The evolving pharmacotherapeutic profile of brimonidine, an alpha 2-adrenergic agonist, after four years of continuous use

Severe Central Nervous System and Respiratory Depression in a Neonate Following Accidental Oral Ingestion of Brimonidine Tartrate

Brimonidine is a third-generation alpha-2 adrenergic agonist and is classified as an ocular hypotensive agent. It is used for chronic glaucoma treatment by lowering intraocular pressure, crucial for preventing blindness. Brimonidine works by reducing aqueous humor production and increasing uveoscleral outflow. The improper use of brimonidine in children can result in severe adverse effects. If brimonidine eye drops are ingested orally, it can cause significant depression of the cardiorespiratory and central nervous systems. This is a case report of a 27-day-old neonate, who presented with central nervous system and respiratory depression after accidental ingestion of one drop of brimonidine tartrate ophthalmic solution. On arrival, he was having shallow breathing, a low Glasgow Coma Scale score, pinpoint pupils, and absent deep tendon reflexes. Gastric lavage was performed and supportive treatment was started. The patient showed gradual improvement and completely recovered within 48 hours.

Design, synthesis, biological evaluation, and in silico studies of quinoxaline derivatives as potent p38α MAPK inhibitors

A new series of quinoxaline derivatives possessing the hydrazone moiety were designed, synthesized, and screened for in-vitro anti-inflammatory activity by the bovine serum albumin (BSA) denaturation technique, and for antioxidant activity, by the (2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The synthesized compounds were also tested for p38α mitogen-activated protein (MAP) kinase inhibition. The in-vivo anti-inflammatory activity was assessed by the carrageenan-induced rat paw edema inhibition method. All the compounds (4a-n) exhibited moderate to high in-vitro anti-inflammatory activity. Compound 4a displayed the highest inhibitory activity in the BSA assay (83.42%) in comparison to the standard drug diclofenac sodium (82.90%), while 4d exhibited comparable activity (81.87%). The DPPH assay revealed that compounds 4a and 4d have free radical scavenging potential (74.70% and 74.34%, respectively) comparable to the standard butylated hydroxyanisole (74.09%). Furthermore, the p38α MAP kinase inhibition assay demonstrated that compound 4a is highly selective against p38α MAP kinase (IC50  = 0.042) in comparison to the standard SB203580 (IC50  = 0.044). The five most active compounds (4a-4d and 4f) with good in-vitro profiles were selected for in-vivo anti-inflammatory studies. Compounds 4a and 4d were found to display the highest activity (83.61% and 82.92% inhibition, respectively) in comparison to the standard drug diclofenac sodium (82.65% inhibition). These compounds (4a and 4d) also exhibited better ulcerogenic and lipid peroxidation profiles than diclofenac sodium. The molecular docking and molecular dynamics simulation studies were also performed and found to be in agreement with the p38α MAP kinase inhibitory activity.

Novel frontiers in neuroprotective therapies in glaucoma: Molecular and clinical aspects

In the last years, neuroprotective therapies have attracted the researcher interests as modern and challenging approach for the treatment of neurodegenerative diseases, aimed at protecting the nervous system from injuries. Glaucoma is a neurodegenerative disease characterized by progressive excavation of the optic nerve head, retinal axonal injury and corresponding vision loss that affects millions of people on a global scale. The molecular basis of the pathology is largely uncharacterized yet, and the therapeutic approaches available do not change the natural course of the disease. Therefore, in accordance with the therapeutic regimens proposed for other neurodegenerative diseases, a modern strategy to treat glaucoma includes prescription of drugs with neuroprotective activities. With respect to this, several preclinical and clinical investigations on a plethora of different drugs are currently ongoing. In this review, first, the conceptualization of the rationale for the adoption of neuroprotective strategies for retina is summarized. Second, the molecular aspects highlighting glaucoma as a neurodegenerative disease are reported. In conclusion, the molecular and pharmacological properties of most promising direct neuroprotective drugs used to delay glaucoma progression are examined, including: neurotrophic factors, NMDA receptor antagonists, the α2-adrenergic agonist, brimonidine, calcium channel blockers, antioxidant agents, nicotinamide and statins.

Brimonidine tartrate ophthalmic solution 0.025% for redness relief: an overview of safety and efficacy

INTRODUCTION

Ocular redness, or conjunctival hyperemia, is a common ophthalmic sign associated with reduced quality of life. For redness without apparent underlying pathology, topical ophthalmic decongestants have been widely used.

AREAS COVERED

Brimonidine tartrate was approved in 2017 as a topical vasoconstrictor at a 0.025% concentration for relief of ocular redness. Since then, investigators have reported on efficacy and safety findings from studies evaluating low-dose brimonidine for reducing ocular redness.

EXPERT OPINION

Brimonidine is highly selective for α₂-adrenergic receptors. Clinical trials have so far shown that the drug in low doses significantly reduces ocular redness in comparison to vehicle for up to 8 hours. Brimonidine-treated eyes did not present side effects of other vasoconstrictors, such as hypotension, cardiac arrhythmia or drowsiness. Ocular adverse events such as allergic reactions and redness rebound were also minimal. In this review, we examine in detail published literature on the mechanism of brimonidine tartrate and its efficacy and safety in relieving conjunctival hyperemia.

Recent Advances in Age-Related Macular Degeneration Therapies

Age-related macular degeneration (AMD) was described for the first time in the 1840s and is currently the leading cause of blindness for patients over 65 years in Western Countries. This disease impacts the eye’s posterior segment and damages the macula, a retina section with high levels of photoreceptor cells and responsible for the central vision. Advanced AMD stages are divided into the atrophic (dry) form and the exudative (wet) form. Atrophic AMD consists in the progressive atrophy of the retinal pigment epithelium (RPE) and the outer retinal layers, while the exudative form results in the anarchic invasion by choroidal neo-vessels of RPE and the retina. This invasion is responsible for fluid accumulation in the intra/sub-retinal spaces and for a progressive dysfunction of the photoreceptor cells. To date, the few existing anti-AMD therapies may only delay or suspend its progression, without providing cure to patients. However, in the last decade, an outstanding number of research programs targeting its different aspects have been initiated by academics and industrials. This review aims to bring together the most recent advances and insights into the mechanisms underlying AMD pathogenicity and disease evolution, and to highlight the current hypotheses towards the development of new treatments, i.e., symptomatic vs. curative. The therapeutic options and drugs proposed to tackle these mechanisms are analyzed and critically compared. A particular emphasis has been given to the therapeutic agents currently tested in clinical trials, whose results have been carefully collected and discussed whenever possible.

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.

