Comparison of a non-preserved 0.1% T-Gel eye gel (single dose unit) with a preserved 0.1% T-Gel eye gel (multidose) in ocular hypertension and glaucomatous patients

Comparative efficacy and safety of preserved versus preservative-free beta-blockers in patients with glaucoma or ocular hypertension: a systematic review

Preservative-free topical medications have been introduced for glaucoma care to reduce ocular adverse events associated with preservatives. This is a systematic review and meta-analysis of randomized clinical trials (RCTs) comparing the efficacy and safety of beta-blockers, or combination using beta-blockers, with and without preservatives. PubMed, EMBASE and Web of Science were examined. Risk of bias was assessed using the Cochrane Handbook for Systematic Reviews. The primary outcome was change in intraocular pressure (IOP) from baseline to final follow-up. Secondary outcomes included ocular and systemic side effects, and other clinical and quality of life outcomes. Of 242 records identified, seven RCTs (1125 patients) were included. The follow-up period ranged from one to 12 months. Timolol was used in five studies, and two studies used a combination (timolol with bimatoprost or dorzolamide). The difference in mean change (MD) in IOP between the preservative-free and the preserved drugs was statistically significant but not clinically relevant: (MD 0.29 mmHg, 95% confidence interval 0.07-0.51 mmHg, p = 0.010; moderate-certainty evidence). Regarding adverse events: Level of evidence for all ocular surface outcome was low or very low and reported in few studies. No significant difference was observed on ocular surface symptoms. Tear break-up time (TBUT) was better with preservative-free drops (p < 0.001). Schirmer's test was better in the preservative-free group (p < 0.001). Level of evidence for all ocular surface outcomes was low or very low. There was no difference in other secondary outcomes. We found no clinically relevant difference in mean change in IOP between the preserved and the preservative-free treatments. Data on adverse events used different methods and were incompletely reported. Although some measures of ocular surface health favoured preservative-free medications, more evidence is needed. The increasing use of preservative-free drops may be associated with better ocular surface and tolerability, but strong evidence from RCTs would be welcome.

Noninferiority of Preservative-free Versus BAK-preserved Latanoprost-timolol Fixed Combination Eye Drops in Patients With Open-angle Glaucoma or Ocular Hypertension

PRéCIS:: Noninferiority of efficacy was demonstrated for a preservative-free latanoprost-timolol fixed combination compared with a BAK-containing formulation at 84 days after treatment in patients with open-angle glaucoma or ocular hypertension.

PURPOSE

The purpose of this study was to compare the effect on intraocular pressure and safety of preservative-free latanoprost-timolol fixed combination (T2347) to benzalkonium chloride-preserved latanoprost-timolol fixed combination in patients with open-angle glaucoma or ocular hypertension.

METHODS

Phase III, randomized, parallel-group, investigator-masked study in 10 countries. A total of 242 patients aged 18 years or older with open-angle glaucoma or ocular hypertension in both eyes controlled with a preserved latanoprost-timolol fixed combination (15.7±2.4 mm Hg overall before inclusion) were randomized at day 0 with no washout period to receive the preservative-free alternative T2347 (N=127) or remain on the preserved comparator (N=115) for 84 days. Intraocular pressure changes from day 0 were measured at 9:00 am (±1 hour) on day 42 and day 84, and noninferiority of T2347 to the preserved comparator was analyzed statistically at day 84. Safety parameters were also reported.

RESULTS

The mean change in intraocular pressure from baseline to day 84 was -0.49±1.80 mm Hg for preservative-free T2347 and -0.49±2.25 mm Hg for the preserved comparator. These results met the noninferiority limits. Similar results were observed at day 42. There was no difference between groups in the incidence of adverse events or ocular signs. The total ocular symptoms score was better for T2347 than BPLT upon instillation at day 84 (45.9%/44.3%/9.8% of patients with improvement/no change/worsening vs. 33.6%/47.3%/19.1%; P=0.021), reflecting improvements in individual symptoms such as irritation/burning/stinging (P<0.001), and itching (P<0.01) on day 84.

