Fixed-combination and emerging glaucoma therapies

Comparison of the 24-h efficacy and safety of fixed combination carteolol/latanoprost and timolol/latanoprost in patients with primary open-angle glaucoma and ocular hypertension: a prospective crossover study

PURPOSE

To evaluate the 24-h efficacy and safety of fixed combination carteolol/latanoprost (LCFC) and timolol/latanoprost (LTFC) in patients with primary open-angle glaucoma and ocular hypertension.

STUDY DESIGN

Prospective, randomized, crossover study METHODS: Twenty-two patients pretreated with a prostaglandin analog at baseline were randomly assigned at a 1:1 ratio to either LCFC or LTFC treatment. The patients received the assigned study drug in both eyes daily in the evening (20:00). Each treatment group crossed over after a 2-month treatment period. The 24-h curves of intraocular pressure (IOP), pulse rate, and blood pressure were evaluated. Safety was also assessed.

RESULTS

The changes in mean daytime IOP from baseline at the end of the 2-month treatment period in the LCFC and LTFC groups were  - 0.93 and  - 1.15 mmHg, respectively. The changes in peak IOP in the 2 groups were  - 0.91 and  - 0.68 mmHg, respectively. The nighttime pulse rate in the LCFC group increased; that in the LTFC group was lower at all time points. The changes in pulse rate from baseline at 22:00, 2:00, 4:00, and 6:00 differed statistically between the 2 groups. No differences in changes from baseline in systolic and diastolic blood pressures were found between the groups.

CONCLUSION

The 24-h IOP curve of patients in the LCFC group was similar to that of the LTFC group, but on the basis of the pulse rate findings, the effect of LCFC on the cardiovascular system over 24 h was less than that of LTFC.

A Masked, Randomized, Phase 3 Comparison of Triple Fixed-Combination Bimatoprost/Brimonidine/Timolol versus Fixed-Combination Brimonidine/Timolol for Lowering Intraocular Pressure

OBJECTIVE

To evaluate the efficacy and safety of triple fixed-combination bimatoprost 0.01%/brimonidine 0.15%/timolol 0.5% (TFC) versus dual fixed-combination brimonidine 0.2%/timolol 0.5% (DFC) in primary open-angle glaucoma and ocular hypertension.

METHODS

Patients with intraocular pressure (IOP) ≥23 and ≤34 mmHg were randomized to twice-daily TFC or DFC. The primary variable is the change in worse eye mean IOP from baseline at week 12 (modified intent-to-treat (mITT) population). Secondary endpoints are mean IOP and mean change from baseline at weeks 1, 2, 4, 8, and 12 (mITT population). TFC superiority was demonstrated if the primary variable favored TFC (p ≤ 0.05). Sensitivity analyses were conducted, and safety was assessed at all visits.

RESULTS

TFC (n = 93) provided greater IOP reductions from baseline than DFC (n = 97) at week 12 (treatment difference, 0.85 mmHg; p = 0.028) and all other visits. TFC was also superior to DFC in patients with high baseline IOP (i.e., IOP ≥ 25 mmHg; p ≤ 0.011). Conjunctival hyperemia, ocular irritation, and dry eye were reported more often with TFC (p ≤ 0.016); however, discontinuations for ocular adverse events were similar between treatments.

CONCLUSIONS

TFC demonstrated IOP-lowering benefits that outweigh the risk of predominantly mild ocular side effects, which may be particularly relevant in patients who require greater IOP lowering to prevent/delay disease progression. This trial is registered with ClinicalTrials.gov registry number: NCT01241240.

