Bimatoprost/timolol: a review of its use in glaucoma and ocular hypertension

Combination therapy and co-delivery strategies to optimize treatment of posterior segment neurodegenerative diseases

Neurodegenerative diseases affecting the posterior segment of the eye are one of the major causes of irreversible blindness worldwide. The pathogenesis of these retinal pathologies is characterized by a multifactorial etiology, involving the complex interaction of different apoptotic mechanisms, suggesting that effective treatments will require a multimodal approach. Thus, combination therapy based on the potential synergistic activities of drugs with different mechanisms of action is currently receiving considerable attention. Here, we summarize several kinds of strategy for the co-administration of different drugs to the posterior segment of the eye, highlighting those that involve co-delivery from multiloaded drug delivery systems.

Effect of Cromakalim Prodrug 1 (CKLP1) on Aqueous Humor Dynamics and Feasibility of Combination Therapy With Existing Ocular Hypotensive Agents

Purpose

Cromakalim prodrug 1 (CKLP1) is a water-soluble ATP-sensitive potassium channel opener that has shown ocular hypotensive properties in ex vivo and in vivo experimental models. To determine its mechanism of action, we assessed the effect of CKLP1 on aqueous humor dynamics and in combination therapy with existing ocular hypotensive agents.

Methods

Outflow facility was assessed in C57BL/6 mice by ex vivo eye perfusions and by in vivo constant flow infusion following CKLP1 treatment. Human anterior segments with no trabecular meshwork were evaluated for effect on pressure following CKLP1 treatment. CKLP1 alone and in combination with latanoprost, timolol, and Rho kinase inhibitor Y27632 were evaluated for effect on intraocular pressure in C57BL/6 mice and Dutch-belted pigmented rabbits.

Results

CKLP1 lowered episcleral venous pressure (control: 8.9 ± 0.1 mm Hg versus treated: 6.2 ± 0.1 mm Hg, P < 0.0001) but had no detectable effect on outflow facility, aqueous humor flow rate, or uveoscleral outflow. Treatment with CKLP1 in human anterior segments without the trabecular meshwork resulted in a 50% ± 9% decrease in pressure, suggesting an effect on the distal portion of the conventional outflow pathway. CKLP1 worked additively with latanoprost, timolol, and Y27632 to lower IOP, presumably owing to combined effects on different aspects of aqueous humor dynamics.

Conclusions

CKLP1 lowered intraocular pressure by reducing episcleral venous pressure and lowering distal outflow resistance in the conventional outflow pathway. Owing to this unique mechanism of action, CKLP1 works in an additive manner to lower intraocular pressure with latanoprost, timolol, and Rho kinase inhibitor Y27632.

Upregulation of Homer1a Promoted Retinal Ganglion Cell Survival After Retinal Ischemia and Reperfusion via Interacting with Erk Pathway

Retinal ischemia and reperfusion (I/R) is extensively involved in ocular diseases, causing retinal ganglion cell (RGCs) death resulting in visual impairment and blindness. Homer1a is considered as an endogenous neuroprotective protein in traumatic brain injury. However, the roles of Homer1a in RGCs I/R injury have not been elucidated. The present study investigated the changes in expression and effect of Homer1a in RGCs both in vitro and in vivo after I/R injury using Western blot, TUNEL assay, gene interference and overexpression, and gene knockout procedures. The levels of Homer1a and phosphorylated Erk (p-Erk) increased in RGCs and retinas after I/R injury. Upregulation of Homer1a in RGCs after I/R injury decreased the level of p-Erk, and mitigated RGCs apoptosis. Conversely, downregulation of Homer1a increased the level of p-Erk, and augmented RGCs apoptosis. Furthermore, inhibition of the p-ERK reduced RGCs apoptosis, and increased the expression of Homer 1a after I/R injury. Finally, the retinas of Homer1a KO mice treated with I/R injury had significantly less dendrites and RGCs, compared with Homer1a WT mice. These findings demonstrated that Homer1a may contribute to RGCs survival after I/R injury by interacting with Erk pathway.