Over-the-Counter Ocular Decongestants in the United States - Mechanisms of Action and Clinical Utility for Management of Ocular Redness

To manage ocular redness effectively, health-care practitioners require an understanding of the pathophysiology, clinical features and differential diagnosis of ocular redness, as well as comprehensive knowledge of medical therapies available and their pharmacologic properties. This review aims to provide a clinically relevant summary of the current literature on the mechanism of action, efficacy, and safety of current over-the-counter (OTC) decongestants available for reduction of ocular redness due to minor irritations. Currently marketed OTC products indicated for such use in the United States include topical solutions of tetrahydrozoline 0.05%, naphazoline 0.012% to 0.03%, and brimonidine 0.025%. All 3 agents are adrenergic receptor agonists but vary in their receptor-binding profiles: tetrahydrozoline is a selective α1 receptor agonist; naphazoline is a mixed α1/α2 receptor agonist; and brimonidine is a selective α2 receptor agonist. These OTC decongestants produce vasoconstriction of conjunctival blood vessels, which results in a rapid reduction in ocular redness. In general, ocular adverse events reported in published studies of these OTC decongestants were minimal, mild, and transient, with no significant adverse systemic effects. However, ocular decongestants with α1-adrenergic receptor agonist activity can be associated with loss of effectiveness with continued use (ie, tachyphylaxis) and rebound redness upon treatment discontinuation. In clinical trials of the selective α2-adrenergic receptor agonist brimonidine 0.025%, tachyphylaxis was not observed, and rebound redness was rarely reported.

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.

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.

Low-dose brimonidine for relief of ocular redness: integrated analysis of four clinical trials

BACKGROUND

The aim of this study was to provide an integrated analysis of safety and efficacy data for brimonidine tartrate ophthalmic solution 0.025 per cent (low-dose; Bausch & Lomb Incorporated), a topical vasoconstrictor for relief of ocular redness.

METHODS

Integrated efficacy data from two randomised, double-masked, vehicle-controlled studies in subjects with ocular redness as well as safety data from the two efficacy studies, a vehicle-controlled safety study, and a pharmacokinetic study were analysed. Efficacy outcomes analysed included investigator-assessed ocular redness (scale, 0-4) before treatment instillation and at five to 240 minutes post-instillation on Day 1, at five minutes post-instillation on Days 15 and 29, and one week after treatment discontinuation (Day 36), and redness self-assessed by subjects recorded daily in diaries. Safety assessments included adverse events, ophthalmic examinations, and rebound redness upon treatment discontinuation. Drop comfort (scale, 0-10) was a tolerability measure.

RESULTS

The efficacy population included 117 subjects (brimonidine, n = 78; vehicle, n = 39). The safety population included 635 subjects (brimonidine, n = 426; vehicle, n = 209). Investigator-assessed ocular redness was significantly lower with brimonidine versus vehicle at all post-instillation time points on Day 1 (mean change from pre-instillation of -1.4 units for brimonidine and -0.2 units for vehicle; p < 0.0001). Subject-assessed ocular redness was also significantly lower with brimonidine versus vehicle (mean treatment difference in average daily ratings of -0.9; p < 0.0001). There was no evidence of tachyphylaxis through Day 29 and rebound redness was rare. Incidence of ocular adverse events was low, the most common being reduced visual acuity (brimonidine, 4.0 per cent; vehicle, 4.3 per cent) and conjunctival hyperaemia (2.6 and 2.9 per cent, respectively). Both brimonidine and vehicle were rated as very comfortable (mean post-instillation scores, 0.4-0.5).

CONCLUSION

In this integrated analysis, low-dose brimonidine significantly reduced ocular redness with no tachyphylaxis, and minimal rebound redness, and was generally safe and well tolerated.

[The role of fixed dose combinations in the treatment of primary open-angle glaucoma]

A great number of patients with primary open-angle glaucoma require combination therapy with several hypotensive drugs of different pharmacological groups to efficiently compensate the intraocular pressure (IOP) and prevent further development of glaucoma. Although glaucoma treatment usually starts with monotherapy, several preparations administered simultaneously have stronger hypotensive effect further increased by their additive action. However, the increased frequency of instillations may lead to drug washout and decreased patient compliance. Fixed dose combinations (FDCs) are a pharmacological form of eye drops that combines two or more active drugs in a single dosage form. The frequency of FDCs administration does not exceed two per day, which is convenient for long-term application and helps improve patient compliance. FDCs tolerability tends to be higher than that of simultaneous instillations of separate monotherapy drugs, while the hypotensive in clinical trials is comparable, in some real practice trials is superior. A review of existing studies showed that FDCs are superior to monotherapy in terms of cost-effectiveness. The use of FDCs was found to be beneficial for glaucoma treatment from the viewpoints of both reaching the target IOP for preserving visual functions in glaucoma patients, and minimizing the long-term treatment costs.

Brimonidine Ophthalmic Solution 0.025% for Reduction of Ocular Redness: A Randomized Clinical Trial

SIGNIFICANCE

The α2-adrenergic receptor agonist brimonidine has been reported to induce conjunctival blanching in cataract, strabismus, laser refractive, and filtration procedures. Clinicians are often faced with red eyes with no apparent underlying pathology. Low-dose brimonidine reduced ocular redness in such subjects with efficacy maintained over 1 month and negligible rebound redness.

PURPOSE

The aim of this study was to evaluate the safety and efficacy of brimonidine tartrate ophthalmic solution 0.025% for the treatment of ocular redness.

METHODS

In this single-center, double-masked, phase 3 clinical trial, adult subjects with baseline redness of more than 1 unit in both eyes (0- to 4-unit scale) were randomized 2:1 to brimonidine 0.025% or vehicle. A single dose was administered in-office (day 1); thereafter subjects instilled treatment four times a day for 4 weeks, with clinic visits on days 15, 29, and 36 (7 days post-treatment). Efficacy end points included investigator-evaluated redness 5 to 240 minutes post-instillation on day 1 (primary); investigator-evaluated change from baseline 1, 360, and 480 minutes post-instillation on day 1, and 1 and 5 minutes post-instillation on days 15 and 29; total clearance of redness, and subject-assessed redness. Safety/tolerability measures included adverse events, rebound redness, and drop comfort.

RESULTS

Sixty subjects were randomized (n = 40 brimonidine, n = 20 vehicle). Investigator-assessed redness was lower with brimonidine versus vehicle over the 5- to 240-minute post-instillation period (mean [SE], 0.62 [0.076] vs. 1.49 [0.108]; P < .0001) and at each time point within that period (P < .0001). At 1, 360, and 480 minutes post-instillation, respectively, the mean differences (95% confidence interval) between treatments were -0.73 (-1.05 to -0.41), -0.57 (-0.84 to -0.29), and -0.39 (-0.67 to -0.10), respectively. No tachyphylaxis was evident with brimonidine on days 15 and 29, and minimal rebound redness was observed following discontinuation. Adverse events were infrequent, and brimonidine was rated as very comfortable.