Glaucoma: Biological Trabecular and Neuroretinal Pathology with Perspectives of Therapy Innovation and Preventive Diagnosis

Glaucoma is a common degenerative disease affecting retinal ganglion cells (RGC) and optic nerve axons, with progressive and chronic course. It is one of the most important reasons of social blindness in industrialized countries. Glaucoma can lead to the development of irreversible visual field loss, if not treated. Diagnosis may be difficult due to lack of symptoms in early stages of disease. In many cases, when patients arrive at clinical evaluation, a severe neuronal damage may have already occurred. In recent years, newer perspective in glaucoma treatment have emerged. The current research is focusing on finding newer drugs and associations or better delivery systems in order to improve the pharmacological treatment and patient compliance. Moreover, the application of various stem cell types with restorative and neuroprotective intent may be found appealing (intravitreal autologous cellular therapy). Advances are made also in terms of parasurgical treatment, characterized by various laser types and techniques. Moreover, recent research has led to the development of central and peripheral retinal rehabilitation (featuring residing cells reactivation and replacement of defective elements), as well as innovations in diagnosis through more specific and refined methods and inexpensive tests.

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).

Glaucoma management: relative value and place in therapy of available drug treatments

Lowering intraocular pressure (IOP) is the only proven therapeutic intervention for glaucomatous optic neuropathy. Despite advances in laser and microsurgical techniques, medical IOP reduction remains the first-line treatment option for the majority of patients with open-angle glaucoma. Prostaglandin analogs are the most efficacious topical agents and carry a remarkable safety profile. Topical beta-blockers, alpha-agonists, and carbonic anhydrase inhibitors are often employed as adjunctive agents for further IOP control. Newer preserved and nonpreserved formulations are available and appear to be less toxic to the ocular surface. Oral carbonic anhydrase inhibitors, miotic agents, and hyperosmotics are infrequently used due to a host of potentially serious adverse events. Medical therapies on the horizon include rho-kinase inhibitors, neuroprotective interventions, and gene therapies.

Effects of prostaglandin analogues on aqueous humor outflow pathways

Elevated intraocular pressure (IOP) is the most prevalent risk factor for glaucoma. All treatments, whether surgical or pharmaceutical, are aimed at lowering IOP. Prostaglandin analogues are a first line therapy for glaucoma due to their ability to reduce IOP, once-daily dosing, efficacy, and minimal side-effect profile. Whereas prostaglandin analogues have been known to alter aqueous humor outflow through the unconventional (uveoscleral) pathway, more recent evidence suggests their action also occurs through the conventional (trabecular) pathway. Understanding how prostaglandin analogues successfully lower IOP is important, as this information may lead to the discovery of new molecular targets for future therapeutic intervention. This review explores the current understanding of prostaglandin analogue biology as it pertains to IOP reduction and improved aqueous humor outflow facility.

Recent advances in pharmacotherapy of glaucoma

Glaucoma is a slow progressive degeneration of the retinal ganglion cells (RGCs) and the optic nerve axons, leading to irreversible blindness if left undiagnosed and untreated. Although increased intraocular pressure is a major risk factor of glaucoma, other factors include increased glutamate levels, alterations in nitric oxide (NO) metabolism, vascular alterations and oxidative damage caused by reactive oxygen species. Glaucoma is the second leading cause of blindness globally, accounting for 12.3% of the total blindness. Glaucoma has been broadly classified as primary or secondary open-angle or angle-closure glaucoma. The primary goal in management of glaucoma is to prevent the risk factor, especially elevated intraocular pressure (IOP), using medications, laser therapy or conventional surgery. The first-line treatment of glaucoma usually begins with the use of a topical selective or nonselective blocker or a prostaglandin analog. Second-line drugs of choice include alpha-agonists and topical carbonic anhydrase inhibitors. Cholinergic agonists are considered third-line treatment options. When a single therapy is not sufficient to lower the IOP, a combination therapy is indicated. To enhance the patient compliance, drug delivery systems like electronic devices, ocular inserts, tansdermal and mechanical drug delivery systems have been developed. Use of viscoelastic agents in ophthalmic formulations, emulsions and soluble ophthalmic drug inserts (SODI) enhance patience compliance and ocular drug delivery in patients in long-term glaucoma therapy. For patients who do not respond to antiglaucoma medications, laser trabeculoplasty and incisional surgery are recommended. Several nutrients and botanicals hold promise for the treatment of glaucoma, but most studies are preliminary, and larger, controlled studies are required. Future directions for the development of a novel therapy glaucoma may target glutamate inhibition, NMDA receptor blockade, exogenously applied neurotrophins, open channel blockers, antioxidants, protease inhibitors and gene therapy.

