Pharmacotherapy of glaucoma

Many Faces of Renin-angiotensin System - Focus on Eye

The renin-angiotensin system (RAS), that is known for its role in the regulation of blood pressure as well as in fluid and electrolyte homeostasis, comprises dozens of angiotensin peptides and peptidases and at least six receptors. Six central components constitute the two main axes of the RAS cascade. Angiotensin (1-7), an angiotensin converting enzyme 2 and Mas receptor axis (ACE2-Ang(1-7)-MasR) counterbalances the harmful effects of the angiotensin II, angiotensin converting enzyme 1 and angiotensin II type 1 receptor axis (ACE1-AngII-AT1R) Whereas systemic RAS is an important factor in blood pressure regulation, tissue-specific regulatory system, responsible for long term regional changes, that has been found in various organs. In other words, RAS is not only endocrine but also complicated autocrine system. The human eye has its own intraocular RAS that is present e.g. in the structures involved in aqueous humor dynamics. Local RAS may thus be a target in the development of new anti-glaucomatous drugs. In this review, we first describe the systemic RAS cascade and then the local ocular RAS especially in the anterior part of the eye.

Seeing over the horizon - targeting the endocannabinoid system for the treatment of ocular disease

The observation that marijuana reduces intraocular pressure was made by Hepler and Frank in the 1970s. Since then, there has been a significant body of work investigating cannabinoids for their potential use as therapeutics. To date, no endocannabinoid system (ECS)-modulating drug has been approved for clinical use in the eye; however, recent advances in our understanding of the ECS, as well as new pharmacological tools, has renewed interest in the development of ocular ECS-based therapeutics. This review summarizes the current state-of-affairs for the use of ECS-modulating drugs for the treatment of glaucoma and ocular inflammatory and ischemic disease.

Impact of prostaglandin glaucoma drops on platelet-activating factor action: an in vitro study

AIM

The aim of this study was to investigate the effect of different prostaglandin analogs on platelet-activating factor (PAF) levels.

METHODS

Three prostaglandin analogs were selected: bimatoprost 0.3 mg/mL, latanoprost 50 μg/mL, and tafluprost 15 μg/mL. Each drug sample was tested for its ability to cause platelet aggregation, which was measured as PAF-induced aggregation, before and after the addition of various concentrations of the examined sample, creating a linear curve of percentage inhibition (ranging from 0% to 100%) versus different concentrations of the sample. The concentration of the sample that inhibited 50% PAF-induced aggregation was calculated based on this curve, and this value was defined as IC50. In addition, the effect of eye drops on PAF metabolism was examined, through an in vitro analysis on PAF basic metabolic enzymes (PAF-cholinephosphotransferase, PAF-acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine acetyltransferase, and PAF-acetylhydrolase).

RESULTS

The IC50 values for Lumigan UD^® (bimatoprost 0.3 mg/mL), Monoprost^® (latanoprost 50 μg/mL), and Saflutan (tafluprost 15 μg/mL) were 8.7, 0.28, and 1.4 μg/mL, respectively.

DISCUSSION

All three prostaglandin analogs suspended PAF, but bimatoprost induced the most potent inhibition, compared to tafluprost and to the weak effect of latanoprost.

Randomized, Controlled, Phase 3 Trials of Carteolol/Latanoprost Fixed Combination in Primary Open-Angle Glaucoma or Ocular Hypertension

PURPOSE

To assess the intraocular pressure (IOP)-lowering effects and safety of a carteolol/latanoprost fixed combination drug (OPC-1085EL) vs latanoprost (Study 1) and carteolol (Study 2) in patients with primary open-angle glaucoma (POAG) or ocular hypertension (OH).

DESIGN

Multicenter, randomized, evaluator-masked (Study 1)/double-masked (Study 2), parallel-group studies.

METHODS

Setting: Twenty-eight clinical sites (Study 1) and 19 clinical sites (Study 2) in Japan.

STUDY POPULATION

Outpatients with bilateral POAG or OH whose predose IOP was 18 to <35 mm Hg in the study eye after 4 weeks' treatment with latanoprost (Study 1) or carteolol (Study 2) (defined as baseline).

INTERVENTION

In Study 1, 237 patients applied OPC-1085EL (n = 118) or latanoprost (n = 119) for 8 weeks. In Study 2, 193 patients applied OPC-1085EL (n = 78), carteolol (n = 78), or carteolol/latanoprost concomitant therapy (n = 37) for 8 weeks.

MAIN OUTCOME MEASURE

Adjusted mean IOP reduction at predose from baseline to week 8.