CONCLUSIONS

Brimonidine 0.025% appeared safe and effective for reduction of ocular redness, with an 8-hour duration of action, no evidence of tachyphylaxis, and negligible rebound redness.

In Vitro Safety Pharmacology Profiling of Topical α-Adrenergic Agonist Treatments for Erythema of Rosacea

Background

Topical α-adrenergic agonist therapy has been developed to treat the persistent erythema of rosacea patients. Brimonidine and oxymetazoline are both topical α-adrenergic agonists.

Objectives

The objective of this in vitro safety pharmacology study was to compare the potential safety profiles of brimonidine and oxymetazoline.

Methods

Brimonidine and oxymetazoline underwent pharmacological profiling with a standard panel of 151 assays, including α-adrenergic receptors and 5-hydroxytryptamine (5-HT) receptors. A valvular interstitial cell (VIC) proliferation assay was performed with oxymetazoline hydrochloride.

Results

Brimonidine was highly selective for the α₂ adrenergic receptors, specifically α_2A, whereas oxymetazoline was found to be much less selective and was highly active against a wide range of targets. Negligible activity was observed with brimonidine at the 5-HT_2B receptor, whereas oxymetazoline had significant 5-HT_2B receptor agonist activity and caused proliferation of mitral VICs in vitro.

Conclusion

As the 5-HT_2B receptor is potentially involved in drug-induced valvulopathy, the benefit/risk ratio should be carefully considered, especially in patients with cardiovascular disease or other comorbidities.

Brimonidine's Neuroprotective Effects against Transient Ischaemia-Induced Retinal Ganglion Cell Death

Purpose

Brimonidine is a lowering pressure agent currently used in glaucoma. This chronic degenerative condition is characterised by neuronal death, and an agent which offers neuroprotection may slow down or impede the progression of neuronal cell death.

Methods

The effects of brimonidine (BMD) on the short- and long-term survival of retinal ganglion cells (RGCs) after transient retinal ischaemia are reported here using a rat model. The fluorescent tracer Fluorogold (FG) was applied to both superior colliculi to retrogradely label RGCs. A ninety-minute period of ischaemia was induced and densities of surviving RGCs were estimated over time by counting FG-labelled RGCs in 12 standard regions of each retina.

Results

Seven days after inducing transient ischaemia, there was loss of approximately half of the RGC population. Topical pre-treatment with 0.1% or 0.5% BMD prevented ischaemia-induced RGC death.

Conclusions

These results indicate that optimal neuroprotective effects against the early loss of RGCs are seen with 0.1% or 0.5% BMD. Ischaemia-induced RGC loss continued between day 7 and day 21 in the vehicle treated groups and amounted to approximately 25% of the RGC population. Topical pre-treatment with 0.1% or 0.5% BMD was also effective in reducing the slow loss of RGCs.

Effects of selective α2 -adrenergic receptor agonists on electrical field-stimulated contractions of isolated bronchi in horses

We investigated the effects of different selective α₂ -adrenergic receptor (AR) agonists (detomidine, medetomidine, xylazine, and brimonidine) on the contractions of horse-isolated bronchi induced by electrical field stimulation (EFS) and by carbachol. No effects were observed on the contraction induced by carbachol, while α₂ -AR agonists reduced EFS-evoked contractions in a concentration-related fashion. The rank order of potency (pD₂ ) was brimonidine (7.40 ± 0.20) >medetomidine (7.09 ± 0.24) >detomidine (6.13 ± 0.55) >xylazine (4.59 ± 0.16). The maximal effects (E_max ) were -56.3% ± 6.3%, -40.4% ± 6.9%, -48.6% ± 9.9%, and -72.7% ± 12.7% for brimonidine, medetomidine, detomidine, and xylazine, respectively. Adrenergic block by guanethidine enhanced the potency (8.10 ± 0.05, 7.30 ± 0.15, 6.83 ± 0.41, and 5.40 ± 0.22) and the efficacy (-95.2% ± 0.7%, -45.2% ± 11.7%, -58.5% ± 9.8%, and -97.9% ± 0.6%) of brimonidine, medetomidine, detomidine, and xylazine, respectively. Selective α₂ -AR antagonist, atipamezole, competitively antagonized the inhibition of EFS-evoked contractions induced by all agonists except xylazine. These results suggest the existence of presynaptic α₂ -ARs on cholinergic neurons, negatively regulating the release of acetylcholine in horse bronchial muscle, and that α₂ -AR agonists may be beneficial against vagally mediated bronchoconstriction.

Evaluation of Efficacy and Safety of Brimonidine Tartrate Ophthalmic Solution, 0.025% for Treatment of Ocular Redness

Purpose/Aims: This study assessed the efficacy and safety of brimonidine tartrate ophthalmic solution, 0.025% for treating ocular redness in adult subjects.

MATERIALS AND METHODS

This was a single-center, double-masked, randomized, vehicle-controlled, parallel-group study in subjects ≥40 years, with ocular redness. Subjects were randomized 2:1 to brimonidine or vehicle, instilled QID for four weeks. Subjects completed four visits, the last occurring one week after treatment discontinuation. The investigator assessed ocular redness on a scale of 0-4 pre-instillation and 5-240 minutes post-instillation on Day 0, pre-instillation and 5 minutes post-instillation on Days 14 and 28, and on Day35; subjects assessed redness in diaries throughout the 28-day treatment period and following treatment discontinuation. Safety assessments included adverse events (AEs), rebound redness on treatment discontinuation, comprehensive ophthalmic exams, and vital signs. Drop comfort was assessed upon instillation, and 30 seconds and 1 minute post-instillation at Day 0.

RESULTS

Fifty-seven subjects (brimonidine, n = 38; vehicle, n = 19) were randomized. Investigator-assessed ocular redness was significantly reduced with brimonidine across the entire post-instillation time period (overall treatment difference: -1.37; P < 0.0001) and at all individual time points (P < 0.0001). Subject-assessed ocular redness was also significantly lower with brimonidine (P ≤ 0.0005). No tachyphylaxis was evident. There were few ocular AEs, all mild to moderate in severity, and no redness rebound was observed upon brimonidine discontinuation. There were no effects on any safety measures, and both brimonidine and its vehicle were reported to be very comfortable.

CONCLUSIONS

Brimonidine 0.025% appeared safe, well tolerated, and reduced ocular redness for at least 4 hours. No tachyphylaxis or rebound redness upon treatment discontinuation was observed.

