Comparison of the ocular beta-blockers

Toxicity profiles of fixed-combination eye drops for glaucoma therapy using cultivated human corneal epithelial sheets

PURPOSE

We aimed to investigate the toxicity of 6 fixed-combination drugs for glaucoma therapy using human corneal epithelial sheets (HCES).

STUDY DESIGN

Experimental.

MATERIALS AND METHODS

We used 6 kinds of commercially available fixed-combination drugs: latanoprost/carteolol (LAT/CAR), latanoprost/timolol (LAT/TIM), tafluprost/timolol (TAF/TIM), travoprost/timolol (TRA/TIM), brinzolamide/timolol (BRZ/TIM), and dorzolamide/timolol (DRZ/TIM) including different preservatives. The cell viability and barrier function of the HCES after exposure to the eye drops for 10 or 30 minutes were assessed using the WST-1 assay and transepithelial electrical resistance (TEER) measurements, respectively. The HCES were also evaluated using hematoxylin and eosin (HE) staining and transmission electron microscopy.

RESULTS

The cell viability significantly decreased in the HCES treated with LAT/TIM or DRZ/TIM after 10 and 30 minutes and in those treated with BRZ/TIM after 30 minutes. The barrier function increased significantly in the HCES treated with LAT/CAR. Histologically, the HCES were damaged after treatment with LAT/TIM, BRZ/TIM, or DRZ/TIM for 30 minutes. Transmission electron microscopy indicated narrow intercellular spaces and multiple intercellular junctions in the HCES treated with LAT/CAR, TAF/TIM, or TRA/TIM. The HCES treated with DRZ/TIM, BRZ/TIM, or LAT/TIM contained cytoplasmic vacuoles and collapsed cellular structures.

CONCLUSION

Glaucoma fixed-combination eye drops demonstrated a different toxic effect on the cell viability, barrier function, and morphologic changes of HCES.

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.

Pharmacotherapy of intraocular pressure: part I. Parasympathomimetic, sympathomimetic and sympatholytics

Elevated intraocular pressure (IOP) has been recognized as the major risk factor for the development of glaucoma and a wide range of options are now available to reduce it: medical treatment, laser, filtering, or cyclodestructive surgery (alone or in combination). All these modalities act by decreasing eye pressure and, thereby, protecting the optic nerve head from a mechanic direct and/or vascular indirect insult. Topical medical therapy represents the first-choice treatment and, in most cases, it effectively controls IOP, avoiding the occurrence of further optic nerve damage. All medications lower IOP in two main ways: decreasing the production of aqueous humour or by increasing its outflow from the eye. Consequently, antiglaucoma drugs either suppress aqueous humour formation (beta-adrenergic antagonists, carbonic anhydrase inhibitors, and alpha-2-adrenergic agonists) or raise aqueous humour outflow throughout the conventional (e.g., pilocarpine) or uveoscleral (prostaglandin FP receptor agonists, and prostamides) route. In addition, fixed and unfixed combinations of antiglaucoma compounds have also been available for patients requiring more than one type of medication. This review, which is part one of two (please see Expert Opinion on Pharmacotherapy 10 (17)) briefly considers the characteristics of sympathomimetic, sympatholytics and parasympathomimetic commonly employed in the medical treatment of glaucoma, mainly the primary open-angle form, focusing the discussion on the clinical evidence supporting the use of these three classes of compound.

3,4-Diamino-1,2,5-thiadiazole as potent and selective CXCR2 antagonists

A series of potent and selective 3,4-diamino-1,2,5-thiadiazoles were prepared and found to show excellent binding affinities towards CXCR2 receptor.