RESULTS

In Study 1, the adjusted mean IOP reductions (95% confidence interval [CI]) were 2.9 (2.5-3.3) mm Hg and 1.6 (1.2-2.0) mm Hg in the OPC-1085EL and latanoprost groups, respectively (P < .0001). In Study 2, the adjusted mean IOP reductions (95% CI) were 3.5 (3.1-3.9) mm Hg and 1.6 (1.2-2.0) mm Hg in the OPC-1085EL and carteolol groups, respectively (P < .0001). All adverse drug reactions of OPC-1085EL observed in both studies were mild in severity and only 1 patient in each study discontinued because of an adverse drug reaction.

CONCLUSIONS

OPC-1085EL is superior to latanoprost or carteolol alone in terms of lowering IOP, and was well tolerated.

Long-term Safety and Efficacy of Latanoprostene Bunod 0.024% in Japanese Subjects with Open-Angle Glaucoma or Ocular Hypertension: The JUPITER Study

INTRODUCTION

Latanoprostene bunod (LBN) is a novel nitric oxide (NO)-donating prostaglandin F2α analog. We evaluated the long-term safety and intraocular pressure (IOP)-lowering efficacy of LBN ophthalmic solution 0.024% over 1 year in Japanese subjects with open-angle glaucoma (OAG) or ocular hypertension (OHT).

METHODS

This was a single-arm, multicenter, open-label, clinical study. Subjects aged 20 years and older with a diagnosis of OAG or OHT instilled 1 drop of LBN ophthalmic solution 0.024% in the affected eye(s) once daily in the evening for 52 weeks and were evaluated every 4 weeks. Safety assessments included vital signs, comprehensive ophthalmic exams, and treatment-emergent adverse events (AEs). Absolute and percent reductions from baseline in IOP were also determined.

RESULTS

Of 130 subjects enrolled, 121 (93.1%) completed the study. Mean age was 62.5 years, and mean (standard deviation) baseline IOP was 19.6 (2.9) and 18.7 (2.6) mmHg in study eyes and treated fellow eyes, respectively. Overall, 76/130 (58.5%) and 78/126 (61.9%) subjects experienced ≥1 AEs in study eyes and treated fellow eyes, respectively. In both study eyes and treated fellow eyes, the most common AEs were conjunctival hyperemia, growth of eyelashes, eye irritation, and eye pain. At 52 weeks, 9% of treated eyes had an increase in iris pigmentation compared with baseline based on iris photographs. No safety concerns emerged based on vital signs or other ocular assessments. Mean reductions from baseline in IOP of 22.0% and 19.5% were achieved by week 4 in study and treated fellow eyes, respectively. These reductions were maintained through week 52 (P < 0.001 vs. baseline at all visits).

CONCLUSION

Once daily LBN ophthalmic solution 0.024% was safe and well-tolerated in Japanese subjects with OAG or OHT when used for up to 1 year. Long-term treatment with LBN ophthalmic solution 0.024% provided significant and sustained IOP reduction.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT01895972.

FUNDING

Bausch & Lomb, Inc. a division of Valeant Pharmaceuticals International Inc.

Cardiac safety of ophthalmic timolol

INTRODUCTION

It is generally believed that topical administration of eye drops safeguards against harmful systemic effects. However, about 80% of the drug in the ophthalmic products is systemically absorbed and the first-pass metabolism is avoided. Ophthalmic timolol is widely prescribed in the treatment of glaucoma either alone or in the combination eye drop products, many of which have been launched fairly recently. Ophthalmic timolol may cause serious adverse effects such as symptomatic bradycardia, various conduction disorders in the heart, orthostatic hypotension, syncope and falls. Areas covered: In this review we document a number of factors associated with the properties of ophthalmic timolol and specific features of a patient, which may jeopardize patient's cardiac safety even after topical treatment. Expert opinion: Plasma timolol levels are correlated with cardiovascular adverse effects in patients, since timolol is mainly metabolized by cytochrome P450 2D6 (CYP2D6) enzyme in the liver. Patients who are lacking the functional CYP2D6 or who are concomitantly using potent CYP2D6 inhibitor drugs (e.g. paroxetine or fluoxetine) or verapamil or other beta-blockers are at risk of getting serious cardiac adverse effects. Prior to treatment initiation, ECG should be always performed and CYP2D6 genotyping should be considered, if routinely available.

Latanoprost and Dorzolamide for the Treatment of Pediatric Glaucoma: The Glaucoma Italian Pediatric Study (Gipsy), Design and Baseline Characteristics

Introduction

To investigate the efficacy of a treatment strategy with latanoprost and dorzolamide in primary pediatric glaucoma patients partially responsive to surgery.