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.

Visual function, optic nerve structure, and ocular blood flow parameters after 1 year of glaucoma treatment with fixed combinations

PURPOSE

To compare the effects of latanoprost/timolol (LTFC) versus dorzolamide/timolol (DTFC) fixed combinations on intraocular pressure (IOP), visual function, and retrobulbar blood flow in patients with open-angle glaucoma (OAG).

METHODS

This was a prospective, randomized, double masked, parallel study on 30 patients with OAG. All patients received 4 weeks of timolol treatment prior to randomization to LTFC or DTFC treatment. Measurements after randomization were taken at 1, 6, and 12 months, including arterial blood pressure; IOP; color Doppler imaging of the ophthalmic artery (OA), central retinal artery, and short posterior ciliary artery (SPCA); scanning laser polarimetry; Humphrey visual field examination; and adverse events.

RESULTS

IOP decreased by 5.0 mmHg in the DTFC cohort (p<0.000) and 5.44 mmHg in the LTFC cohort (p=0.0001) after 12 months of treatment. No statistically significant differences in visual field or nerve fiber layer thickness were observed between the treatment groups during 12 months of therapy. Mean increase over 1 year of treatment in ocular perfusion and diastolic perfusion pressures were 10.46% and 10.67% in the DTFC group and 7.47% and 5.61% in the LTFC group, respectively. OA resistive index (RI) and SPCA RI were significantly different at the 12 months visit between the two treatment groups (p=0.05 and p=0.000, respectively): DTFC treatment showed decrease in the RI.

CONCLUSIONS

One year of treatment with LTFC or DTFC resulted in similar IOP lowering effects as well as stable visual function and structure. The DTFC group showed lower vascular resistance in retrobulbar vessels compared to the LTFC group.

Designing dendrimers for ocular drug delivery

New series of phosphorus-containing dendrimers, having one quaternary ammonium salt as core and carboxylic acid terminal groups have been synthesized from generation 0 (3 carboxylic acid terminal groups) to generation 2 (12 carboxylic acid terminal groups). These dendrimers react with the neutral form of carteolol (an ocular anti-hypertensive drug used to treat glaucoma) to afford ion pair (saline) species. The solubility in water of these charged dendrimers depends on the generation considered: generation 0 (3 carteolol) is well soluble, whereas generation 1 (6 carteolol) and generation 2 (12 carteolol) are poorly soluble. These dendrimers have been tested in vivo, as vehicle for ocular drug delivery of carteolol to rabbits.

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

Topically administered bimatoprost 0.03%/timolol 0.5% ophthalmic solution (bimatoprost/timolol: Ganfort) comprises the synthetic prostamide bimatoprost (structurally related to prostaglandin F2 alpha) and the beta-adrenergic receptor antagonist timolol. Bimatoprost/timolol (one drop administered in the affected eye[s] once daily in the morning or evening) is an effective and well tolerated fixed combination for lowering intra-ocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension (OHT), including individuals uncontrolled on monotherapy with a beta-adrenergic receptor antagonist or prostaglandin analogue/prostamide.

Ocular pharmacokinetic/pharmacodynamic modeling for multiple anti-glaucoma drugs

We have constructed a new ocular pharmacokinetic pharmacodynamic (PK/PD) model for anti-glaucoma drugs to describe ocular hypotensive effects on intraocular pressure (IOP) after instillation of a combination of an alpha(1)-adrenergic antagonist, bunazosin, and a beta-adrenergic antagonist, timolol, into rabbits. This model was constructed by the combination of two ocular PK/PD models for bunazosin and timolol by including aqueous humor dynamics based on both action mechanisms. We also verified the reliability of this model by confirming the drug concentrations in aqueous humor and ocular hypotensive effects after instillation of the drug combination. The aqueous humor concentrations of timolol and bunazosin were determined by an HPLC, and ocular hypotensive effect-time profiles were measured using a telemetry system, which was able to record automatically detailed effects. The combined model could simulate the aqueous humor concentrations of both drugs and the additive IOP-lowering effect after instillation of the combination using the MULTI (RUNGE) program and PK/PD parameters which were obtained from ocular hypotensive effects after instillation of bunazosin alone or timolol alone. The theoretical concentration curves of both drugs in the aqueous humor and the theoretical ocular hypotensive effect curves almost agreed with both the observed concentrations and ocular hypotensive effects after instillation of the drug combination. These results indicate the reliability and usefulness of PK/PD modeling considering aqueous humor dynamics to predict IOP in multidrug therapy. This is the first study to develop a PK/PD model for multidrug therapy for the eye.