CONCLUSIONS

Preservative-free latanoprost-timolol fixed combination T2347 showed noninferior efficacy compared with the preserved comparator and was well tolerated.

Timolol 0.1% in Glaucomatous Patients: Efficacy, Tolerance, and Quality of Life

Glaucoma is a progressive, chronic optic neuropathy characterized by a typical visual field defects. Four main classes of topical medication are actually available on the market: beta-blockers, prostaglandins, alpha2-agonists, and topical carbonic anhydrase inhibitor to treat intraocular pressure (IOP). The aim of this review is to outline the efficacy of timolol and to evaluate the impact of this treatment on patients' quality of life. Among beta-blockers, timolol is most used at three different concentrations: 0.1%, 0.25%, and 0.5%. While the first one is a gel, the other two products are solution. Timolol has few topical side effects, while it has some important systemic side effects on the cardiac and respiratory systems. The balance between efficacy and safety is always the main aspect to care patients. Because of the less efficacy of timolol 0.1% solution, the possibility to use carbomers as vehicle in the gel drops helped timolol 0.1 to be used in clinics, extending the time contact between the active ingredient and the surface of the cornea. Using preservative-free timolol 0.1 for treatment, IOP was at the same level of the other beta-blockers at higher concentration, but it was better tolerated. Preservative-free treatment improved the quality of life reducing dry-eye like symptoms; furthermore, the presence of an artificial tear in the medication bottle could help adherence. The once daily dosing improves compliance.

Ocular Surface Disease and Glaucoma Medications: A Clinical Approach

OBJECTIVES

Ocular surface disease frequently coexists with glaucoma and may be initiated or exacerbated by topical glaucoma medications. We performed a review of current literature to assess the prevalence, causes, and treatment of ocular surface disease in glaucoma patients, specifically those on topical therapy.

METHODS

A Pubmed database search was conducted. A total of 720 articles published from 1972 to 2018 were found in relation with ocular surface disease, glaucoma, and glaucoma medications. Of these, 102 articles were included in this analysis. We included primary and empirical studies for patients on topical glaucoma medications. Exclusion criteria included case reports, non-English studies, and articles unrelated to the primary subject of this review.

RESULTS

Ocular surface disease among normal and glaucomatous eyes was evaluated based on diagnostic testing including clinical examination and questionnaires to determine visual function and quality of life. Glaucoma medications can be associated with toxicities to the ocular surface, most often due to the nature of the preservative included in the medication; however, the incidence of toxicity can be mitigated by the use of preservative free medications, decreased preservative medications, or treatment of dry eye disease. Treatment of glaucoma with laser trabeculoplasty or minimally invasive glaucoma surgeries that spare the conjunctiva and the cornea may avoid or decrease reliance on topical glaucoma medications, potentially avoiding the initiation or progression of ocular surface disease.

CONCLUSIONS

Recognition and treatment of ocular surface disease in glaucoma patients may improve patient quality of life and medication adherence. This may ultimately improve glaucoma treatment outcomes.

Preservative-Free Prostaglandin Analogs and Prostaglandin/Timolol Fixed Combinations in the Treatment of Glaucoma: Efficacy, Safety and Potential Advantages

Glaucoma therapy-related ocular surface disease (OSD) is a serious pathology with a broad spectrum of insidious clinical presentations and complex pathogenesis that undermines long-term glaucoma care. Preservatives, especially benzalkonium chloride (BAK), contained in topical intraocular pressure-lowering medications frequently cause or aggravate OSD in glaucoma. Management of these patients is challenging, and to date often empirical due to the scarcity of controlled long-term clinical trials. Most of the available data are extracted from case series and retrospective analysis. Preservative-free prostaglandins and prostaglandin/timolol fixed combinations are novel options developed to remove the harmful impact of preservatives, especially BAK, upon ocular tissues. Based on what is currently known on the value of preservative-free antiglaucoma therapies it is tempting to speculate how these new therapies may affect the future medical management of all glaucoma patients. This article provides a comprehensive and critical review of the current literature on preservative-free prostaglandins and preservative-free prostaglandin/timolol fixed combinations.