Efficacy of a preservative-free formulation of fixed-combination bimatoprost and timolol (Ganfort PF) in treatment-naïve patients vs previously treated patients

PURPOSE

To evaluate, using subgroup analysis, the effect of treatment status on the intraocular pressure (IOP)-lowering efficacy of a preservative-free formulation of fixed-combination bimatoprost 0.03%/timolol 0.5% (FCBT PF).

METHODS

A primary, multicenter, randomized, double-masked, 12-week study compared the efficacy and safety of FCBT PF with preserved FCBT (Ganfort(®)) in 561 patients diagnosed with glaucoma or ocular hypertension. For this analysis, eligible patients were treatment-naïve or had inadequate IOP lowering and underwent a washout of previous treatment. IOP (8 am, 10 am, and 4 pm) was measured at baseline and weeks 2, 6, and 12. Subgroup analysis of the FCBT PF arm assessed changes in average eye IOP from baseline in treatment-naïve vs previously treated patients. To evaluate the effect of treatment status at baseline (treatment-naïve vs previously treated) on IOP reduction in the FCBT PF treatment group, an analysis of covariance model was used with treatment status and investigator as fixed effects, and baseline average eye IOP, age, glaucoma diagnosis, and baseline average eye corneal thickness as covariates. P-values and the 95% confidence intervals were determined using the model.

RESULTS

In the FCBT PF arm, IOP mean changes from baseline ranged from -8.7 mmHg to -9.8 mmHg in treatment-naïve patients (N=50), compared with -7.3 mmHg to -8.5 mmHg in previously treated patients (N=228). Baseline IOP, age, glaucoma diagnosis, and corneal thickness significantly affected IOP reduction in the FCBT PF group. Adjusting for these covariates, FCBT PF had a greater IOP-lowering effect (0.8-1.7 mmHg) in treatment-naïve patients than previously treated patients, which was statistically significant (P≤0.05) at seven of nine time points.

CONCLUSION

In this subgroup analysis, FCBT PF reduced IOP more effectively in treatment-naïve than in previously treated patients possibly due, in part, to altered responsiveness or tachyphylaxis that has been associated with prior ocular hypotensive agent treatment.

Efficacy and tolerability of fixed-combination bimatoprost/timolol versus fixed-combination dorzolamide/brimonidine/timolol in patients with primary open-angle glaucoma or ocular hypertension: a multicenter, prospective, crossover study

BACKGROUND

Fixed-combination ocular hypotensives have multiple advantages, but triple-therapy dorzolamide/brimonidine/timolol (dorz/brim/tim) is only available in Latin and South America, and information on its relative efficacy is limited. This study compares the efficacy and tolerability of fixed-combination bimatoprost/timolol (bim/tim) and dorz/brim/tim in Mexican patients with primary open-angle glaucoma or ocular hypertension.

METHODS

In this investigator-masked, crossover study, patients with unmet target intraocular pressure (IOP) on once-daily bim/tim or twice-daily dorz/brim/tim received the opposite medication for 3 months before returning to their pre-baseline medication for 3 months. IOP was evaluated before and after morning instillation at months 2, 3, 5 and 6. Primary endpoints were mean IOP change and Ocular Surface Disease Index© (OSDI) score at each visit. The intent-to-treat population was the a priori analysis population, but due to the number of discontinuations, the per-protocol and intent-to-treat populations were used for the primary efficacy and sensitivity analyses, respectively.