Molecular design for enhancement of ocular penetration

Over the past two decades, many oral drugs have been designed in consideration of physicochemical properties to attain optimal pharmacokinetic properties. This strategy significantly reduced attrition in drug development owing to inadequate pharmacokinetics during the last decade. On the other hand, most ophthalmic drugs are generated from reformulation of other therapeutic dosage forms. Therefore, the modification of formulations has been used mainly as the approach to improve ocular pharmacokinetics. However, to maximize ocular pharmacokinetic properties, a specific molecular design for ocular drug is preferable. Passive diffusion of drugs across the cornea membranes requires appropriate lipophilicity and aqueous solubility. Improvement of such physicochemical properties has been achieved by structure optimization or prodrug approaches. This review discusses the current knowledge about ophthalmic drugs adapted from systemic drugs and molecular design for ocular drugs. I propose the approaches for molecular design to obtain the optimal ocular penetration into anterior segment based on published studies to date.

Pharmacogenetics of ophthalmic topical beta-blockers

Glaucoma is the second leading cause of blindness worldwide. The primary glaucoma risk factor is elevated intraocular pressure. Topical beta-blockers are affordable and widely used to lower intraocular pressure. Genetic variability has been postulated to contribute to interpersonal differences in efficacy and safety of topical beta-blockers. This review summarizes clinically significant polymorphisms that have been identified in the beta-adrenergic receptors (ADRB1, ADRB2 and ADRB3). The implications of polymorphisms in CYP2D6 are also discussed. Although the candidate-gene approach has facilitated significant progress in our understanding of the genetic basis of glaucoma treatment response, most drug responses involve a large number of genes, each containing multiple polymorphisms. Genome-wide association studies may yield a more comprehensive set of polymorphisms associated with glaucoma outcomes. An understanding of the genetic mechanisms associated with variability in individual responses to topical beta-blockers may advance individualized treatment at a lower cost.

Ophthalmic drug design based on the metabolic activity of the eye: soft drugs and chemical delivery systems

Despite its apparent easy accessibility, the eye is, in fact, well protected against the absorption of foreign materials, including therapeutic agents, by the eyelids, by the tear-flow, and by the permeability barriers imposed by the cornea on one side and the blood-retinal barrier on the other. Most existing ophthalmic drugs were adapted from other therapeutic applications and were not specifically developed for the treatment of eye diseases; hence, they are not well suited to provide eye-specific effects without causing systemic side effects. A real breakthrough in the area of ophthalmic therapeutics can be achieved only by specifically designing new drugs for ophthalmic applications to incorporate the possibility of eye targeting into their chemical structure. Possibilities provided along these lines by designing chemical delivery systems (CDSs) and soft drugs within the framework of retrometabolic drug design are reviewed here. Both are general concept applicable in almost any therapeutic area. This review will concentrate on beta-adrenergic agonists and anti-inflammatory corticosteroids, where clinical results obtained with new chemical entities, such as betaxoxime, adaprolol, loteprednol etabonate, and etiprednol dicloacetate, exist to support the advantages of such metabolism-focused, ophthalmic-specific drug design approaches.

An efficient asymmetric synthesis of (S)-atenolol: using hydrolytic kinetic resolution

Enantiomerically pure (S)-atenolol was prepared by using (R,R) salen Co(III) complex for the resolution of terminal epoxide. This process was carried out at room temperature in excellent enantio selectivity. The method can be applied for large-scale preparation of (S)-atenolol without any problem.