Efficacy of Timolol 0.1% Gel and a Prostaglandin Analog in an Unfixed Combination Compared to the Corresponding Fixed Combinations

PURPOSE

To investigate the intraocular pressure (IOP) reduction with prostaglandin analogs (PGAs)-timolol fixed combinations versus the unfixed combination of the same PGAs and timolol 0.1% in gel-forming carbomer.

METHODS

Patients with primary open-angle glaucoma (POAG) receiving for at least 4 weeks the fixed combinations of PGA-timolol, administered once a day in the evening (0.005% latanoprost with 0.5% timolol, 0.004% travoprost with 0.5% timolol, 0.03% bimatoprost with 0.5% timolol) were switched to an unfixed combination of the same PGA (once a day in the evening) with timolol 0.1% in gel-forming carbomer (once a day in the morning) for at least 4 weeks. The primary endpoint was to compare efficacy of fixed vs unfixed combinations in lowering IOP. The effects of both regimens on short-term IOP fluctuations were also assessed.

RESULTS

A total of 32 patients (64 eyes) fulfilled inclusion criteria: 17 patients received latanoprost-timolol fixed combination, 9 travoprost-timolol fixed combination, 6 bimatoprost-timolol fixed combination. For all considered time periods each unfixed combination induced an IOP reduction significantly higher than the corresponding fixed combination (paired t test: p<0.05 in all measurements). The diurnal IOP reduction was significantly higher during the unfixed combinations (p<0.001). Unfixed combinations significantly decreased IOP diurnal fluctuations and increased the percentage of patients with daily IOP fluctuation ≤2 mm Hg.

CONCLUSIONS

In this pilot study, PGA and timolol seems to be more effective in POAG treatment when administered as unfixed combinations, reducing both IOP and daily fluctuations. The once a day timolol 0.1% gel-forming carbomer may be a valuable option in PGA-timolol unfixed combination regimen.

The 24-hour intraocular pressure control by tafluprost/timolol fixed combination after switching from the concomitant use of tafluprost and timolol gel-forming solution, in patients with primary open-angle glaucoma

Objective

The aim of this study was to evaluate the 24-hour intraocular pressure (IOP)-control effect of the tafluprost/timolol fixed combination (TAF/TIM-FC) in patients with primary open-angle glaucoma after they switched from the concomitant use of tafluprost and timolol gel-forming solution.

Patients and methods

Twenty patients with primary open-angle glaucoma (12 male and 8 female; mean ± SD age, 57.0±7.1 years) were included in this study. The patients were treated for 8 weeks with the concomitant administration of tafluprost and timolol gel-forming solution (evening dosing). At the end of this period, the patients underwent 24-hour IOP monitoring (measured at 21:00, 01:00, 05:00, 09:00, 13:00 and 17:00). IOP was measured with Goldmann applanation tonometer (GAT) and Icare PRO at sitting position at all timepoints and additionally, at supine position with Icare PRO tonometer at 01:00 and 05:00. The patients were then all switched to TAF/TIM-FC treatment (evening dosing). After 8 weeks, the 24-hour IOP monitoring was repeated.

Results

Nineteen patients completed the study. The mean 24-hour IOPs in the concomitant and TAF/TIM-FC phases were 13.8±2.7 vs 13.3±2.8 mmHg (P=0.0033) with the GAT in the sitting position and 13.96±2.56 vs 13.48±2.56 mmHg (P=0.0120) with the Icare PRO in habitual positions. In comparison with the concomitant phase, significantly lower IOP was observed for the TAF/TIM-FC phase at 21:00 and 01:00 with the GAT and at 01:00 with the Icare PRO. In addition, the maximum IOP and fluctuations in IOP in habitual positions were lower for the TAF/TIM-FC phase than for the concomitant phase.

Conclusion

TAF/TIM-FC showed a stable 24-hour IOP-lowering effect and was equally or more effective than the concomitant use of tafluprost and timolol gel, both when sitting and when in habitual positions.