RESULTS

Seventy-eight and 56 patients were included in the intent-to-treat and per-protocol populations, respectively. At month 3, statistically significant IOP reductions from baseline were observed in the bim/tim (P < 0.01) and dorz/brim/tim (P < 0.0001) groups, regardless of assessment time. At month 6, patients returned to bim/tim exhibited no significant IOP increase (regardless of assessment time), but patients returned to dorz/brim/tim exhibited a statistically significant IOP increase (P < 0.001) when assessed before instillation of study treatment. Results were similar in both intent-to-treat and per-protocol analysis populations. In the per-protocol analysis, 70% of patients on bim/tim at month 3 had an IOP <14 mm Hg, which declined to 58% (P = 0.0061) at month 6 (ie, after 3 months of dorz/brim/tim treatment). In patients receiving dorz/brim/tim at month 3, 38% had an IOP <14 mm Hg, which remained comparable after return to bim/tim. OSDI scores and incidence of adverse events were similar in both groups.

CONCLUSIONS

In this first direct comparison of the efficacy of dorz/brim/tim and bim/tim, patients switched from dorz/brim/tim to bim/tim demonstrated improved/lower IOP; when returned to dorz/brim/tim, IOP increased to levels seen at study initiation, suggesting that once-daily bim/tim may have greater IOP-lowering efficacy. Both bim/tim and dorz/brim/tim were well tolerated with minimal ocular surface damage.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01737853 (registered October 9, 2012).

Sigma-1 receptor stimulation protects retinal ganglion cells from ischemia-like insult through the activation of extracellular-signal-regulated kinases 1/2

Sigma-1 receptor (σ-1) activation and mitogen-activated protein kinases (MAPKs) have been shown to protect retinal ganglion cells (RGCs) from cell death. The purpose of this study was to determine if σ-1 receptor stimulation with pentazocine could promote neuroprotection under conditions of an ischemia-like insult (oxygen glucose deprivation (OGD)) through the phosphorylation of extracellular signal regulated kinase (pERK)1/2. Primary RGCs were isolated from P3-P7 Sprague-Dawley rats and purified by sequential immunopanning using Thy1.1 antibodies. RGCs were cultured for 7 days before subjecting the cells to an OGD insult (0.5% oxygen in glucose-free medium) for 6 h. During the OGD, RGCs were treated with pentazocine (σ-1 receptor agonist) with or without BD 1047 (σ-1 receptor antagonist). In other experiments, primary RGCs were treated with pentazocine in the presence or absence of an MEK1/2 inhibitor, PD098059. Cell survival/death was assessed by staining with the calcein-AM/ethidium homodimer reagent. Levels of pERK1/2, total ERK1/2, and beta tubulin expression were determined by immunoblotting and immunofluorescence staining. RGCs subjected to OGD for 6 h induced 50% cell death in primary RGCs (p < 0.001) and inhibited pERK1/2 expression by 65% (p < 0.001). Cell death was attenuated when RGCs were treated with pentazocine under OGD (p < 0.001) and pERK1/2 expression was increased by 1.6 fold (p < 0.05) compared to OGD treated RGCs without pentazocine treatment. The co-treatment of PD098059 (MEK1/2 inhibitor) with pentazocine significantly abolished the protective effects of pentazocine on the RGCs during this OGD insult. Activation of the σ-1 receptor is a neuroprotective target that can protect RGCs from an ischemia-like insult. These results also established a direct relationship between σ-1 receptor stimulation and the neuroprotective effects of the ERK1/2 pathway in purified RGCs subjected to OGD. These findings suggest that activation of the σ-1 receptor may be a therapeutic target for neuroprotection particularly relevant to ocular neurodegenerative diseases that effect RGCs.

Bimatoprost 0.03%/timolol 0.5% preservative-free ophthalmic solution versus bimatoprost 0.03%/timolol 0.5% ophthalmic solution (Ganfort) for glaucoma or ocular hypertension: a 12-week randomised controlled trial

AIM

To compare the efficacy and safety of single-dose bimatoprost 0.03%/timolol 0.5% preservative-free (PF) ophthalmic solution with bimatoprost 0.03%/timolol 0.5% ophthalmic solution in patients with open-angle glaucoma or ocular hypertension.

METHODS

In this multicentre, randomised, parallel-group study, patients were randomised to bimatoprost/timolol PF or bimatoprost/timolol once daily in the morning for 12 weeks. Primary efficacy endpoints, reflecting differing regional regulatory requirements, included change from baseline in worse eye intraocular pressure (IOP) in the per-protocol population at week 12, and the average eye IOP at weeks 2, 6 and 12 in the intent-to-treat population.

