. To reduce the side effects and improve the efficacy, brimonidine was nanoencapsulated on ultra-small-sized chitosan nanoparticles (nanobrimonidine) (28 ± 4 nm) with 39% encapsulation efficiency, monodispersity, freeze-thawing capability, storage stability, and 2% drug loading capacity. This nanocomplex showed burst, half, and complete release at 0.5, 45, and 100 h, respectively. Nanobrimonidine did not show any in vitro toxicity and was taken up by caveolae-mediated endocytosis. The nanobrimonidine-treated trabeculectomy tissue of glaucoma patients showed better dilation of the trabecular meshwork under the electron microscope. This is direct evidence for better bioavailability of nanobrimonidine after topical administration. Thus, the developed nanobrimonidine has the potential to improve the efficacy, reduce dosage and frequency, and improve delivery to the anterior chamber of the eye.

Evaluating Glaucoma Treatment Effect on Intraocular Pressure Reduction Using Propensity Score Weighted Regression

Observational studies in glaucoma patients can provide important evidence on treatment effects, especially for combination therapies which are often used in reality. But the success relies on the reduction of selection bias through methods such as propensity score (PS) weighting. The objective of this study was to assess the effects of five glaucoma treatments (medication, laser, non-laser surgery (NLS), laser + medication, and NLS + medication) on 1-year intraocular pressure (IOP) change. Data were collected from 90 glaucoma subjects who underwent a single laser, or NLS intervention, and/or took the same medication for at least 6 months, and had IOP measures before the treatment and 12-months after. Baseline IOP was significantly different across groups (p = 0.007) and this unbalance was successfully corrected by the PS weighting (p = 0.81). All groups showed statistically significant PS-weighted IOP reductions, with the largest reduction in NLS group (-6.78 mmHg). Baseline IOP significantly interacted with treatments (p = 0.03), and at high baseline IOP medication was less effective than other treatments. Our findings showed that the 1-year IOP reduction differed across treatment groups and was dependent on baseline IOP. The use of PS-weighted methods reduced treatment selection bias at baseline and allowed valid assessment of the treatment effect in an observational study.

Dry Eye Symptoms and Ocular Pain in Veterans with Glaucoma

Dry eye and glaucoma are two frequently encountered ocular conditions, which can lead to substantial morbidity and decreased quality of life. Patients on topical glaucoma medications are known to be at greater risk for ocular surface symptoms. Veterans seen in the eye clinics at the Miami Veterans Affairs Hospital from January to July 2016 completed surveys assessing dry eye and ocular pain symptoms, including the five item Dry Eye Questionnaire (DEQ5). A total of 62 patients with glaucoma completed the survey. Of those, 52 were on glaucoma medications at the time of the survey, with the majority requiring more than one medication to control intraocular pressure. The frequency of mild or greater dry eye symptoms (defined as DEQ5 >6) tended to increase with increasing medication burden, and patients on brimonidine were more likely to report a DEQ5 >6. Patients on three or more glaucoma medications were more likely to report symptoms of shooting pain, dryness, and itchiness. Patients using timolol were more likely to report throbbing and pain by light, while those on latanoprost reported stinging. Our data support an association between increasing number of glaucoma medications and worsening of dry eye symptoms. Patient and medication-associated symptoms can be used to tailor individual medication regimens.

Effects of the Glaucoma Drugs Latanoprost and Brimonidine on Corneal Temperature

Purpose

The aim of this study was to investigate the effects of the glaucoma drugs latanoprost, brimonidine, and the combination of both on the central corneal temperature (CT) of healthy subjects by means of infrared thermography. Changes of the central CT may reflect changes of ocular blood flow.

Methods

Before application and during 2 hours after the application of latanoprost, brimonidine, or the combination of both in one eye, the CT in both eyes of 40 healthy subjects was measured repeatedly.