Long term safety and tolerability of Tafluprost 0.0015% vs Timolol 0.1% preservative-free in ocular hypertensive and in primary open-angle glaucoma patients: a cross sectional study

BACKGROUND

The effects of preservatives of antiglaucoma medications on corneal surface and tear function have been widely shown in literature; it's not the same as regards the active compounds themselves. The purpose of our study was to compare Ocular Surface Disease (OSD) signs and symptoms of Tafluprost 0.0015% versus preservative free (PF) Timolol 0.1% eyedrops in ocular hypertensive (OH) and in primary open-angle glaucoma (POAG) patients.

METHODS

A cross-sectional study included patients in monotherapy for at least 36 months with Tafluprost 0.0015% (27) or PF Timolol 0.1% (24) and 20 healthy age and sex-matched volunteers. All subjects underwent clinical tests (Schirmer I and break-up time), in vivo confocal microscopy (IVCM) and were surveyed using Ocular Surface Disease Index (OSDI) and Glaucoma Symptoms Scale (GSS) questionnaires. The groups were compared with ANOVA, Kruskal-Wallis test, t-test, Mann-Whitney test and Bonferroni's adjustment of p-values.

RESULTS

No significant differences were found in questionnaires scores, clinical tests, IVCM variables between therapy groups. Tafluprost 0.0015% group showed significantly higher OSDI score, basal epithelial cells density, stromal reflectivity, sub-basal nerves tortuosity (p = 0.0000, 0.037, 0.006, 0.0000) and less GSS score, number of sub-basal nerves (p = 0.0000, 0.037) than controls but similar clinical tests results (p > 0.05). PF Timolol group had significantly higher OSDI score, basal epithelial cells density, stromal reflectivity and sub-basal nerve tortuosity (p = 0.000, 0.014, 0.008, 0.002), less GSS score, BUT and number of sub-basal nerves (p = 0.0000, 0.026, 0.003) than controls.

CONCLUSIONS

Compared to PF Timolol 0.1%, Tafluprost 0.0015% showed similar safety with regards to tear function and corneal status and a similar tolerability profile. Both therapy groups show some alterations in corneal microstructure but no side effects on tear function except for an increased tear instability in PF Timolol 0.1% group. Ophtalmologists should be aware that even PF formulations may lead to a mild ocular surface impairment.

Controversy: Is Benzalkonium Chloride Necessary in Antiglaucoma Drops?

Medical therapy is the first-line option in glaucoma management, with benzalkonium chloride (BAC) being the most frequently used preservative in antiglaucoma medications. Its use is however, known to be associated with deleterious effects on the ocular surface. This review is an attempt to critically evaluate whether BAC really is indispensable for better bioavailability of antiglaucoma drugs and consequently, better IOP control.

How to cite this article: Louati Y, Shaarawy T. Controversy: Is Benzalkonium Chloride Necessary in Antiglaucoma Drops? J Current Glau Prac 2012;6(3):104-107.

Differential pharmacology and clinical utility of preservative-free tafluprost in the treatment of ocular hypertension and glaucoma

Glaucoma is a chronic disease requiring lifelong treatment. Discomfort due to medications may affect patients’ quality of life and may cause poor compliance, which leads to poor intraocular pressure control. To minimize the side effects of long-term treatment, preparations with lower benzalkonium chloride concentrations, preservative-free preparations and alternative preservatives have been developed and reported to have a lower rate of side effects. Tafluprost, launched on the ophthalmic market in 2008, is a new 16-phenoxy analogue of prostaglandin F_2α, clinically used as an ocular hypotensive agent for the treatment of glaucoma and ocular hypertension. The safety and intraocular pressure-lowering efficacy of tafluprost has been demonstrated in various preclinical and clinical studies.

Benzalkonium chloride induces anterior chamber inflammation in previously untreated patients with ocular hypertension as measured by flare meter: a randomized clinical trial

PURPOSE

The deleterious effects of benzalkonium chloride (BAK) on the ocular surface are well known. However, few clinical data are available to prove a toxic effect at the level of the anterior chamber. The laser flare meter is a reliable tool to detect low levels of inflammation in the anterior chamber. We wanted to know whether instillation of BAK-preserved timolol in one eye would result in higher laser flare values than the instillation of preservative-free timolol in the fellow eye.