Changing therapeutic paradigms in glaucoma management

Glaucoma is a family of diseases commonly characterised by progressive optic neuropathy with associated visual field deficits for which elevated intraocular pressure (IOP) is one of the primary risk factors. For more than a century the main goal of glaucoma management has been to eliminate the risk associated with elevated IOP. In recent years, accumulating evidence of pressure-independent causes of glaucomatous optic neuropathy has led to the recognition that lowering IOP alone may often be insufficient for the long-term preservation of visual function. An innovative therapeutic approach is now emerging to prevent progression of glaucomatous optic neuropathy and preserve vision, irrespective of disease aetiology: direct protection of the optic nerve. In addition to reducing the risk associated with elevated IOP, this neuroprotective approach will augment the overall goal of preserving the optic nerve through direct promotion of retinal ganglion cell (RGC) survival and/or prevention of RGC death. Although no currently available compounds have been clinically demonstrated to provide neuroprotective benefit in glaucoma, recent preclinical studies have shown that alpha-adrenergic agonists, such as brimonidine, provide neuroprotective benefits, as well as excellent IOP lowering efficacy. In addition, new agents with promising neuroprotective utility that are emerging from other studies are now being investigated for efficacy in glaucoma. The review discusses recently introduced compounds and new drugs in development with regard to their potential value in conventional and/or neuroprotective strategies for vision sparing in glaucoma.

Brimonidine

Brimonidine tartrate is a highly selective alpha2-adrenergic receptor agonist indicated for the chronic treatment of glaucoma and ocular hypertension. Glaucoma, a serious worldwide public health problem causing blindness in 5.2 million people, is treated by drugs that lower the intraocular pressure (IOP), a primary risk factor in glaucomatous optic neuropathy. Currently, beta-blockers are the most common therapy. In two 12-month clinical comparison trials with timolol 0.5% (n = 926), twice-daily brimonidine produced IOP lowering comparable to twice-daily timolol. In a 3-month trial with betaxolol 0.25% suspension (n = 206), twice-daily brimonidine was more effective in lowering IOP than twice-daily betaxolol. Brimonidine was well-tolerated ocularly and systemically in these trials. It caused no clinically significant mean changes in heart rate or blood pressure. Brimonidine produced no significant effect on FEV1 in clinical trials, and it is not contraindicated in patients with cardiopulmonary disease. Brimonidine 0.2% dosed twice daily has clinical utility as a first-line drug therapy. It is an effective and safe alternative to beta-blockers, particularly in patients at risk for pulmonary or cardiovascular disease. It decreases aqueous humour production and increases uveoscleral outflow, and has an additive ocular hypotensive effect used concomitantly with other agents. Brimonidine has demonstrated neuroprotective properties in laboratory animal studies. Additional studies are warranted to determine whether brimonidine has clinical benefit in protecting the optic nerve head from glaucomatous damage. Brimonidine is an important contribution to glaucoma management.

Persistency and clinical outcomes associated with latanoprost and beta-blocker monotherapy: evidence from a European retrospective cohort study

PURPOSE

To evaluate persistency (time on initial therapy) and the clinical impact of latanoprost versus beta-blocker monotherapy in treating glaucoma.

METHODS

This observational, multicenter, retrospective medical chart review study conducted in four European countries included patients with primary open-angle glaucoma or ocular hypertension who began their first glaucoma treatment with latanoprost or a beta-blocker between November 1996 and November 1998. Persistency and glaucoma-related clinical outcomes data were abstracted for the 2 years following treatment initiation.

RESULTS

In all, 260 patient charts were analyzed (94 latanoprost, 166 beta-blocker). Patients in the latanoprost group stayed on therapy twice as long as those who received a beta-blocker (p < 0.0001). After adjusting for baseline characteristics, patients receiving a beta-blocker as initial therapy were 3.8 times more likely to change therapy than those initially treated with latanoprost (p < 0.0001). Patients in the latanoprost group also experienced greater mean decreases in intraocular pressure (IOP) than those receiving a beta-blocker (7.4 mmHg versus 4.6 mmHg, respectively; p < 0.0001), and fewer had worsened optic nerve head excavation (1.7% versus 14.2%, respectively; p < 0.05) by the time of their first therapy change or last study visit, whichever came first.

CONCLUSIONS

Over a 2-year period, latanoprost was associated with significantly greater persistency and better clinical IOP outcomes compared with beta-blocker therapy.