Non-amyloidogenic effects of α2 adrenergic agonists: implications for brimonidine-mediated neuroprotection

The amyloid beta (Aβ) pathway is strongly implicated in neurodegenerative conditions such as Alzheimer's disease and more recently, glaucoma. Here, we identify the α2 adrenergic receptor agonists (α2ARA) used to lower intraocular pressure can prevent retinal ganglion cell (RGC) death via the non-amyloidogenic Aβ-pathway. Neuroprotective effects were confirmed in vivo and in vitro in different glaucoma-related models using α2ARAs brimonidine (BMD), clonidine (Clo) and dexmedetomidine. α2ARA treatment significantly reduced RGC apoptosis in experimental-glaucoma models by 97.7% and 92.8% (BMD, P<0.01) and 98% and 92.3% (Clo, P<0.01)) at 3 and 8 weeks, respectively. A reduction was seen in an experimental Aβ-induced neurotoxicity model (67% BMD and 88.6% Clo, both P<0.01, respectively), and in vitro, where α2ARAs significantly (P<0.05) prevented cell death, under both hypoxic (CoCl₂) and stress (UV) conditions. In experimental-glaucoma, BMD induced ninefold and 25-fold and 36-fold and fourfold reductions in Aβ and amyloid precursor protein (APP) levels at 3 and 8 weeks, respectively, in the RGC layer, with similar results with Clo, and in vitro with all three α2ARAs. BMD significantly increased soluble APPα (sAPPα) levels at 3 and 8 weeks (2.1 and 1.6-fold) in vivo and in vitro with the CoCl₂ and UV-light insults. Furthermore, treatment of UV-insulted cells with an sAPPα antibody significantly reduced cell viability compared with BMD-treated control (52%), co-treatment (33%) and untreated control (27%). Finally, we show that α2ARAs modulate levels of laminin and MMP-9 in RGCs, potentially linked to changes in Aβ through APP processing. Together, these results provide new evidence that α2ARAs are neuroprotective through their effects on the Aβ pathway and sAPPα, which to our knowledge, is the first description. Studies have identified the need for α-secretase activators and sAPPα-mimetics in neurodegeneration; α2ARAs, already clinically available, present a promising therapy, with applications not only to reducing RGC death in glaucoma but also other neurodegenerative processes involving Aβ.

Effects of Systemic Administration of Dexmedetomidine on Intraocular Pressure and Ocular Perfusion Pressure during Laparoscopic Surgery in a Steep Trendelenburg Position: Prospective, Randomized, Double-Blinded Study

Increased intraocular pressure (IOP) during surgery is a risk factor for postoperative ophthalmological complications. We assessed the efficacy of systemically infused dexmedetomidine in preventing the increase in IOP caused by a steep Trendelenburg position, and evaluated the influence of underlying hypertension on IOP during surgery. Sixty patients undergoing laparoscopic surgery in a steep Trendelenburg position were included. Patients in the dexmedetomidine group received a 1.0 µg/kg IV loading dose of dexmedetomidine before anesthesia, followed by an infusion of 0.5 µg/kg/hr throughout the operation. Patients in the saline group were infused with the same volume of normal saline. IOP and ocular perfusion pressure (OPP) were measured 16 times pre- and intraoperatively. In the saline group, IOP increased in the steep Trendelenburg position, and was 11.3 mmHg higher at the end of the time at the position compared with the baseline value (before anesthetic induction). This increase in IOP was attenuated in the dexmedetomidine group, for which IOP was only 4.2 mmHg higher (P < 0.001 vs. the saline group). The steep Trendelenburg position was associated with a decrease in OPP; the degree of decrease was comparable for both groups. In intragroup comparisons between patients with underlying hypertension and normotensive patients, the values of IOP at every time point were comparable. Dexmedetomidine infusion attenuated the increase in IOP during laparoscopic surgery in a steep Trendelenburg position, without further decreasing the OPP. Systemic hypertension did not seem to be associated with any additional increase in IOP during surgery. (Registration at the Clinical Research Information Service of Korea National Institute of Health ID: KCT0001482).

Prevention of neutrophil extravasation by α2-adrenoceptor-mediated endothelial stabilization

Adrenergic receptors are expressed on the surface of inflammation-mediating cells, but their potential role in the regulation of the inflammatory response is still poorly understood. The objectives of this work were to study the effects of α2-adrenergic agonists on the inflammatory response in vivo and to determine their mechanism of action. In two mouse models of inflammation, zymosan air pouch and thioglycolate-induced peritonitis models, the i.m. treatment with xylazine or UK14304, two α2-adrenergic agonists, reduced neutrophil migration by 60%. The α2-adrenergic antagonist RX821002 abrogated this effect. In flow cytometry experiments, the basal surface expression of L-selectin and CD11b was modified neither in murine nor in human neutrophils upon α2-agonist treatment. Similar experiments in HUVEC showed that UK14304 prevented the activation-dependent upregulation of ICAM-1. In contrast, UK14304 augmented electrical resistance and reduced macromolecular transport through a confluent HUVEC monolayer. In flow chamber experiments, under postcapillary venule-like flow conditions, the pretreatment of HUVECs, but not neutrophils, with α2-agonists decreased transendothelial migration, without affecting neutrophil rolling. Interestingly, α2-agonists prevented the TNF-α-mediated decrease in expression of the adherens junctional molecules, VE-cadherin, β-catenin, and plakoglobin, and reduced the ICAM-1-mediated phosphorylation of VE-cadherin by immunofluorescence and confocal analysis and Western blot analysis, respectively. These findings indicate that α2-adrenoceptors trigger signals that protect the integrity of endothelial adherens junctions during the inflammatory response, thus pointing at the vascular endothelium as a therapeutic target for the management of inflammatory processes in humans.

Brimonidine tartrate for the treatment of facial flushing and erythema in rosacea

Rosacea is a chronic inflammatory dermatologic condition that can often be disfiguring with significant negative impact on patients' quality of life. Sanrosa (brimonidine tartate) is a novel therapeutic agent targeting the facial flushing and erythema of rosacea through its α₂ adrenergic receptor agonist activity. The goal of this article is to discuss current treatment options for rosacea and the properties of brimonidine tartate as well as the evidence surrounding its efficacy and safety profile.

Brimonidine in the treatment of glaucoma and ocular hypertension

Treatment in glaucoma aims to lower intraocular pressure (IOP) to reduce the risk of progression and vision loss. The alpha2-adrenergic receptor agonist brimonidine effectively lowers IOP and is useful as monotherapy, adjunctive therapy, and replacement therapy in open-angle glaucoma and ocular hypertension. A fixed combination of brimonidine and timolol, available in some countries, reduces IOP as effectively as concomitant therapy with brimonidine and timolol and offers the convenience of 2 drugs in a single eyedrop. Brimonidine is safe and well tolerated. Its most common side-effects are conjunctival hyperemia, allergic conjunctivitis, and ocular pruritus. The newest formulation of brimonidine, brimonidine-Purite 0.1%, has a higher pH to improve the ocular bioavailability of brimonidine. This formulation contains the lowest effective concentration of brimonidine and is preserved with Purite(R) to enhance ocular tolerability. Brimonidine-Purite 0.1% is as effective in reducing IOP as the original brimonidine 0.2% solution preserved with benzalkonium chloride. Recent results from preclinical and clinical studies suggest that brimonidine may protect retinal ganglion cells and their projections from damage and death independently of its effects on IOP. The potential for neuroprotection with brimonidine is an added benefit of its use in glaucoma and ocular hypertension.