METHODS

Randomized prospective, single-masked clinical trial. Twenty-eight untreated patients with ocular hypertension were recruited. After obtaining baseline flare values, we randomly assigned one eye to BAK-preserved timolol and the fellow eye to preservative-free timolol. After 1 month, flare measurements were repeated.

RESULTS

There was a significant increase in the flare values in the two treatment regimens, but the increase in the BAK-treated eyes was higher than in the preservative-free treated eyes, and this difference in increase was statistically significant.

CONCLUSION

This is the first study to show that short-term BAK administration produces inflammation in the anterior segment of previously untreated patients whose blood-aqueous barrier was not affected by recent intraocular surgery.

Ophthalmic preservatives: focus on polyquaternium-1

INTRODUCTION

Ophthalmic preservatives, such as polyquaternium-1 (PQ-1), are critical for the inhibition of growth of microbial contaminants in multi-dose bottles of topical medications. These antimicrobial agents must have a high efficacy against pathogenic organisms, while maintaining a favorable tolerability and safety profile.

AREAS COVERED

This review focuses on the ophthalmic preservative PQ-1. For comparison purposes, the most commonly used preservative, benzalkonium chloride (BAK), is also discussed. This survey focuses primarily on data collected during the past 10 years.

EXPERT OPINION

Effective drug delivery requires more than just an active ingredient that achieves its desired biological effect on end-target tissues. In addition, drugs must be stable in the containers that they are stored in, and must possess minimal undesired local and systemic side effects that can cause patients to decrease their adherence. In addressing these concerns, specifically in topical ophthalmic drops, one must take into account the active ingredients, vehicle components and preservatives. Medications with fewer adverse effects may lead to enhanced adherence to therapy; therefore, the induction of such adverse outcomes must be considered by physicians when treating patients with chronic ocular disease. Although BAK will continue to be used in ophthalmic medications, due to its familiarity and compatibility with a broad range of topical ocular formulations, PQ-1 is certainly a viable alternative in the preservative formulary armamentarium.

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.

Incidence of new coding for dry eye and ocular infection in open-angle glaucoma and ocular hypertension patients treated with prostaglandin analogs: retrospective analysis of three medical/pharmacy claims databases

Background

To investigate the clinical relevance of two different preservative formulations, we compared 1-year incidence rates of additional coding of dry eye, ocular infection, or ocular surface disease (either dry eye or ocular infection) in open-angle glaucoma and ocular hypertension patients newly treated with latanoprost with benzalkonium chloride (BAK) or with travoprost-Z with SofZia^®.

Methods

This was a retrospective study of three U.S.-based patient-centric medical/pharmacy claims databases (MedStat, PharMetrics, i3-Ingenix). Patients were eligible if they filled a prescription for latanoprost or travoprost-Z between October 2006 and Q2 2008 (prescription date = index date) AND were continuously enrolled 6 months prior through 12 months after the index date AND had any open-angle glaucoma or ocular hypertension diagnosis within 90 days prior to the index date AND did not have an ocular surface disease diagnosis during the 180 days prior to the index date AND if they had not had a prescription for the index agent in the 180 days prior to the index date. Time to incidence of new coding for ocular surface disease in the first year post-index was estimated with a composite endpoint: diagnosis of dry eye or ocular infection by ICD-9-CM or Current Procedural Terminology code OR by prescription for cyclosporine ophthalmic emulsion or ocular antibiotics.

Results

In all, 15,933 patients were treated with latanoprost and 7670 with travoprost-Z. Over 1 year, 4.3% of latanoprost and 4.5% of travoprost-Z patients were identified with dry eye (p = 0.28), and 10.9% and 11.1%, respectively, were identified with an ocular infection (p = 0.79). The 1-year incidence of new coding for ocular surface disease also was similar across treatments (13.9% vs 14.3%, respectively; p = 0.48).

Conclusions

The retrospective analysis of three large prescription databases revealed that open-angle glaucoma and ocular hypertension patients newly treated with latanoprost preserved with BAK or travoprost-Z preserved with SofZia did not differ statistically in rates of dry eye, ocular infection, or ocular surface disease (either dry eye or ocular infection) during the first year post-index. Claims-based analyses are limited by nonrandomization and the inability to account for over-the-counter use or samples.