Health economics, economic evaluation, and glaucoma

Glaucoma has not received a great deal of attention from health economists in the past, partly due to the fact that no new treatments have been introduced for some time. Economic evaluation is generally performed for new technologies, to assess their cost-effectiveness compared with current treatments, to estimate the potential changes in the use of health care resources that their introduction may produce, and to make decisions about their reimbursement status and formulary inclusion. Economic studies in glaucoma have been largely limited to studies about cost, because a useful outcome measure has been lacking. Therapy aims at reducing intraocular pressure, but the data to estimate the absolute risk of vision loss due to high pressure have been lacking. Hence, it has been impossible to assess the benefit of treatments in terms of their ability to reduce blindness. However, as new out knowledge about these issues increases and more data become available, such studies become possible. This review illustrates the issues encountered when performing economic evaluation in glaucoma and reviews the current economic literature in the field.

Medical treatment of normal tension glaucoma

Normal-tension glaucoma was previously thought to be pressure insensitive, as medical treatment hardly reduced intraocular pressure and it did not prevent visual field loss. In the last decade, however, evidence has shown that the treatment of normal-tension glaucoma by lowering intraocular pressure can slow the deterioration of visual fields, hence the glaucomatous process. It was shown that a reduction of IOP of at least 30% is needed to induce a favorable alteration in the course of normal-tension glaucoma. New agents, such as prostaglandin analogs, the alpha(2)-adrenoceptor agonist brimonidine, and carbonic anhydrase inhibitors, have become available and may be of use in the treatment of normal-tension glaucoma. Monotherapy with prostaglandin analogs may meet the target of a reduction of IOP with 30%, but combination therapy will be needed in many cases. Few studies have been performed with brimonidine, travoprost, and bimatoprost, and it is suggested that more attention should be given to studies with these agents, as about 30% of patients with open angles and glaucomatous visual field defects have normal-tension glaucoma. Although neuroprotection is the goal of the future, no hard data are available yet which demonstrate that treatment with these agents will indeed result in preservation of visual fields.

Glaucoma medical treatment--2002: does yearly cost now equal the year?

BACKGROUND

To review costs of the wide array of glaucoma medications available today as well as patient-assistance programs.

METHODS

Potential yearly costs for current frequently used single and multiple drug therapies were determined, taking into account the actual (not labeled) volume of drops in the bottled medications. Alternative modes for obtaining medications, such as compassionate-use programs, were also surveyed.

RESULTS

"Maximum" medical therapy may cost over $2000 per year. Allergan, Ciba, Merck, Pharmacia-Upjohn, and Alcon offer patient-assistance programs of variable simplicity of use.

DISCUSSION

The cost of maximum glaucoma medical therapy can assume a significant proportion of an elderly patient's yearly income.

Travoprost--a new prostaglandin analogue for the treatment of glaucoma

Travoprost, a highly selective and potent analogue of the prostaglandin PGF(2)(alpha), has recently been approved and marketed as a topical ocular hypotensive agent for the treatment of ocular hypertension and glaucoma. Following absorption into the eye, the free acid form of travoprost interacts with the endogenous FP prostanoid receptor to enhance aqueous humor outflow and lower intraocular pressure (IOP). Travoprost is distinguished from other marketed prostaglandin analogues in that it is a full agonist at the prostaglandin receptor. It is also highly selective with little or no affinity for other prostanoid or non-prostanoid receptors in the eye. Travoprost provides robust lowering of IOP with little diurnal fluctuation and results in low target pressures in a large percentage of patients. In controlled clinical trials, travoprost 0.004% o.d. used as monotherapy produced greater IOP reduction than timolol 0.5% b.i.d. and equal or greater reduction than latanoprost 0.005%o.d. Travoprost 0.004% was also shown to be an effective adjunctive agent offering an additional 5 - 7 mmHg IOP reduction in patients inadequately controlled on timolol 0.5%. Subgroup analysis of a large Phase III trial revealed travoprost 0.004% to be significantly more effective at lowering IOP in African American patients by almost 2 mmHg compared to non-African Americans. Moreover, a higher percentage of African American patients responded to travoprost 0.004% and reached lower target pressures than with either latanoprost 0.005% or timolol 0.5%. Travoprost is a very stable compound, maintaining its efficacy following exposure to extremely low and high temperatures, repeated freezing and thawing and exposure to light. Throughout all clinical trials, travoprost was found to be safe and well-tolerated with very few (< 5%) discontinuations due to adverse events. Travoprost 0.004% represents a clinically significant advance for the treatment of glaucoma and ocular hypertension, offering superior IOP reduction and diurnal control, especially among African American patients, in a safe, well-tolerated, stable formulation.