Role of fixed combinations in the management of open-angle glaucoma

The first-line option for lowering intraocular pressure (IOP) is a single hypotensive agent, but patients frequently require additional IOP-lowering agents to reach their target pressures. Disadvantages of this multi-therapy approach include washout effect, inconvenience and poor adherence. Fixed combinations (FCs) combine two or more hypotensive agents in a single bottle, providing a convenient once-daily therapy, which tends to improve adherence. FCs generally offer equivalent efficacy to concomitant use of the individual components, with equivalent or superior tolerability. Studies also show that FCs can be more cost effective than nonfixed combinations. In terms of optimizing IOP control, minimizing visual field deterioration, preventing visual disability and minimizing associated healthcare costs, FCs are an important component of glaucoma management.

Fixed combination of topical brimonidine 0.2% and timolol 0.5% for glaucoma and uncontrolled intraocular pressure

Lowering IOP is the most readily modifiable risk factor to delay the development and progression of glaucoma (POAG). The fixed combination of brimonidine tartrate 0.2% and timolol maleate 0.5% (FCBT) combines a highly selective α2-adrenergic agonist (brimonidine) with a non-selective β-blocker (timolol). FCBT reduces aqueous production and enhances uveoscleral outflow. Concomitant brimonidine and timolol have additive effects on reducing intraocular pressure (IOP). Multi-center randomized control trials have documented superiority of FCBT twice daily on IOP control compared with monotherapy with the individual components, and equal efficacy compared with concomitant therapy. IOP reduction with FCBT versus fixed combination dorzolamide 2% and timolol 0.5% (FCDT) was similar in a small study. Other studies (n > 293) evaluating concomitant brimonidine and timolol have shown that it is not inferior to FCDT. However, concomitant brimonidine and timolol administered twice daily was significantly less efficacious in IOP reduction than fixed combination latanoprost 0.005% and timolol 0.5% (FCLT). There are no published studies comparing FCBT with FCLT. The side effect profile for FCBT reflects that of its individual components. FCBT was generally well tolerated, with less ocular side effects than brimondine alone, but more than timolol alone. Documented systemic effects were few, although this could be confounded by selection bias. FCBT is a safe and effective IOP lowering agent for POAG and ocular hypertension.

Update on the role of alpha-agonists in glaucoma management

Glaucoma is the second most common cause of world blindness (following cataract) with estimated cases reaching 79.6 million by 2020. Although the etiology of glaucoma is multi-factorial, intraocular pressure (IOP) is the only modifiable factor in glaucoma management proven to alter the natural course of the disease. Among various classes of IOP-lowering medications currently available, alpha-adrenergic receptor agonists are used either as monotherapy, as second-line therapy, or in fixed combination with beta-blockers. Non-selective adrenergic agonists such as epinephrine and dipivefrin are infrequently used today for the treatment of glaucoma or ocular hypertension, and have been replaced by the alpha-2-selective agonists. The use of apraclonidine for IOP reduction in glaucoma or OHT is limited due to a high rate of follicular conjunctivitis. The alpha-2-selective agonist in use today is brimonidine. The brimonidine-purite formulations are preferred to brimonidine-benzalkonium chloride (BAC) formulations due better tolerability while maintaining similar efficacy. Brimonidine is also effective when used in combination with a beta-blocker. Using brimonidine-timolol fixed combination (BTFC) as first-line therapy has an added potential for neuroprotection. This would be a valuable strategy for glaucoma treatment, for patients who are intolerant of prostaglandin analogs, or for patients where prostaglandin analogues are contraindicated as first-line therapy, such as in patients with inflammatory glaucoma.

Fixed combinations of dorzolamide-timolol and brimonidine-timolol in the management of glaucoma

IMPORTANCE OF THE FIELD

The emergence of fixed-combination drugs for the treatment of glaucoma has, to some extent, changed the medical management of glaucoma. The potential benefits of these drugs include a reduction in the total number of drops and preservatives instilled per day and improved patient comfort factors, which may contribute to better compliance. Combination medications may also improve therapeutic efficacy and play an important role in controlling medication cost. However, the fixed dosing may be a disadvantage in some cases.

AREA COVERED IN THIS REVIEW

This review describes the composition, pharmacokinetics, mode of action, efficacy, side effects, and safety profile of fixed-combination dorzolamide-timolol and fixed-combination brimonidine-timolol.

WHAT THE READER WILL GAIN

Understanding of the pros, cons, and safety profile of two FDA approved fixed-combination antiglaucoma medication.

TAKE HOME MESSAGE

Fixed-combination medications may be a reasonable adjunct to prostaglandins if a large drop in the intraocular pressure (IOP) is desired and adding only one medication is unlikely to reach the target IOP range. Both mentioned drugs are effective in reducing the IOP and further clinical studies will help identify differences in efficacy between the two. The clinician must make an individualized assessment of the medication's risk-benefit profile for each patient.

Meta-analysis of randomized controlled trials comparing timolol with brimonidine in the treatment of glaucoma

This paper aims to compare the efficacy and tolerability of timolol versus brimonidine in the treatment of glaucoma. Comprehensive searches were performed using Medline, Embase and the Cochrane Controlled Trials Register for randomized controlled trials comparing timolol and brimonidine. Two reviewers independently assessed trials for eligibility and quality and extracted data. A random effects model was used to combine studies. Outcome was defined as the absolute mean intraocular pressure (IOP) reduction from baseline to end-point for efficacy, and relative risk (RR) for adverse events. Subgroup analysis and meta-regression were used to explore heterogeneity according to trial design and quality. Ten publications reporting on eight trials with 2387 participants were included in the meta-analysis. Two further trials were commented on qualitatively. IOP reduction was not significantly different between timolol and brimonidine. Weighted mean difference (WMD) of IOP reduction was 0.24 mmHg (favouring brimonidine) with a 95% confidence interval of -0.57 to 1.04 mmHg. There was significant heterogeneity between studies (chi(2) (13) = 73.75, P < 0.00001, I(2) = 91%). Subgroup analysis showed no significant WMD for studies where data were analysed from end-points >/=6 months or <6 months. Meta-regression analysis showed increased WMD IOP reduction in favour of brimonidine with increased trial quality (t(3) = -4.58, P = 0.01), but no significant association with trial duration (t(3) = 0.73, P = 0.51) or size (t(3) = -0.59, P = 0.57). The RR of ocular allergy was much lower with timolol than brimonidine (RR = 0.08, 95% confidence interval 0.01 to 0.47). Publication bias was not evident on a funnel plot, although the number of studies was small. The conclusion is that both drugs are equally effective in lowering IOP. Brimonidine is associated with a higher rate of allergy.