Timogel® vs Timolol 0.5% Ophthalmic Solution: Efficacy, Safety, and Acceptance

Purpose

To evaluate the efficacy, safety, and tolerability of Timogel® preservative-free once daily compared to timolol 0.5% ophthalmic solution bid in patients with ocular hypertension (OHT) and patients with primary open-angle glaucoma (POAG).

Methods

A total of 75 patients with OHT and patients with POAG treated with timolol 0.5% bid with intraocular pressure (IOP) ≤21 mmHg were enrolled. They underwent complete ophthalmologic examination, IOP measurements (at trough and daytime curve), evaluation of side effects, Schirmer test, break-up time [BUT], blood pressure, heart rate, ocular diastolic perfusion pressure measurements, and acceptance (Comparison of Ophthalmic Medications for Tolerability). Patients switched to Timogel® and were re-evaluated 3 months later. The analysis of variance and the Pearson χ2 tests were used to test differences between the treatments.

Results

Intraocular pressure reduction at trough was 23.6% with timolol 0.5% and 22.3% with Timogel®. No statistical differences were observed in IOP values at trough and in the daytime curve between the 2 treatments. Local and systemic side effects were less frequent with Timogel® (hazard ratio: p<0.05). Patients demonstrated a significant improvement of Schirmer test and BUT (p<0.05) and a reduction of dryness and foreign body sensation (42.6% vs 15.4%; p<0.01) after switching to Timogel®. Mild and short-lasting blurred vision after Timogel® instillation occurred in about 18.5% of patients. A total of 82% of patients were satisfied or very satisfied with Timogel® vs 61% with previous treatment (p<0.01).

Conclusions

Timogel® preservative-free dosed once every morning has a 24-hour hypotensive effect with a better safety profile than timolol 0.5% bid and it is well-accepted by patients. The once-daily dosing improved acceptance and compliance.

Medical treatment of glaucoma: present and future

INTRODUCTION

In the last decades, the therapy of glaucoma has largely shifted from surgery to medical treatment thanks to the introduction of strongly effective formulations, that is, prostaglandin analogs and fixed combinations. This clinical scenario may dramatically change in the future thanks to the progresses in biochemistry, genetics and drug delivery technology.

AREAS COVERED

This review covers the strategies currently used to achieve effective medical reduction of intraocular pressure in clinical practice; treatments that are currently been experimented in humans and that may be clinically available in the next few years; treatments at preclinical stages; and future goals of glaucoma treatment (gene therapy, ocular implants and neuroprotection).

EXPERT OPINION

Apart from an adequate reduction of intraocular pressure, effective glaucoma treatments should guarantee other characteristics: good tolerability, low problems of adherence and, possibly, multiple ways of action. From this viewpoint, a crucial clinical role may be played by drugs remodeling the trabecular meshwork (i.e., ROCK inhibitors, metalloproteinases). Other strategies such as the use of ocular implants for drug delivery, neuroprotection or gene therapy could renew glaucoma management in the future, but need long-term rigorous verification of safety and efficacy.

Current and emerging medical therapies in the treatment of glaucoma

INTRODUCTION

Glaucoma is a disease of the eye in which the optic nerve and retinal ganglion cells (RGCs) are injured, leading to the loss of the peripheral visual field and eventually to profound vision loss and blindness. Glaucoma is usually characterized by an increase in intraocular pressure (IOP), which is treated with ocular hypotensive drugs. However, both RGC apoptosis and optic nerve atrophy, due to glaucoma, can occur independently of IOP.

AREAS COVERED

This review discusses several current and emerging treatments for glaucoma. Current research is updating the known properties of a number of drugs now used to treat glaucoma. Some drugs may offer neuroprotection, not only reducing vision loss, but restoring injured or compromised RGCs and optic nerve cells. Several molecules now under development aim to lower IOP primarily by enhancing aqueous drainage through conventional pathways of the trabecular meshwork and Schlemm's canal. Gene transfer models are being investigated, and a murine-derived neurotrophic growth factor (NGF) seems to offer the promise of actually restoring visual function in some patients. Drugs that are already widely used are being re-branded in preservative-free formulations.