Results

Brimonidine reduced CT by approximately 0.5°C. This effect was statistically significant (P < 0.0001). Latanoprost, however, had a very small and insignificant influence (P = 0.47). Accordingly, the combination of brimonidine and latanoprost also reduced CT up to 0.5°C, and this effect was statistically significant (P < 0.0001).

Conclusions

Brimonidine, but not latanoprost, had a significant effect on central CT. This cooling effect of brimonidine is most probably due to a drug-induced reduction of blood circulation in the ciliary body and iris and to a certain extent also to a reduction of blood flow in the fundus of the eye.

Translational Relevance

This study shows evidence that thermography of the cornea provides indirect information on the influence of drugs on the blood flow to the anterior segment of the patient's eye.

Effects of Brimonidine and Timolol on the Progression of Visual Field Defects in Open-angle Glaucoma: A Single-center Randomized Trial

PRéCIS:: Instillation of brimonidine or timolol slowed visual field deterioration in patients with open-angle glaucoma; both brimonidine and timolol might improve the mean deviation (MD) slopes.

PURPOSE

The purpose of this study was to investigate and compare the effects of 0.1% brimonidine and 0.5% timolol on the progressing visual field defects in open-angle glaucoma.

PATIENTS AND METHODS

We evaluated 1 eye each of 68 glaucoma patients who were treated with at least 1 prostaglandin analog. Their baseline MD slopes were < -0.5 dB/y based on at least 5 Humphrey field analyzer measurements within 3 years. Eligible eyes were randomly assigned to brimonidine or timolol treatment groups and treatments were administered without the wash-out period. Clinical examinations were performed every 4 months for 2 years. We designated the MD slope as the primary endpoint.

RESULTS

Ultimately, 56 eyes (brimonidine:timolol=26:30) were included in the present study (mean age=65.2 y). Dropout rates of brimonidine and timolol treatment groups were 27.8% and 6.3%, respectively. There were no significant differences in baseline intraocular pressure or MD slopes between brimonidine and timolol groups (12.7 and 12.9 mm Hg, P=0.77, and -1.22 and -1.08 dB/y, P=0.43, respectively). Intraocular pressure decreased significantly in the brimonidine group at 4, 8, 12, and 16 months, and in the timolol group at 4 months, without significant differences between the drugs (P=0.20). MD slopes significantly improved in both groups (brimonidine: -0.38 dB/y, P<0.001; timolol: -0.52 dB/y, P=0.04). Furthermore, there was no significant difference between groups in the primary endpoint (P=0.59).

CONCLUSION

Brimonidine and timolol treatments improved MD slopes in open-angle glaucoma.

[Selective α2-agonists in the treatment of glaucoma: pharmacology, efficacy and safety]

Glaucoma is the main cause of irreversible blindness in the world. Among the hypotensive eye drops, an important place belongs to the selective α2-adrenergic receptor antagonist brimonidine. This part of the review focuses on key pharmacological and therapeutic characteristics of brimonidine and its mode of action. The article also discusses the side effects of brimonidine and the methods of their prevention.

Efficacy of three different formulations of brimonidine for control of intraocular pressure in primary open-angle glaucoma: A 6-week randomized trial

BACKGROUND:

To compare the intraocular pressure (IOP)-lowering efficacy and safety of brimonidine (0.2%), brimonidine purite (0.15%), and brimonidine purite (0.1%) in patients of primary open-angle glaucoma (POAG).

MATERIALS AND METHODS:

Sixty patients of POAG with IOP >21 mmHg were enrolled into this study for 6-week duration. The patients were randomly divided into three groups with 20 patients in each group. Group A instilled brimonidine 0.2%, Group B instilled brimonidine purite 0.15%, and Group C instilled brimonidine purite 0.1% twice daily. IOP was recorded by applanation tonometry at baseline and subsequently at 2, 4, and 6 weeks at 9:00–10:00 am during each visit around 30 min after instillation of eye drops.