Reversible cicatricial ectropion precipitated by topical brimonidine eye drops

Bilateral cicatricial ectropian was precipitated by topical brimonidine eye drops. On discontinuation of the drug, the ectropian resolved. Patients on brimonidine who develop cicatricial ectropian should not be managed surgically at first presentation.

The Comparative Cardiovascular, Pulmonary, Ocular Blood Flow, and Ocular Hypotensive Effects of Topical Travoprost, Bimatoprost, Brimonidine, and Betaxolol

OBJECTIVE

This study evaluated systemic and ocular acute safety and intraocular pressure (IOP)-lowering efficacy of travoprost 0.004% and bimatoprost 0.03%, compared to brimonidine 0.2% and betaxolol 0.25% in healthy subjects.

PATIENTS AND METHOD

Nineteen (19) young men, ages between 24 and 42, were enrolled in a single-center, institutional randomized, double-masked, crossover clinical trial. Baseline IOP, heart rate, blood pressure, and respiratory rate were recorded at hour 0. At minute 30, heart rate, blood pressure, respiratory rate, and spirometry were measured. At hour 1, color Doppler imaging of retrobulbar vessels was performed. At hour 2, heart rate, blood pressure, and respiratory rate were measured; spirometry and a 15-minute treadmill test were performed. The same protocol was applied after one drop of a study medication was instilled into each eye on four subsequent visits at 5-day intervals.

RESULTS

Travoprost and bimatoprost did not cause significant reductions in systolic blood pressure during exercise and recovery. The mean respiratory rate and forced expiratory volume in 1 second were not significantly altered by any study medication. Travoprost reduced the resistive index and increased blood velocities in the ophthalmic artery and its branches. Bimatoprost caused a significant increase in end diastolic velocity of the ophthalmic artery. At hour 6, all medications reduced IOP significantly (p < 0.05). The most frequent ocular side effect of travoprost and bimatoprost was conjunctival hyperemia.

CONCLUSION

Travoprost and bimatoprost were found to be systemically safe and caused an increase in blood-flow velocities of the retrobulbar vessels after a single-dose application. Their ocular hypotensive effect was comparable to that of brimonidine and greater than that of betaxolol in healthy subjects.

Adrenoceptor agonist poisoning after accidental oral ingestion of brimonidine eye drops

OBJECTIVE

Brimonidine tartrate is a relatively selective alpha(2) adrenic agonist that lowers elevated intraocular pressure. A 2-yr-old boy presented with severe cardiorespiratory symptoms of systemic alpha(2) adrenergic intoxication after accidentally ingesting 2 mL of brimonidine ophthalmic solution (0.2%) orally. At 20 mins after ingestion, he became acutely pale and lethargic, with shallow infrequent respirations. The symptoms resolved completely within the next 10 hrs.

METHODS

The pharmacokinetics of brimonidine in plasma and urine were analyzed using gas chromatography and mass spectrometry.

RESULTS

Maximum plasma concentrations were 40 ng/mL 5 hrs after ingestion. The plasma elimination half-life value was 2.7 hrs. Elimination via urine was calculated as having a terminal half-life value of 3.2 hrs.

CONCLUSIONS

This case illustrates the ability of brimonidine to gain rapid access to the central nervous system. This first passage is followed by a redistribution phase with rising plasma concentrations. Children who accidentally ingest brimonidine orally should be admitted to a pediatric intensive care unit.

Short posterior ciliary artery, central retinal artery, and choroidal hemodynamics in brimonidine-treated primary open-angle glaucoma patients

PURPOSE

Malfunction in peripapillary hemodynamics has been suggested to play a major part in the pathogenesis of primary open-angle glaucoma (POAG). The aim of this study was to determine whether topically applied brimonidine can influence blood hemodynamic characteristics associated with the perioptic short posterior ciliary arteries (SPCAs), central retinal artery (CRA), and choroidal vascular system in POAG patients.

DESIGN

Randomized clinical trial. In this prospective, institutional, double-masked, vehicle-controlled, randomized clinical trial, the intraocular pressure (IOP) and vascular dynamics of the SPCAs, CRA, and choroidal vascular system were analyzed in both eyes of 17 POAG patients, before and after treatment with 0.2% brimonidine for 4 weeks.

RESULTS

Mean IOP reduction was significant (18.7%) following treatment with brimonidine. However, no clear changes were recorded with respect to blood perfusion parameters (peak systolic velocity, end-diastolic velocity, pulsatility, and resistance indices) associated with the SPCAs and CRA or the choroidal ocular pulse amplitude.

CONCLUSIONS

Topical treatment of brimonidine to POAG patients causes a significant reduction of IOP, but blood hemodynamic properties associated with the SPCAs, CRA, and choroidal vascular systems appeared unaffected. Topically applied brimonidine, therefore, appears not to constrict or dilate peripapillary blood vessels.

Achieving low target pressures with today's glaucoma medications

In the 21st century there are more highly effective medical management options for glaucoma than there were in the 1980s and 1990s. In deciding among them, the clinician's challenge is to select what is clinically relevant from the large amounts of available data. In evaluating different drugs the clinician must consider not only the mean intraocular pressure (IOP) of a trial population, but also the percentage of patients achieving clinically relevant low IOPs. The consistency of IOP control throughout the day and night is also critical. Other factors such as safety, tolerability, and cost-effectiveness must also be kept in mind, with an awareness (both in human and monetary terms) of the cost of treatment failure. This overview concludes that newer medical regimens for IOP lowering address efficacy and safety issues more successfully than older ones.

A 3-month comparison of efficacy and safety of brimonidine-purite 0.15% and brimonidine 0.2% in patients with glaucoma or ocular hypertension

PURPOSE

To compare the efficacy and safety of brimonidine Purite 0.15% (ALPHAGAN P) BID with brimonidine 0.2% (ALPHAGAN) BID in patients with glaucoma or ocular hypertension.

METHODS

3-month, multicenter, randomized, double-masked trial. Eligible patients were taking brimonidine 0.2% BID for at least 6 weeks prior to study entry and their intraocular pressure (IOP) was < or = 21 mm Hg. Patients were randomly assigned to receive either brimonidine Purite 0.15% BID (n = 203) or brimonidine 0.2% BID (n = 204). Scheduled visits were prestudy, baseline, and weeks 2, 6 and 12. IOP was measured at hour 0 and hour 2 to evaluate efficacy. Safety was measured by monitoring adverse events. Patient satisfaction and comfort were also evaluated at all visits.

