Combination of brinzolamide and brimonidine for glaucoma and ocular hypertension: critical appraisal and patient focus

Pharmacological Profile and Ocular Hypotensive Effects of Cromakalim Prodrug 1, a Novel ATP-Sensitive Potassium Channel Opener, in Normotensive Dogs and Nonhuman Primates

Purpose: To evaluate pharmacokinetic parameters and ocular hypotensive effects of cromakalim prodrug 1 (CKLP1) in normotensive large animal models. Methods: Optimal CKLP1 concentration was determined by dose response and utilized in short- (5-8 days) and long-term (60 days) evaluation in hound dogs (n = 5) and African Green Monkeys (n = 5). Blood pressure was recorded 3-5 times per week with a tail cuff. Concentrations of CKLP1 and the parent compound levcromakalim were assessed in hound dog plasma and select tissues by LC-MS/MS after bilateral ocular treatment with CKLP1 for 8 days. Pharmacokinetic parameters were calculated from days 1, 4, and 8 data. After necropsy, histology was assessed in 43 tissue samples from each animal. Results: In hound dogs and African Green monkeys, 10 mM CKLP1 (optimal concentration) significantly lowered intraocular pressure (IOP) by 18.9% ± 1.1% and 16.7% ± 6.7%, respectively, compared with control eyes (P < 0.05). During treatment, no significant change in systolic or diastolic blood pressure was observed in either species (P > 0.1). Average values for half-life of CKLP1 was 295.3 ± 140.4 min, Cmax, 10.5 ± 1.6 ng/mL, and area under the concentration vs. time curve (AUClast) 5261.4 ± 918.9 ng·min/mL. For levcromakalim, average values of half-life were 96.2 ± 27 min, Cmax 1.2 ± 0.2 ng/mL, and AUClast 281.2 ± 110.8 ng·min/mL. No significant pathology was identified. Conclusions: CKLP1 lowered IOP in hound dogs and African green monkeys with no effect on systemic blood pressure. Ocular topical treatment of CKLP1 showed excellent tolerability even after extended treatment periods.

A comparative study on the efficacy of brinzolamide/timolol versus brinzolamide/brimonidine fixed drug combinations in primary open-angle glaucoma

Background

To compare the efficacy of brinzolamide 1%/timolol 0.5% fixed drug combination (BTFC) with brinzolamide 1%/brimonidine 0.2% fixed drug combination (BBFC) among the patients with primary open-angle glaucoma (POAG).

Results

The treatment with BTFC in the Group A subjects showed a significant decrease in the intraocular pressure (p = 0.0355*) and a significant increase in the central corneal thickness (p = 0.0087*). Similarly, in the Group B subjects, the treatment with BBFC showed a significant decrease in the intraocular pressure (p = 0.0327*) and a significant increase in the central corneal thickness (p = 0.0227*). In the process of comparing both the fixed drug combinations, there was no significant difference observed in the aspect of efficacy between both the groups in the decrease of intraocular pressure (p = 0.7100) and in the increase of central corneal thickness (p = 0.4077).

Conclusion

Both the fixed drug combinations almost showed a similar efficacy in treating the respective groups, and there is no significant difference observed in the aspect of efficacy between both the fixed drug combinations in decreasing the intraocular pressure and in increasing the central corneal thickness.

Comparison of the Intraocular Pressure-Lowering Efficacy and Safety of the Brinzolamide/Brimonidine Fixed-Dose Combination versus Concomitant Use of Brinzolamide and Brimonidine for Management of Open-Angle Glaucoma or Ocular Hypertension

Objective

To demonstrate that the intraocular pressure (IOP)-lowering efficacy of a twice-daily brinzolamide 10 mg/mL (BRINZ)/brimonidine 2 mg/mL (BRIM) fixed-dose combination (BBFC) was non-inferior to its individual components (BRINZ+BRIM) dosed concomitantly in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT). Safety was also evaluated.

Methods and Analysis

This was a Phase III, multicenter, observer-masked study in patients from China, Russia and Taiwan. Patients aged ≥18 years with a mean IOP ≥21 mmHg and ≤36 mmHg in the same eye after washout of other IOP-lowering medications were included. Eligible patients were randomized (1:1) to receive BBFC or BRIZ+BRIM eye drops twice daily for 3 months. The primary endpoint was the mean change in diurnal IOP (averaged over 09:00, +2 h, and +7 h) from baseline to Month 3. Adverse events (AEs) were recorded throughout the study.