Methods

Single arm, prospective, interventional multicenter study. Primary pediatric glaucoma patients younger than 13 years after a single surgical procedure with IOP between 22 and 26 mmHg were considered eligible. At baseline, patients were allocated to latanoprost monotherapy once daily. Depending on intraocular pressure (IOP) reduction at first visit, the patients were allocated to one of three groups: continuation of latanoprost monotherapy, addition of dorzolamide twice daily, or switch to dorzolamide three times daily. The same approach for allocation in medication groups was used in all subsequent visits. Patients in the dorzolamide monotherapy group with IOP reduction <20% from baseline were considered non-responders and withdrawn. Study treatment and patient follow-up will continue for 3 years or until treatment failure. The primary endpoint is the percentage of responders. Secondary endpoints are time to treatment failure and frequency of adverse events.

Results

A total of 37 patients (69 eyes) were enrolled. The mean age was 4.0 ± 3.8 years, the female/male ratio was 1/1.7, and the majority of patients were Caucasian. Eighty percent of patients had bilateral glaucoma. Goniotomy was the most frequently performed surgery (38.6%), followed by trabeculotomy (22.8%), trabeculectomy (21.1%), and trabeculectomy plus trabeculotomy (17.5%). The baseline IOP was 23.6 ± 1.5 mmHg.

Conclusion

The study population is representative of patients frequently encountered after the first surgery for primary pediatric glaucoma. The study will produce evidence on the medium-term efficacy of a defined pharmacological approach.

Anterior Chamber Angle Morphometry Measurement Changes to Ambient Illumination Scaling in Visante Time Domain Optical Coherence Tomography

PURPOSE

To test the effect of ambient illumination scaling on the reproducibility and reliability anterior chamber metrics using the Visante time domain optical coherence tomography (TD-OCT) instrument.

MATERIALS AND METHODS

The inferior irido-corneal angles of 25 normal, healthy eyes were imaged twice with the Zeiss Visante TD-OCT under five strictly controlled ambient light conditions (foot candles (fc) measured with a light meter at camera/eye interface). Each eye was imaged 10 times totaling 250 assessments. Angle opening distance (AOD500/750), trabecular iris space area (TISA500/750), and scleral spur (SS) angle were graded twice by masked, trained graders at the Doheny Imaging Reading Center using the Visante's intrinsic tools. Lighting effects on measurements, intra-/inter-grader and acquisition analyses, and Bland-Altman plots were computed using Statistical Package for Social Science (SPSS Inc. version 18.0, Armonk, NY).

RESULTS

With a near linear relationship of angle metrics to lights levels (R² = 0.8-0.95), the analysis examines the differences from the brightest to darkest light levels. Decreasing ambient light levels from 1.0 to 0.0 fc decreased the average AOD500 measurement from 407 ± 136 µm to 315 ± 114 µm (mean percent difference (MPD) 29%, p < 0.001), AOD750 from 587 ± 184 µm to 496 ± 155 µm (MPD 18%, p < 0.001), TISA500 from 136 ± 43 µm² to 101 ± 37 µm² (MPD 35%, p < 0.001), TISA750 from 269 ± 81 µm² to 212 ± 68 µm² (MPD 27%, p < 0.001), and SS angle from 38.3% ± 9% to 32.1% ± 9% (MPD 19%, p < 0.001). Intra-/inter-grader results showed good reproducibility for each grader (MPD = 0.7-3%; coefficient of variation (CV) = 3.2-8.3%; R² = 0.8-0.95; p < 0.001 for all metrics) and between graders (MPD = 1.4-5.9%; CV = 6.7-14.2%; R² = 0.81-0.89; Pearson Correlation Coefficient (PCC) = 0.8-0.97 (p<0.001)). Bland-Altman plots did not demonstrate any apparent bias, with similar repeatability and agreement.

CONCLUSIONS

The results of this study show the high sensitivity of the anterior chamber to changes in the illumination. The slight decrease in light had a corresponding large decrease in Anterior Chamber Angle (ACA) metrics. With clinical diagnoses and treatments of eye diseases relying on these angle measurements, these findings emphasize the importance of strictly controlling light conditions in order to obtain reproducible measurements of anterior chamber geometry.

Carbonic anhydrase inhibitors: a review on the progress of patent literature (2011-2016)

INTRODUCTION

A large area of carbonic anhydrase (CA) research focuses on the inhibition of human CA IX and CA XII, as these isoforms have been designated as biomarkers and therapeutic targets for various cancer types.

AREAS COVERED

Recently, the majority of CA inhibitor (CAI) patents cover compound design, synthesis, and delivery methods for the treatment of glaucoma and cancer. The analysis of included patents highlights the need for isoform specific inhibitors. This review covers the patents of medically relevant carbonic anhydrase inhibitors between 2011-2016.

EXPERT OPINION

The improvement of structure-based drug design methods and access to the crystal structures of human CA isoforms have improved inhibitor development. This progress can be observed in relation to the selective inhibition of CA IX for cancer treatments, with one inhibitor in clinical trials. However, the design of nonclassical CAIs is essential to further improve isoform specificity and prevent sulfur allergies.

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

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