RESULTS:

Mean IOP reduction in Group A was from 25.55 ± 2.01 to 19.85 ± 2.05 mmHg at the end of study, thus resulting in fall of 5.70 mmHg (22.30%), in Group B, it decreased from 25.65 ± 2.41 to 19.55 ± 2.43 mmHg, thus resulting in fall of 6.10 mmHg (23.78%), and in Group C, it decreased from 25.80 ± 2.26 mmHg to 19.85 ± 2.16 mmHg, thus resulting in fall of 6.35 mmHg (24.61%). There was no statistically significant difference in IOP-lowering efficacy of study drugs. Conjunctival hyperemia, foreign body sensation, dry eye, and papillary reaction were the important side effects seen with study drugs. Brimonidine 0.2% caused more side effects than brimonidine purite 0.15% and brimonidine purite 0.1%.

CONCLUSION:

All the three formulations of brimonidine produced statistically equal lowering of IOP in patients of POAG with reduced systemic and ocular adverse reactions with brimonidine purite 0.15% and 0.1%.

Formulation and ex vivo-in vivo evaluation of pH-triggered brimonidine tartrate in situ gel for the glaucoma treatment using application of 32 factorial design

CONTEXT

Short residence time, poor bioavailability and poor permeability are the major problems for conventional eye drops treatment.

OBJECTIVE

The aim of this article is to develop, optimize and ex vivo-in vivo investigation of brimonidine tartrate in situ gel as compared to marketed eye drops for the treatment of glaucoma.

MATERIALS AND METHODS

The effect of independent variables, namely concentrations of polymers, on various dependent variables like viscosity at physiological pH and in vitro drug release were studied by using 3² factorial design. Further the optimized formulation was characterized for ex vivo and in vivo study.

RESULTS AND DISCUSSION

Experimental data demonstrated that optimized in situ gel formulation (F8) showed in vitro-ex vivo sustained release profile with polymer composites carbopol 974P and HPMC K4M. After 5 h of ex vivo transcorneal permeation study, the amount recovered from the corneal surface on the donor chamber 12.40% (124 ug) and the amount collected from the receptor chamber 76.8% (760 ug) of the initial dose 1 mg. The total amount recovered from the permeation experiment was 89.2%. Bioadhesive carbopol 974P and viscosity HPMC K4M composites optimized formulation (F 8) produce greater influence on the duration of drug action and improved intraocular pressure reduction activity as compared to marketed eye drop solution in in vivo study.

CONCLUSION

The developed in situ gelling system as a promising ophthalmic formulation to prolong the drug lowering effect on the intraocular pressure.

Application of Imaging Mass Spectrometry to Assess Ocular Drug Transit

Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) is becoming an important technology to determine the distribution of drugs and their metabolites in the tissue of preclinical species after dosing. Interest in IMS is growing in the ophthalmology field, but little work to this point has been done to investigate ocular drug transit using this technology. Information on where and how a drug is distributing through the eye is important in understanding efficacy and whether it is reaching the desired target tissue. For this study, ocular distribution of brimonidine was investigated in rabbits following topical administration. Brimonidine has been shown to lower intraocular pressure and is approved to treat glaucoma, the second leading cause of blindness in the world. We have developed IMS methods to assess transit of topically administered brimonidine from the anterior to the posterior segment of rabbit eyes. Using IMS, brimonidine was detected in the cornea, aqueous humor, iris, and posterior segments of the eye. The distribution of brimonidine suggests that the route of transit following topical administration is mainly through the uvea-scleral route. This study demonstrates that IMS can be applied to assess ocular transit and distribution of topically administered drugs.

A validated stability-indicating HPLC method for determination of brimonidine tartrate in BRI/PHEMA drug delivery systems

BACKGROUND

A simple, rapid and accurate stability-indicating reverse phase high performance liquid chromatography (RP-HPLC) was developed and validated for the determination of brimonidine tartrate in brimonidine tartrate/poly(2-hydroxyethyl methacrylate) (BRI/PHEMA) drug delivery contact lenses and pharmaceutical formulations.