EXPERT OPINION

The ultimate goal in glaucoma research is to find new compounds that will not only normalize IOP, but also arrest or even reverse apoptotic damage to the optic nerve and RGCs to slow the rate of progression of the disease so that it will not interfere with the patient's ability to see and his/her quality of life. This should be obtained with affordable costs, minimal side effects and a reasonable schedule.

Preservatives in eyedrops: the good, the bad and the ugly

There is a large body of evidence from experimental and clinical studies showing that the long-term use of topical drugs may induce ocular surface changes, causing ocular discomfort, tear film instability, conjunctival inflammation, subconjunctival fibrosis, epithelial apoptosis, corneal surface impairment, and the potential risk of failure for further glaucoma surgery. Subclinical inflammation has also been described in patients receiving antiglaucoma treatments for long periods of time. However, the mechanisms involved, i.e., allergic, toxic, or inflammatory, as well as the respective roles of the active compound and the preservative in inducing the toxic and/or proinflammatory effects of ophthalmic solutions, is still being debated. The most frequently used preservative, benzalkonium chloride (BAK), has consistently demonstrated its toxic effects in laboratory, experimental, and clinical studies. As a quaternary ammonium, this compound has been shown to cause tear film instability, loss of goblet cells, conjunctival squamous metaplasia and apoptosis, disruption of the corneal epithelium barrier, and damage to deeper ocular tissues. The mechanisms causing these effects have not been fully elucidated, although the involvement of immunoinflammatory reactions with the release of proinflammatory cytokines, apoptosis, oxidative stress, as well as direct interactions with the lipid components of the tear film and cell membranes have been well established. Preservative-induced adverse effects are therefore far from being restricted to only allergic reactions, and side effects are often very difficult to identify because they mostly occur in a delayed or poorly specific manner. Care should therefore be taken to avoid the long-term use of preservatives, otherwise a less toxic alternative to BAK should be developed, as this weakly allergenic but highly toxic compound exerts dose- and time-dependent effects. On the basis of all these experimental and clinical reports, it would be advisable to use benzalkonium-free solutions whenever possible, especially in patients with the greatest exposure to high doses or prolonged treatments, in those suffering from preexisting or concomitant ocular surface diseases, and those experiencing side effects related to the ocular surface. Indeed, mild symptoms should not be underestimated, neglected, or denied, because they may very well be the apparent manifestations of more severe, potentially threatening subclinical reactions that may later cause major concerns.

Detrimental effect of preservatives in eyedrops: implications for the treatment of glaucoma

Antiglaucoma medications are often associated with ocular adverse reactions such as dry eye, and burning or stinging sensations. These undesirable effects may lead to treatment discontinuation and reduced quality of life in patients with glaucoma. Antiglaucoma medications usually contain benzalkonium chloride (BAK) as a preservative. Animal studies, in vitro studies and in vivo experiments have demonstrated various adverse effects of BAK. Clinical studies have also shown an increased incidence of adverse events with BAK and have demonstrated that the withdrawal of preservatives reduces these effects. Collectively, these data suggest that preservative-free antiglaucoma treatments have clinically relevant benefits for patients.

The effect of drop vehicle on the efficacy and side effects of topical glaucoma therapy: a review

PURPOSE OF REVIEW

Topically applied medications are frequently used in ophthalmology to treat acute and chronic conditions, and are considered to be safer than their systemically applied counterparts, due to the reduced rate of systemic side effects.

RECENT FINDINGS

Many experimental and clinical studies have reported that the long-term use of topical medications in chronic ophthalmic conditions, such as glaucoma, may adversely affect the ocular surface. Preservatives play a pivotal role in almost all multidose ophthalmic preparations, inhibiting microbial growth and preserving the active drug. Consequently, preservatives are partially responsible for ocular side effects, although the exact mechanism of these side effects is not known.

SUMMARY

The role of preservatives in the efficacy and side effects of antiglaucoma drugs is reviewed. The recent advances in preservative technologies and their role in decreasing the side effects associated with antiglaucoma drugs are also discussed.