RESULTS

There was no statistically significant difference between the brimonidine 0.2% and brimonidine Purite 0.15% groups with respect to mean IOP at baseline. The IOP-lowering efficacy of brimonidine Purite 0.15% was equivalent to that of brimonidine 0.2% and both study treatments maintained IOP-lowering effects of brimonidine 0.2%. There were no significant between-group differences in mean IOP. The differences in the mean IOPs were < or = 0.26 mm Hg and the mean change from baseline IOP was < or = 0.35 mm Hg at all follow-up time points. There were no statistically significant differences between the two groups in the overall incidence of adverse events. The most commonly reported treatment-related adverse events were conjunctival hyperemia and allergic conjunctivitis: both were mild in severity.

CONCLUSION

Brimonidine Purite 0.15% dosed BID provides equal IOP-lowering efficacy to brimonidine 0.2% BID. Patients previously controlled on brimonidine 0.2% can be successfully switched to brimonidine Purite 0.15%.

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.

Twelve-month evaluation of brimonidine-purite versus brimonidine in patients with glaucoma or ocular hypertension

PURPOSE

To compare the efficacy and safety of brimonidine-Purite (Alphagan; Allergan, Irvine, CA) 0.15% and 0.2% three times daily with brimonidine (Alphagan) 0.2% three times daily in patients with glaucoma or ocular hypertension.

PATIENTS AND METHODS

In this 12-month, randomized, multicenter, double-masked, parallel-group study, patients were randomly assigned to receive brimonidine-Purite 0.15% (n = 381), brimonidine-Purite 0.2% (n = 383), or brimonidine 0.2% (n = 383) three times daily. Visits were conducted before the study, at baseline, at weeks 2 and 6, and at months 3, 6, 9, and 12. Diurnal intraocular pressure was measured at 8 am, 10 am, 3 pm, and 5 pm at baseline, week 6, and at months 3, 6, and 12. Intraocular pressure was also measured at 8 and 10 am at week 2 and month 9. Safety was evaluated by adverse events and other ocular and systemic measures.

RESULTS

At baseline, mean intraocular pressure was similar in the three treatment groups. During follow-up, there were no statistically significant among-group differences in mean intraocular pressure or mean changes from baseline intraocular pressure (at peak or trough). The difference in mean intraocular pressure between the brimonidine-Purite-0.15% and brimonidine-0.2% treatment group was less than 1 mm Hg at all time points. The relative percent difference in allergic conjunctivitis was 41% lower in the brimonidine-Purite 0.15% group compared with the brimonidine 0.2% group. The comfort and satisfaction rating significantly favored brimonidine-Purite 0.15%.

CONCLUSIONS

Over 12-months, brimonidine-Purite 0.15% and 0.2% provided intraocular pressure lowering comparable with brimonidine 0.2% in patients with glaucoma or ocular hypertension. Brimonidine-Purite 0.15% showed the most favorable safety and tolerability profile with a reduced incidence of allergic conjunctivitis and better satisfaction and comfort rating.

Neuroprotective effects of brimonidine against transient ischemia-induced retinal ganglion cell death: a dose response in vivo study

The purpose of this study was to investigate the dose-response effects of topically administered brimonidine (BMD) on retinal ganglion cell (RGC) survival, short and long periods of time after transient retinal ischemia. In adult Sprague-Dawley rats, RGCs were retrogradely labeled with the fluorescent tracer fluorogold (FG) applied to both superior colliculi. Seven days later, the left ophthalmic vessels were ligated for 90 min. One hr prior to retinal ischemia, two 5 microl drops of saline alone or saline containing 0.0001, 0.001, 0.01 or 0.1% BMD were instilled on the left eye. Rats were processed 7, 14 or 21 days later and densities of surviving RGCs were estimated by counting FG-labeled RGCs in 12 standard regions of each retina. The following have been found. (1) Seven days after 90 min of transient ischemia there is loss of approximately 46% of the RGC population. (2) topical pre-treatment with BMD prevents ischemia-induced RGC death in a dose-dependent manner. Administration of 0.0001% BMD resulted in the loss of approximately 37% of the RGC population and had no significant neuroprotective effects. Administration of higher concentrations of BMD (0.001 or 0.01%) resulted in the survival of 76 or 90%, respectively, of the RGC population, and 0.1% BMD fully prevented RGC death in the first 7 days after ischemia. (3) Between 7 and 21 days after ischemia there was an additional slow cell loss of approximately 25% of the RGC population. Pre-treatment with 0.1% BMD also reduced significantly this slow cell death. These results indicate that the neuroprotective effects of BMD, when administered topically, are dose-dependent and that the 0.1% concentration achieves optimal neuroprotective effects against the early loss of RGCs. Furthermore, this concentration is also effective to diminish the protracted loss of RGCs that occurs with time after transient ischemia.

Pharmacodynamics of citicoline relevant to the treatment of glaucoma

Citicoline (exogenous CDP-choline) is a nontoxic and well-tolerated drug used in pharmacotherapy of brain insufficiency and some other neurological disorders, such as stroke, brain trauma, and Parkinson's disease. A few reports indicate that citicoline treatment may also be beneficial in glaucoma. Currently glaucoma is considered a neurodegenerative disease in which retinal ganglion cells (RGC) slowly die, likely in the apoptotic mechanism. Endogenous CDP-choline is a natural precursor of cellular synthesis of phospholipids, mainly phosphatydylcholine (PtdCho). Enhancement of PtdCho synthesis may counteract neuronal apoptosis and provide neuroprotection. Citicoline, when administered, undergoes a quick transformation to cytidine and choline, which are believed to enter brain cells separately and provide neuroprotection by enhancing PtdCho synthesis; similar effect may be expected to occur in glaucomatous RGC. Furthermore, citicoline stimulates some brain neurotransmitter systems, including the dopaminergic system, and dopamine is known as a major neurotransmitter in retina and postretinal visual pathways. In a double-blind, placebo-controlled study, treatment of glaucoma resulted in functional improvement in the visual system noted with electrophysiological methods. Development of citicoline as a treatment for glaucoma is indicated.

A comparison of the efficacy and tolerability of brimonidine and latanoprost in adults with open-angle glaucoma or ocular hypertension: a three-month, multicenter, randomized, double-masked, parallel-group trial

BACKGROUND

Many physicians recommend either brimonidine or latanoprost as firstline therapy for chronic open-angle glaucoma or ocular hypertension. However, a search of MEDLINE indicates that there have been few head-to-head comparisons of the 2 monotherapies in a clinical setting.

OBJECTIVE

This study compared the clinical efficacy and tolerability of brimonidine 0.2% twice daily with those of latanoprost 0.005% once daily as monotherapy in patients with open-angle glaucoma or ocular hypertension.