RESULTS

Optimum chromatographic conditions for separating brimonidine tartrate from other impurities in the leaching liquor of BRI/PHEMA drug delivery contact lenses or pharmaceutical formulations have been achieved by using a Diamonsil C18 column (150 mm × 4.6 mm, 5 μm) as a stationary phase and a mixture solution of phosphate buffer (10 mM, pH3.5) containing 0.5% triethlamine and methanol (85:15, v/v) as a mobile phase at a flow rate of 1 mL/min. The theoretical plates for the brimonidine tartrate measurement were calculated to be 8360 when detection was performed at 246 nm using a diode array detector. The proposed method was validated in accordance with ICH guidelines with respect to linearity, accuracy, precision, robustness, specificity, limit of detection and quantitation. Regression analysis showed a good correlation (R² > 0.999) for brimonidine tartrate in the concentration range of 0.01-50 μg/mL. The peak purity factor is ≥980 for the analyte after all types of stress tests, indicating an excellent separation of brimonidine tartrate peak from other impurities. The measurement course could be completed within 10 min, which was very quick, effective and convenient.

CONCLUSIONS

Overall, the proposed stability-indicating method was suitable for routine quality control and drug analysis of brimonidine tartrate in BRI/PHEMA drug delivery contact lenses and other pharmaceutical formulations.

Clinical outcomes of combined versus separate carbachol and brimonidine drops in correcting presbyopia

Background

To test and compare in a masked fashion the efficacy of using a parasympathomimetic drug (3% carbachol) and an alpha-2 agonist (0.2% brimonidine) in both combined and separate forms to create optically beneficial miosis to pharmacologically improve vision in presbyopia.

Methods

A prospective, double-masked, randomized, controlled clinical trial was conducted. Ten naturally emmetropic and presbyopic subjects between 42 and 58 years old with uncorrected distance visual acuity of at least 20/20 in both eyes without additional ocular pathology were eligible for inclusion. All subjects received 3% carbachol and 0.2% brimonidine in both combined and separate forms, 3% carbachol alone and 0.2% brimonidine (control) alone in their non-dominant eye in a crossover manner with one week washout between tests. The subjects’ pupil sizes and both near and distance visual acuities will be evaluated pre- and post-treatment at 1, 2, 4, and 8 h, by a masked examiner at the same room illumination.

Results

Statistically significant improvement in mean near visual acuity (NVA) was achieved in all subjects who received combined 3% carbachol and 0.2% brimonidine in the same formula compared with those who received separate forms or carbachol alone or brimonidine alone (P < 0.0001).

Conclusion

Based on the data, the combined solution demonstrated greater efficacy than the other solutions that were tested. Improving the depth of focus by making the pupil small caused statistically significant improvement in near visual acuity, with no change in binocular distance vision.

Trial registration

ACTRN12616001565437. Registered 11 November 2016.

Management of glaucoma in pregnancy: risks or choices, a dilemma?

The treatment of glaucoma in and around pregnancy offers the unique challenge of balancing the risk of vision loss to the mother as against the potential harm to the fetus or newborn. Most anti-glaucoma drugs (i.e. beta-blockers, prostaglandin analogues, carbonic anhydrase inhibitors topical and systemic, cholinergics, anticholinesterases, and apraclonidine) are considered category C agents and ophthalmologists are usually limited to treating patients with the category B drugs of brimonidine and dipivefrin. Brimonidine is generally the preferred first-line drug in the first, second and early third trimester. Late in the third trimester, brimonidine should be discontinued because it can induce central nervous system depression in newborns wherein topical carbonic anhydrase inhibitors may be the optimal choice. Glaucoma surgery can be performed with caution in second and third trimester if the patients have a strong indication for the procedure. However, anesthetics, sedative agents, and antimetabolites still have potential risk for the fetus. Argon laser trabeculoplasty (ALT) or selective laser trabeculoplasty (SLT) is an alternative treatment that can be performed in all trimesters. Carbonic anhydrase inhibitors and β-blockers are certified by the American Academy of Pediatrics for use during nursing. However, low doses of these medications should be considered when used in the breast feeding period. Optimum treatment for glaucoma in pregnancy must not be withheld so as to prevent any further deterioration in progressive vision loss and quality of life.