Results

The per-protocol set included 349 patients (BBFC, n=172; BRINZ+BRIM, n=177). The mean±standard deviation diurnal IOP at baseline was 24.6±2.66 mmHg in both groups. At Month 3, the least square mean±standard error change in diurnal IOP from baseline was −7.2±0.34 mmHg and −7.3±0.34 mmHg with BBFC and BRINZ+BRIM, respectively (between-group difference: 0.1 mmHg [95% CI −0.5, 0.7]). In the BBFC and BRINZ+BRIM groups, 53.3% and 55.0% of patients achieved a diurnal IOP <18 mmHg, and 43.2% and 37.4% of patients, respectively, achieved a mean diurnal IOP reduction >30% from baseline at Month 3. Ocular AEs were reported in 28.7% (BBFC) and 22.5% (BRINZ+BRIM) of patients; conjunctival hyperemia was the most frequent ocular AE (BBFC, 6.4%; BRINZ+BRIM, 6.8%). Non-ocular AEs were reported in 32.4% (BBFC) and 30.4% (BRINZ+BRIM) of patients.

Conclusion

The study findings demonstrate that the efficacy of twice-daily BBFC was non-inferior to BRINZ+BRIM in patients with OAG/OHT. The safety profile of BBFC was similar to that of BRINZ+BRIM.

Real-life experience of using brinzolamide/brimonidine fixed drop combination in a tertiary glaucoma centre

PURPOSE

To investigate the intraocular pressure (IOP)-lowering efficacy and tolerance of brinzolamide/brimonidine fixed combination (BBFC) under real-life conditions in a tertiary glaucoma centre.

METHODS

Medical records of all ocular hypertensive and open-angle glaucoma patients (n = 52) treated with BBFC were retrospectively analysed.

RESULTS

Thirty-nine patients had primary open-angle, 6 exfoliative, 2 pigment, 1 normal tension and 1 juvenile open-angle glaucoma and 3 ocular hypertension. The prior therapy was a prostaglandin analogue (PG) (n = 4), PG/timolol (n = 20), PG/timolol and topical carbonic anhydrase inhibitor (CAI; n = 19), timolol/CAI (n = 1), PG and CAI (n = 4), timolol/pilocarpine and PG (n = 1), timolol/brimonidine and PG (n = 1) and timolol/brimonidine, PG and CAI (n = 2). These were simplified to PG/timolol and BBFC (n = 41), PG and BBFC (n = 9), timolol and BBFC (n = 1) and timolol/pilocarpine, PG and BBFC (n = 1). The IOP on the study eyes was 21.2 ± 3.7 mmHg before and 16.9 ± 2.6, 16.0 ± 2.2, 17.6 ± 3.1 and 18.0 ± 3.1 mmHg after the introduction of BBFC at month 1, 3, 6 and 12, respectively (p < 0.0003 for all time points compared to baseline, p = 1.0 for all other comparisons). Thirty-one patients (59.6%) experienced no adverse event, 17 (32.7%) reported ocular and 6 (11.5%) systemic adverse events. BBFC therapy was terminated on 27 patients (51.9%): on 19 (36.5%) due to adverse events and on 8 (15.4%) due to insufficient IOP reduction.

CONCLUSION

In real-life practice, the introduction of BBCF allows significant and clinically meaningful IOP reduction and therapy simplification in glaucoma patients requiring complex medication, but in more than one third of the patients it is not tolerated due to adverse events.

Current management of glaucoma

Glaucoma is an irreversible progressive optic neuropathy, for which the major proven treatment is to lower the intraocular pressure (IOP). Five groups of IOP-lowering eye drops have varying mechanisms of action. Some drops, such as β-blockers and α-2 agonists, have potentially serious systemic side effects. Acetazolamide is the only available oral agent; it is effective at lowering IOP, but significant side effects relegate its use usually to refractory glaucoma. Two new eye drops, netarsudil and latanoprostene bunod, have recently been approved by the United States Food and Drug Administration. Both have novel IOP-lowering mechanisms and target the conventional aqueous outflow system. Selective laser trabeculoplasty is a gentle treatment that enhances conventional aqueous outflow. It may be used as an initial treatment, as a substitute for eye drops, or to delay glaucoma drainage surgery. Recent advancements in glaucoma surgery have seen an influx of minimally invasive glaucoma surgery devices, which are being used more frequently and earlier on in the treatment paradigm. As limited long term data are available, trabeculectomy remains the gold standard IOP-lowering procedure. Improvements in drug delivery are on the horizon. Drug-eluting devices and implants are able to deliver the drug closer to the receptors for an extended period of time. This will improve treatment adherence and efficacy, which are major limitations with current medical therapy.