Influence of socioeconomic status on drug selection for the elderly in Canada

OBJECTIVE

To examine the association between socioeconomic status, as indicated by neighborhood median income levels, and physician drug selection between older, less expensive generic drugs and newer, more expensive brand-name drugs for elderly patients initiating drug therapy in a universal healthcare system.

METHODS

We conducted a population-based, retrospective, cross-sectional study. Using healthcare administrative databases, we assessed the medication profiles of 128 314 patients from more than 1.4 million residents of Ontario > or =65 years old initiating antipsychotic, hydroxymethylglutaryl-coenzyme A reductase inhibitor (statin), or ocular beta-blocker drug therapy from January 1, 1998, through December 31, 1999. We examined the selection of older generic drugs relative to newer brand-name agents for patients in each of 5 income quintiles.

RESULTS

Overall, brand-name drug prescribing modestly increased with increasing income quintile after adjusting for patient age and gender (61.2% in the lowest income quintile vs. 64.1% in the highest income quintile; p value for trend < 0.001). Significant risk ratios comparing the highest with the lowest income-quintile patients were observed for selection of newer, brand-name antipsychotics (RR 1.14; 95% CI 1.06 to 1.23), older generic statins (RR 0.86; 95% CI 0.77 to 0.95), and newer, brand-name ocular beta-blockers (RR 1.13; 95% CI 1.02 to 1.25).

CONCLUSIONS

This study suggests that income-related differences in treatment selection by physicians may exist. The reasons for these differences and subsequent impact on health outcomes warrant further investigation.

A 7 year prospective comparative study of three topical beta blockers in the management of primary open angle glaucoma

AIM

To determine the long term efficacy of monotherapy with topically applied beta blocking agents and to determine whether selective beta blockers were able to preserve the visual field more effectively than non-selective agents.

METHOD

A prospective randomised, open, comparative study of three topically applied beta blockers-timolol, betaxolol, and carteolol-was carried out on 153 patients (280 eyes) with newly diagnosed open angle glaucoma. Those patients who were not withdrawn were followed by the same observers for a minimum of 2 years and a maximum of 7 years, with clinical observations, Goldmann tonometry and 24.2 Humphrey visual field analysis.

RESULTS

All three drugs lowered the IOP significantly from untreated levels but betaxolol took up to 12 months in some instances to reach the maximum pressure reduction. After 7 years only 43% of the eyes begun on timolol, 34% of those started on carteolol, and 29% of those on betaxolol were still being treated with these medications alone. Visual fields were analysed throughout the trial by CPSD and MD and at the end by linear regression analysis (PROGRESSOR). The visual fields remained the same without apparent improvement or deterioration throughout the period of follow up. Eight patients (11 eyes) were withdrawn because of continuing field loss in spite of reduction in IOP (six using carteolol and five using betaxolol).

CONCLUSIONS

Analysis shows that less than half the eyes initially treated with topical beta blockers might be expected to still be being treated with their original medication after 5 years. The rest required either additional medication or trabeculectomy. There was no statistically significant improvement or deterioration in the visual fields over a 7 year period. On the evidence of this trial there are no particular advantages in using selective beta blockers.