Clinical effectiveness of brinzolamide 1%-brimonidine 0.2% fixed combination for primary open-angle glaucoma and ocular hypertension

The main first-line treatment strategy for glaucoma is to reduce intraocular pressure (IOP) by topical ocular hypotensive medications, but many patients require multiple medications for adequate IOP control. Fixed-combination therapies provide several benefits, including simplified treatment regimens, theoretical improved treatment adherence, elimination of the potential for washout of the first drug by the second, and the reduction in ocular exposure to preservatives. β-Adrenoceptor antagonists (particularly 0.5% timolol) are the most commonly used agents in combination with other classes of drugs as fixed-combination eyedrops, but they are contraindicated in many patients, owing to local allergy or systemic side effects. A fixed-combination preparation without a β-blocker is therefore warranted. This paper reviews the clinical effectiveness of brinzolamide 1% and brimonidine 0.2% fixed combination (BBFC) for use in patients with primary open-angle glaucoma and ocular hypertension. We searched PubMed and the ClinicalTrials.gov registry, and identified three randomized controlled trials comparing BBFC vs its constituents (brimonidine vs brinzolamide), and one comparing BBFC with unfixed brimonidine and brinzolamide. All of the studies demonstrated mean diurnal IOP to be statistically significantly lower in the BBFC group compared with constituent groups and noninferior to that with the concomitant group using two separate bottles. The safety profile of BBFC was consistent with that of its individual components, the most common ocular adverse events being ocular hyperemia, visual disturbances, and ocular allergic reactions. Common systemic adverse effects included altered taste sensation, oral dryness, fatigue, somnolence, and decreased alertness. BBFC seems to be a promising new fixed combination for use in glaucoma patients. However, long-term effects of BBFC on IOP, treatment adherence, and safety need to be determined.

Natural Bioadhesive Biodegradable Nanoparticle-Based Topical Ophthalmic Formulations for Management of Glaucoma

PURPOSE

We prepared and characterized topical ophthalmic formulations containing brimonidine-loaded bioadhesive cationic chitosan or anionic alginate nanoparticles (NPs) for sustained release of brimonidine as once daily regimen for management of glaucoma.

METHODS

Nanoparticles were prepared using a spontaneous emulsification solvent diffusion method. Different concentrations of polymers, emulsifiers, and NPs stabilizers were used for formulation optimization. Nanoparticles were characterized regarding particle size, zeta potential, morphology, and drug content. Brimonidine-loaded NPs were incorporated into eye drops, a temperature-triggered in situ gelling system, and a preformed gel. They then were characterized regarding their pH, viscosity, uniformity of drug content, in vitro release characteristics, in vitro cytotoxicity, and in vivo intraocular pressure (IOP) lowering effects.

RESULTS

Characteristics of optimized brimonidine-loaded chitosan and alginate NPs, respectively, are: particle size, 115.67 ± 3.58 and 157.67 ± 5.53 nm; zeta potential, +35.27 ± 3.39 and -37.8 ± 3.77 mV; encapsulation efficiency, 74.34% ± 2.05% and 70.40% ± 2.77%; drug loading, 11.81% ± 0.67% and 13.14% ± 0.90%; and yield, 87.91% ± 5.92% and 76.53% ± 3.32%. Transmission electron microscope (TEM) analyses revealed that NPs have spherical shapes with a dense core and distinct coat. Formulations possessed uniform drug content. Furthermore, pH and viscosity were compatible with the eye. Formulations showed a sustained release without any burst effect with a Higuchi non-Fickian diffusion mechanism. Cytotoxicity studies revealed that all formulations are biocompatible. Importantly, all formulations possessed a sustained IOP lowering effect compared to the marketed brimonidine tartrate eye drops.