Ocular hypotensive effect of fixed-combination brinzolamide/brimonidine adjunctive to a prostaglandin analog: a randomized clinical trial

Purpose

To determine whether intraocular pressure (IOP) lowering with fixed-combination brinzolamide/brimonidine (BBFC) adjunctive to a prostaglandin analog (PGA) was superior to that of vehicle+PGA in patients with open-angle glaucoma or ocular hypertension who were inadequately controlled with PGA monotherapy

Methods

This 6-week, multicenter, randomized, double-masked, parallel-group trial was conducted at 30 clinical sites in the United States between October 2013 and May 2014. Eligible patients were adults with open-angle glaucoma or ocular hypertension and with mean IOP ≥21 and <32 mm Hg, whereas receiving an open-label PGA (latanoprost, bimatoprost, or travoprost). Patients instilled a PGA once-daily in a run-in phase before randomization to masked BBFC or vehicle adjunctive treatment. Masked treatments were instilled 3 times daily for 6 weeks, and patients continued once-daily use of their PGA. The primary efficacy end point was the between-group difference in mean diurnal IOP (average of 0800, 1000, 1500, and 1700 hours time points) at week 6.

Results

At week 6, mean diurnal IOP with BBFC+PGA was lower than with vehicle+PGA (17.1±0.4 mm Hg vs 20.5±0.4 mm Hg; between-group difference, −3.4±0.5 mm Hg; P<0.0001; 95% confidence interval, −4.5 to −2.4 mm Hg). BBFC+PGA reduced mean diurnal IOP by 5.7 mm Hg (25%) from the baseline IOP achieved with PGA monotherapy.

Conclusions

Therapy with BBFC produced an additive IOP-lowering effect compared with a PGA alone or in conjunction with vehicle. BBFC may provide an effective treatment option for patients receiving PGA monotherapy who require additional IOP reduction.

ATP sensitive potassium channel openers: A new class of ocular hypotensive agents

ATP sensitive potassium (K_ATP) channels connect the metabolic and energetic state of cells due to their sensitivity to ATP and ADP concentrations. K_ATP channels have been identified in multiple tissues and organs of the body including heart, pancreas, vascular smooth muscles and skeletal muscles. These channels are obligatory hetero-octamers and contain four sulfonylurea (SUR) and four potassium inward rectifier (K_ir) subunits. Based on the particular type of SUR and K_ir present, there are several tissue specific subtypes of K_ATP channels, each with their own unique set of functions. Recently, K_ATP channels have been reported in human and mouse ocular tissues. In ex vivo and in vivo model systems, K_ATP channel openers showed significant ocular hypotensive properties with no appearance of toxic side effects. Additionally, when used in conjunction with known intraocular pressure lowering drugs, an additive effect on IOP reduction was observed. These K_ATP channel openers have also been reported to protect the retinal ganglion cells during ischemic stress and glutamate induced toxicity suggesting a neuroprotective property for this drug class. Medications that are currently used for treating ocular hypertensive diseases like glaucoma do not directly protect the affected retinal cells, are sometimes ineffective and may show significant side effects. In light of this, K_ATP channel openers with both ocular hypotensive and neuroprotective properties, have the potential to develop into a new class of glaucoma therapeutics.

Efficacy and tolerability of brinzolamide/brimonidine suspension and prostaglandin analogs in patients previously treated with dorzolamide/timolol solution and prostaglandin analogs

OBJECTIVE

Fixed combination glaucoma medication is increasingly used in glaucoma treatment. There is a lack of comparative study in the literature of non-beta blocker combination agents used adjunctively with a glaucoma agent in a different class. The objective of this study is to evaluate the effect of intraocular pressure (IOP) control and tolerability of non-beta blocker combination suspension with prostaglandin analogs (PGA) in patients with open angle glaucoma who were previously treated with beta blocker combination solution with PGA.

DESIGN

Open-label retrospective review of patient records.