Meta-analysis of the effect of latanoprost and brimonidine on intraocular pressure in the treatment of glaucoma

OBJECTIVE

The purpose of this study was to indirectly quantify and compare the intraocular pressure (IOP)-lowering effects of latanoprost and brimonidine eye drops at baseline and after 3 and 6 months in the treatment of primary open-angle glaucoma.

METHODS

This meta-analysis combined data from all randomized controlled trials comparing the effects on IOP of latanoprost and brimonidine treatment in adults with a baseline IOP > or =20 mm Hg. MEDLINE and EMBASE were searched for reports of the ophthalmic administration of either drug versus the other, placebo, or active therapy. Included studies reported IOP as either means or differences (with SD or SE) and sample sizes. A random-effects model was used to pool data within each drug group. As a proxy for success rates, area under the curve (AUC) was calculated for the proportion of patients having an IOP <20 mm Hg.

RESULTS

One hundred fifty-five articles reporting on 158 trials were identified; 147 papers were rejected (141 were not randomized controlled trials, 5 were duplicates, and 1 had nonextractable data), leaving 9 trials from 8 articles. A total of 2152 patients were included in the meta-analysis: 597 received latanoprost, 571 received brimonidine, and the remainder received timolol or betaxolol. Baseline IOPs were similar in patients randomized to latanoprost or brimonidine (25.3 and 24.6 mm Hg, respectively). At 3 months, latanoprost and brimonidine reduced IOP by 8.4 and 6.5 mm Hg, respectively (P = 0.004 latanoprost vs brimonidine), and at 6 months by 8.0 and 6.2 mm Hg, respectively (P = 0.045). AUC was 0.834 and 0.675 at 3 months for latanoprost and brimonidine, respectively, and 0.817 and 0.715 at 6 months, respectively (both, P < 0.001).

CONCLUSIONS

This indirect comparison of data from the available randomized clinical trials showed latanoprost to be statistically superior to brimonidine in reducing IOP in adults with primary open-angle glaucoma. Additional long-term, head-to-head comparisons of the efficacy, safety, and cost of latanoprost and brimonidine are needed to support and supplement these findings.

Topical ophthalmic beta blockers may cause release of histamine through cytotoxic effects on inflammatory cells

AIM

To evaluate the effects of beta blockers used in ophthalmology on the release of histamine from mixed cell preparations containing human leucocytes and basophils.

METHODS

A mixed leucocyte and basophil preparation was obtained from venous blood of healthy non-atopic volunteers. Cell preparations were then incubated with betaxolol, metipranolol, timolol, or carteolol. After incubation for 1 hour the histamine content of the supernatant was analysed by automated fluorometric analysis. Cell viability was tested by measuring lactate dehydrogenase (LDH) concentrations.

RESULTS

Betaxolol and metipranolol in concentrations between 10(-2) M and 10(-3) M liberated histamine from human blood cells in a dose dependent manner. Carteolol and timolol had no effect on histamine at these concentrations. At the same concentrations LDH was also detected in the supernatants of cell suspensions incubated with metipranolol or betaxolol.

CONCLUSIONS

Betaxolol and metipranolol induce substantial histamine release from human leucocytes, probably as a result of their cytotoxic effect.

Betaxolol, a beta(1)-adrenoceptor antagonist, reduces Na(+) influx into cortical synaptosomes by direct interaction with Na(+) channels: comparison with other beta-adrenoceptor antagonists