CONCLUSIONS

These formulations provide a great improvement in topical ocular brimonidine delivery. The application of a single drop is sufficient to provide extended IOP reduction, which should improve patient compliance.

TRANSLATIONAL RELEVANCE

We have developed a novel biocompatible topical delivery system for brimonidine, a first line glaucoma medication. Once daily application should have positive effects on patient compliance and, therefore, preservation of vision.

Biochemical changes and treatment in glaucoma

Glaucoma is the second cause of blindness worldwide. This disease is a neurodegenerative disorder characterized by high intraocular pressure, loss of retinal ganglion cells (apoptosis). Even though there is much research done in this field, the results have not yet managed to stop the progression of glaucoma or to heal this pathology. Free oxygen radicals play a major role; they are formed in the aqueous humor and in the vitreous and they produce apoptosis of the neurons in the optic nerve head, degradation of the trabecular meshwork cells. The purpose of the article is to help in trying to understand the physiopathology of glaucoma and the efficacy of its treatments.

Cumulative mtDNA damage and mutations contribute to the progressive loss of RGCs in a rat model of glaucoma

Glaucoma is a chronic neurodegenerative disease characterized by the progressive loss of retinal ganglion cells (RGCs). Mitochondrial DNA (mtDNA) alterations have been documented as a key component of many neurodegenerative disorders. However, whether mtDNA alterations contribute to the progressive loss of RGCs and the mechanism whereby this phenomenon could occur are poorly understood. We investigated mtDNA alterations in RGCs using a rat model of chronic intraocular hypertension and explored the mechanisms underlying progressive RGC loss. We demonstrate that the mtDNA damage and mutations triggered by intraocular pressure (IOP) elevation are initiating, crucial events in a cascade leading to progressive RGC loss. Damage to and mutation of mtDNA, mitochondrial dysfunction, reduced levels of mtDNA repair/replication enzymes, and elevated reactive oxygen species form a positive feedback loop that produces irreversible mtDNA damage and mutation and contributes to progressive RGC loss, which occurs even after a return to normal IOP. Furthermore, we demonstrate that mtDNA damage and mutations increase the vulnerability of RGCs to elevated IOP and glutamate levels, which are among the most common glaucoma insults. This study suggests that therapeutic approaches that target mtDNA maintenance and repair and that promote energy production may prevent the progressive death of RGCs.

The efficacy and safety of add-on 0.1% brimonidine tartrate preserved with sodium chlorite in on-treatment Japanese normal-tension glaucoma patients

Background

To evaluate the efficacy and safety of newly formulated brimonidine (0.1% brimonidine tartrate preserved with sodium chlorite: brimonidine) as add-on therapy in on-treatment Japanese normal-tension glaucoma (NTG) patients.

Methods

Brimonidine was added to on-treatment NTG patients with intraocular pressures (IOP) of between 13 mmHg and 16 mmHg after three consecutive IOP measurements. The time courses of IOP, conjunctival hyperemia, superficial punctate keratitis, and adverse events were examined at 4, 8, and 12 weeks after brimonidine instillation.

Results

Though 75 of 83 patients (31 males and 52 females; mean age: 63.4±11.6 years) completed the study, six patients discontinued because of side effects and two patients withdrew. The mean IOP after brimonidine addition at week 4 (12.6±1.8 mmHg, P<0.001), week 8 (12.4±1.7 mmHg, P<0.001), and week 12 (12.6±1.8 mmHg, P<0.001) was significantly decreased compared with that before the addition of brimonidine (13.9±1.2 mmHg). No significant changes in superficial punctate keratitis or conjunctival hyperemia scores were observed throughout the study. Dizziness, sleepiness, eye pain, and itching (mild to moderate) were noted in five, four, three, and three patients, respectively.

Conclusions

The addition of newly formulated brimonidine to on-treatment Japanese NTG patients with IOP of 13–16 mmHg further reduced the levels of IOP with minimal side effects and adverse events.