METHODS

In this 3-month, multicenter, double-masked, parallel-group, 4-visit study, treatment-naive and previously treated patients with open-angle glaucoma or ocular hypertension and bilateral intraocular pressure (IOP) after washout of between 22 and 34 mm Hg were randomized to receive either brimonidine or latanoprost. Patients who had received previous treatment with either study drug were excluded from the study. The primary outcome measure was response rate, defined as the percentage of patients achieving > or = 20% reduction in IOP from baseline to month 3. Secondary outcome measures were mean IOP reduction from baseline to month 3 and clinical success, defined as the investigator's recommendation that the patient continue using the assigned study medication.

RESULTS

A total of 127 patients (55 treatment naive) were enrolled, 66 in the brimonidine group and 61 in the latanoprost group. After 3 months of treatment, 80% of patients in the brimonidine group and 74% of patients in the latanoprost group had achieved > or = 20% reduction in IOP from baseline. The mean reduction in IOP from baseline at month 3 was 6.8 mm Hg with brimonidine and 6.5 mm Hg with latanoprost (27.8% vs 27.0%, respectively). Among treatment-naive patients, a significantly higher percentage of brimonidine-treated patients achieved > or = 20% decrease in IOP compared with latanoprost-treated patients (88% vs 59%, respectively; P = 0.01). In previously treated patients, a higher percentage of the latanoprost group achieved > or = 20% reduction in IOP compared with the brimonidine group (88% vs 74%, respectively); however, the difference was not statistically significant. Significantly more patients in the brimonidine group achieved clinical success at month 3 compared with patients in the latanoprost group (91% vs 74%; P = 0.01).

CONCLUSIONS

At peak effect, brimonidine twice daily was as effective as latanoprost once daily in lowering IOP. In treatment-naive patients, latanoprost was associated with a significantly higher rate of nonresponse after 3 months of treatment compared with brimonidine. This suggests that brimonidine may be the more reliable choice for first-line therapy of newly diagnosed open-angle glaucoma or ocular hypertension. In previously treated patients, however, latanoprost provided greater mean IOP reduction than did brimonidine. Significantly more patients achieved clinical success with brimonidine monotherapy than with latanoprost monotherapy.

Safety and efficacy of brimonidine in children with glaucoma

PURPOSE

Brimonidine is a relatively selective alpha-agonist, which reduces intraocular pressure (IOP) by decreasing aqueous production and increasing uveoscleral outflow. Brimonidine passes through the blood-brain barrier, potentially causing central nervous system (CNS) toxicity. There have been reports of bradycardia, hypotension, hypothermia, hypotonia, and apnea in infants after topical brimonidine.

METHODS

We reviewed the IOP data and side effects of children at the Duke University Eye Center placed on brimonidine from June 1997 to October 2000. Brimonidine 0.2% was used for patients whose glaucoma was uncontrolled on maximal tolerated medical therapy. A monocular trial was performed whenever possible, and brimonidine was not prescribed for infants. Included were 32 eyes of 30 patients with uncontrolled IOP and varied glaucoma diagnoses.

RESULTS

The mean patient age was 10.5 years, with a mean follow-up on brimonidine of 10.8 months. Most patients were on other glaucoma medications. In 11 of the 32 eyes the IOP data could be interpreted, and in these eyes the IOP decreased from a mean of 22.5 +/- 4.9 mm Hg to a mean of 20.8 +/- 4.0 mm Hg (a mean decrease of 6.7% +/- 10%, P =.04) on brimonidine after a mean follow-up of 11.0 +/- 6.9 months. Two young children (ages 2.4 and 3.7 years) repeatedly were unarousable soon after the administration of brimonidine. Five other children experienced extreme fatigue after brimonidine administration. All symptoms resolved after brimonidine was discontinued.

DISCUSSION/CONCLUSIONS

Brimonidine should be used with caution in young children because of the potential for CNS depression. In selected patients, brimonidine has a substantial ocular hypotensive effect.

Brimonidine (Alphagan): a clinical profile four years after launch

The early information on the clinical efficacy, safety, and tolerability of brimonidine 0.2% were obtained from studies that compared brimonidine monotherapy with timolol and betaxolol. These studies showed its intra-ocular pressure lowering efficacy to be comparable with timolol and superior to betaxolol. The data from the timolol studies showed consistent results after four years. These findings have been confirmed by additional studies in the clinical setting. More recently, several clinical trials have been completed investigating the role of brimonidine as adjunctive medication to beta-blockers and as replacement therapy to other intraocular pressure lowering compounds. When added to beta-blockers, brimonidine is superior to dorzolamide, similar in efficacy but better tolerated than pilocarpine, and more predictable than latanoprost. Data from replacement studies have indicated that there may be advantages in replacing rather than adding medications in the treatment of glaucoma.

Effectiveness and safety of brimonidine as adjunctive therapy for patients with elevated intraocular pressure in a large, open-label community trial

PURPOSE

To determine the effectiveness and safety of brimonidine when used in combination with one or more glaucoma medications in patients with glaucoma or ocular hypertension.

METHODS

Post hoc analysis of a multicenter, 2-month, open-label, prospective, clinical trial in which 2,335 patients received brimonidine as monotherapy, replacement therapy, or combination therapy. Patients who received brimonidine as combination therapy (n = 554) were examined in the current analysis. Efficacy was determined by the reduction in intraocular pressure (IOP) from baseline before the addition of brimonidine. Safety and tolerability parameters included adverse events and quality-of-life measures (e.g., ocular comfort, energy level, breathing ability, night vision).

RESULTS

Addition of brimonidine to preexisting regimens resulted in an overall mean additional reduction in IOP of 17.9% (4.26 mm Hg) at month 2 (P < 0.001). Significant additional IOP lowering was provided by brimonidine in combination with each preexisting regimen evaluated (P < or = 0.061). When brimonidine was added to monotherapy with a nonselective beta-blocker, the mean additional IOP reduction was 15.5% (3.61 mm Hg, P < 0.001). Addition of brimonidine to latanoprost monotherapy provided a 32.2% (5.89 mm Hg) mean additional IOP reduction (P < 0.001). Addition of brimonidine to combination regimens that included latanoprost provided additional mean decreases in LOP ranging from 15.5% (3.63 mm Hg, P < 0.002) to 20.1% (6.62 mm Hg, P < 0.001). All quality-of-life parameters remained high or improved during the study. Mild to moderate adverse events were reported in 5.23% of patients (29 of 552); 98.1% of physicians rated brimonidine adjunctive therapy as good or excellent.

CONCLUSIONS

Brimonidine, when added to existing glaucoma regimens, safely and effectively lowered IOP in this community-based trial.