Betaxolol, a beta(1)-adrenoceptor antagonist used for the treatment of glaucoma, is known to be neuroprotective in paradigms of ischaemia/excitotoxicity. In this study, we examined whether betaxolol and other beta-adrenoceptor antagonists interact directly with neurotoxin binding to sites 1 and 2 of the voltage-sensitive sodium channel (Na(+) channel) in rat cerebrocortical synaptosomes. Betaxolol inhibited specific [(3)H]-batrachotoxinin-A 20-alpha-benzoate ([(3)H]-BTX-B) binding to neurotoxin site 2 in a concentration-dependent manner with an IC(50) value of 9.8 microM. Comparison of all the beta-adrenoceptor antagonists tested revealed a potency order of propranolol>betaxolol approximately levobetaxolol>levobunolol approximately carteolol>/=timolol>atenolol. None of the drugs caused a significant inhibition of [(3)H]-saxitoxin binding to neurotoxin receptor site 1, even at concentrations as high as 250 microM. Saturation experiments showed that betaxolol increased the K(D) of [(3)H]-BTX-B binding but had no effect on the B(max). The association kinetics of [(3)H]-BTX-B were unaffected by betaxolol, but the drug significantly accelerated the dissociation rate of the radioligand. These findings argue for a competitive, indirect, allosteric mode of inhibition of [(3)H]-BTX-B binding by betaxolol. Betaxolol inhibited veratridine-stimulated Na(+) influx in rat cortical synaptosomes with an IC(50) value of 28. 3 microM. Carteolol, levobunolol, timolol and atenolol were significantly less effective than betaxolol at reducing veratridine-evoked Na(+) influx. The ability of betaxolol to interact with neurotoxin site 2 of the Na(+) channel and inhibit Na(+) influx may have a role in its neuroprotective action in paradigms of excitotoxicity/ischaemia and in its therapeutic effect in glaucoma.

The effectiveness and safety of brimonidine as mono-, combination, or replacement therapy for patients with primary open-angle glaucoma or ocular hypertension: a post hoc analysis of an open-label community trial. Glaucoma Trial Study Group

The purpose of this study was to determine the effectiveness and safety of brimonidine 0.2% (Alphagan, Allergan Inc., Irvine, CA) as mono-, combination, or replacement therapy for reducing intraocular pressure (IOP) in patients with primary open-angle glaucoma or ocular hypertension. The study method was an open-label, comparative clinical evaluation involving 2335 patients. During the 2-month trial, data were collected at baseline (visit 1), month 1 (visit 2), and month 2 (visit 3). Various parameters were evaluated, including glaucoma medications (visit 1), IOP (visit 1-visit 3), and adverse events. A subset cohort of 1254 patients was selected that met specific study criteria. Data from these 1254 patients were used to evaluate adverse events and the change in IOP from visit 1 to visit 3. Patient data were grouped according to specific drug regimen, and drug regimens were categorized into supergroups of mono-, combination, and replacement therapy. The results of the study revealed that the overall mean change in IOP for 1) monotherapy (n = 240) was -5.07 mm Hg (-20.2%), 2) combination therapy (n = 554) was -4.01 mm Hg (-16.9%), 3) replacement therapy (n = 460) was -2.33 mm Hg (-9.8%), and 4) overall (n = 1254) was -3.59 mm Hg (-14.9%) (p < 0.001 for all changes). Overall, 6.0% of the subjects reported adverse events, with no hypersensitivity or unexpected systemic or ocular adverse events. Eighty-five percent (85%) of clinicians rated brimonidine as "good" to "excellent". In conclusion, brimonidine is safe and effectively lowers IOP when used as mono-, combination, or replacement therapy as observed in a large community population.

The role of brimonidine in the treatment of open-angle glaucoma

At present, medical therapy is the first line of attack against primary open-angle glaucoma. beta-blockers, miotics, sympathomimetics, carbonic anhydrase inhibitors, and prostaglandins have been used with varying degrees of success. The alpha 2-agonists, clonidine, apraclonidine, and now brimonidine are powerful inhibitors of aqueous humor production, thereby lowering intraocular pressure (IOP) in these patients. Brimonidine is emerging as a potential first-line therapy for primary open-angle glaucoma, with a peak IOP-lowering efficacy comparable to that of timolol, but without timolol's adverse cardiopulmonary side effects. Brimonidine promises to be an important new drug to help meet the therapeutic challenges faced by ophthalmologists in treating glaucoma.