RESULTS

561 patients were randomised (278 to bimatoprost/timolol PF; 283 to bimatoprost/timolol); 96.3% completed the study. Both treatment groups showed statistically and clinically significant mean decreases from baseline in worse eye IOP and in average eye IOP at all follow-up time points (p<0.001). Bimatoprost/timolol PF met all pre-established criteria for non-inferiority and equivalence to bimatoprost/timolol. Ocular adverse events were similar between treatment groups, with conjunctival hyperaemia being the most frequent. Most were mild or moderate in severity.

CONCLUSIONS

Bimatoprost/timolol PF demonstrated non-inferiority and equivalence in IOP lowering compared with bimatoprost/timolol, with no significant differences in safety and tolerability.

TRIAL REGISTRATION NUMBER

NCT01177098.

Clinical utility and differential effects of prostaglandin analogs in the management of raised intraocular pressure and ocular hypertension

Prostaglandin analogs (PGA) are powerful topical ocular hypotensive agents available for the treatment of elevated intraocular pressure (IOP). Latanoprost 0.005% and travoprost 0.004% are prodrugs and analogs of prostaglandin F2α. Bimatoprost 0.03% is regarded as a prostamide, and debate continues as to whether it is a prodrug. The free acids of all 3 PGAs reduce IOP by enhancing uveoscleral and trabecular outflow via direct effects on ciliary muscle relaxation and remodeling of extracellular matrix. The vast majority of clinical trials demonstrate IOP-lowering superiority of latanoprost, bimatoprost and travoprost compared with timolol 0.5%, brimonidine 0.2%, or dorzolamide 2% monotherapy. Bimatoprost appears to be more efficacious in IOP-lowering compared with latanoprost, with weighted mean difference in IOP reduction documented in one meta-analysis of 2.59% to 5.60% from 1- to 6-months study duration. PGAs reduce IOP further when used as adjunctive therapy. Fixed combinations of latanoprost, bimatoprost or travoprost formulated with timolol 0.5% and administered once daily are superior to monotherapy of its constituent parts. PGA have near absence of systemic side effects, although do have other commonly encountered ocular adverse effects. The adverse effects of PGA, and also those found more frequently with bimatoprost use include ocular hyperemia, eyelash growth, and peri-ocular pigmentary changes. Iris pigmentary change is unique to PGA treatment. Once daily administration and near absence of systemic side effects enhances tolerance and compliance. PGAs are often prescribed as first-line treatment for ocular hypertension and open-angle glaucoma.

Bimatoprost: a review of its use in open-angle glaucoma and ocular hypertension

Bimatoprost (Lumigan) is a synthetic prostamide that reduces intraocular pressure (IOP) by increasing the outflow of aqueous humour. In patients with open-angle glaucoma or ocular hypertension, long-term treatment (for up to 48 months) with once-daily bimatoprost 0.03% ophthalmic solution was more effective than timolol twice daily in providing a sustained and stable reduction in IOP. Bimatoprost 0.03% ophthalmic solution demonstrated efficacy similar to, or greater than, the prostaglandin analogues latanoprost and travoprost in reducing IOP and achieving target IOP levels. Switching to bimatoprost was as effective in maintaining diurnal IOP control as switching to a fixed combination of latanoprost/timolol (in patients with IOP levels controlled with a nonfixed combination of latanoprost plus timolol), and similarly, or more, effective in lowering IOP and providing overall diurnal IOP control than switching to a combination of dorzolamide/timolol (in patients with IOP inadequately controlled with other antiglaucoma agents including timolol). Treatment with bimatoprost was generally well tolerated, with conjunctival hyperaemia (mostly mild), growth of eyelashes and ocular pruritus being commonly reported. Other adverse events included increases in the pigmentation of the iris, perorbital areas and eyelashes.