PATIENTS AND METHODS

This study looked at patients with open angle glaucoma taking dorzolamide/timolol solution with PGA that were switched to brinzolamide/brimonidine combination suspension with PGA. This study reviewed the charts of all patients who were at least 21 years old with a clinical diagnosis of open-angle glaucoma or ocular hypertension in at least one eye. Patients needed to have been treated with concomitant use of PGA and dorzolamide/timolol solution for at least one month. Patients using dorzolamide/timolol solution plus PGA with medication related ocular irritation were switched to brinzolamide/brimonidine suspension with the same PGA. Best-corrected visual acuity, ocular hyperemia grading, slit lamp biomicroscopy and Goldmann applanation tonometry measurements, and patient medication preferences were assessed at baseline, 1 month and 3 months.

RESULTS

Forty eyes with open angle glaucoma. The mean age of the patients was 68 and 60% were females. The IOP before the switch was 17.2 and 16.5 (P=0.70) following the switch at 3 months. We found a decreasing trend of ocular hyperemia (P=0.064) and strong preference (P=0.011) for non-beta blocker combination suspension but no difference of visual acuity and slit lamp findings.

CONCLUSION

Brinzolamide/brimonidine combination suspension when used adjunctively with PGA is equally effective. Patients in this study reported greatly reduced ocular redness and shorter duration of stinging with non-beta blocker combination suspension. Their preference of it over dorzolamide/timolol combination solution makes it a viable treatment option, particularly for the aging glaucoma patient with comorbidities that restrict the beta blocker use.

Ocular Hypotensive Effects of the ATP-Sensitive Potassium Channel Opener Cromakalim in Human and Murine Experimental Model Systems

Elevated intraocular pressure (IOP) is the most prevalent and only treatable risk factor for glaucoma, a leading cause of irreversible blindness worldwide. Unfortunately, all current therapeutics used to treat elevated IOP and glaucoma have significant and sometimes irreversible side effects necessitating the development of novel compounds. We evaluated the IOP lowering ability of the broad spectrum KATP channel opener cromakalim. Cultured human anterior segments when treated with 2 μM cromakalim showed a decrease in pressure (19.33 ± 2.78 mmHg at 0 hours to 13.22 ± 2.64 mmHg at 24 hours; p<0.001) when compared to vehicle treated controls (15.89 ± 5.33 mmHg at 0 h to 15.56 ± 4.88 mmHg at 24 hours; p = 0.89). In wild-type C57BL/6 mice, cromakalim reduced IOP by 18.75 ± 2.22% compared to vehicle treated contralateral eyes (17.01 ± 0.32 mmHg at 0 hours to 13.82 ± 0.37 mmHg at 24 hours; n = 10, p = 0.002). Cromakalim demonstrated an additive effect when used in conjunction with latanoprost free acid, a common ocular hypotensive drug prescribed to patients with elevated IOP. To examine KATP channel subunit specificity, Kir6.2(-/-) mice were treated with cromakalim, but unlike wild-type animals, no change in IOP was noted. Histologic analysis of treated and control eyes in cultured human anterior segments and in mice showed similar cell numbers and extracellular matrix integrity within the trabecular meshwork, with no disruptions in the inner and outer walls of Schlemm's canal. Together, these studies suggest that cromakalim is a potent ocular hypotensive agent that lowers IOP via activation of Kir6.2 containing KATP channels, its effect is additive when used in combination with the commonly used glaucoma drug latanoprost, and is not toxic to cells and tissues of the aqueous humor outflow pathway, making it a candidate for future therapeutic development.

Pharmacotherapy of glaucoma

Glaucoma is a group of diseases involving the optic nerve and associated structures, which is characterized by progressive visual field loss and typical changes of the optic nerve head (ONH). The only known treatment of the disease is reduction of intraocular pressure (IOP), which has been shown to reduce glaucoma progression in a variety of large-scale clinical trials. Nowadays, a relatively wide array of topical antiglaucoma drugs is available, including prostaglandin analogues, carbonic anhydrase inhibitors, beta-receptor antagonists, adrenergic agonists, and parasympathomimetics. In clinical routine, this allows for individualized treatment taking risk factors, efficacy, and safety into account. A major challenge is related to adherence to therapy. Sustained release devices may help minimize this problem but are not yet available for clinical routine use. Another hope arises from non-IOP-related treatment concepts. In recent years, much knowledge has been gained regarding the molecular mechanisms that underlie the disease process in glaucoma. This also strengthens the hope that glaucoma therapy beyond IOP lowering will become available. Implementing this concept with clinical trials remains, however, a challenge.