The pharmacology and therapeutic relevance of endocannabinoid derived cyclo-oxygenase (COX)-2 products

The discovery of anandamide and 2-arachidonyl glycerol (2-AG) as naturally occurring mammalian endocannabinoids has had important and wide-reaching therapeutic implications. This, to a large extent, ensues from the complexity of endocannabinoid biology. One facet of endocannabinoid biology now receiving increased attention is the cyclo-oxygenase-2 (COX-2) derived oxidation products. Anandamide and 2-AG are oxidized to a range of PG-ethanolamides and PG-glyceryl esters that closely approaches that of the prostaglandins (PGs) formed from arachidonic acid. The pharmacology of these electrochemically neutral PG-ethanolamides (prostamides) and PG-glyceryl esters appears to be unique. No meaningful interaction with natural or recombinant prostanoid receptors is apparent. Nevertheless, in certain cells and tissues, prostamides and PG-glyceryl esters exert potent effects. The recent discovery of selective antagonists for the putative prostamide receptor has been a major advance in further establishing prostamide pharmacology as an entity distinct from prostanoid receptors. Since discovery of the prototype prostamide antagonist (AGN 204396), rapid progress has been made. The latest prostamide antagonists (AGN 211334-6) are 100 times more potent than the prototype and are, therefore, sufficiently active to be used in living animal studies. These compounds will allow a full evaluation of the role of prostamides in health and disease. To date, the only therapeutic application for prostamides is in glaucoma. The prostamide analog, bimatoprost, being the most effective ocular hypotensive drug currently available. Interestingly, PGE(2)-glyceryl ester and its chemically stable analog PGE(2)-serinolamide also lower intraocular pressure in dogs. Nevertheless, the therapeutic future of PGE(2)-glyceryl ester is more likely to reside in inflammation.

Treatment of glaucoma patients with insufficient intraocular pressure control: a survey of German ophthalmologists in private practice

OBJECTIVE

To assess the degree to which glaucoma treatment guidelines have been incorporated into daily practices and to describe the therapeutic practices chosen for patients with insufficient intraocular pressure (IOP) control.

METHODS

Ophthalmologists in private practice in Germany were surveyed to obtain information about patients who exhibited unsatisfactory progress with IOP-lowering pharmacotherapy. Using a questionnaire, physicians provided data concerning treatment difficulty, target IOP, number and type of medications used, two most recent IOP readings, and optic nerve head and visual field observations.

RESULTS

Of the 853 patients analyzed, primary open-angle glaucoma was the diagnosis for 67.1%, and other diagnoses included ocular hypertension, normal tension glaucoma, and pseudoexfoliation glaucoma. Target IOP levels had been determined for 95.5% of patients, and not achieving the target pressure was identified as a treatment difficulty for 81.0% of patients. Of patients on monotherapy, beta-blockers were prescribed most often (42.3%). Of all patients, 53.3% were treated with two or more agents as either fixed or non-fixed combinations. The non-fixed combination of a prostaglandin and carbonic anhydrase inhibitor was the most frequently prescribed dual therapy (19.2%). Non-fixed prostaglandin plus beta-blocker was used by 18.0% of dual therapy patients, whereas the available fixed combination was used by 10.5%. Non-compliance was identified as a cause of unsatisfactory IOP-lowering in 26.8% of all patients. This study is limited by its descriptive, non-interventional design.

CONCLUSIONS

Treatment alterations are necessary to achieve sufficient IOP control in some patients. If these patients were to take advantage of more aggressive therapies as outlined by treatment guidelines, including newer formulations and fixed combination preparations, both efficacy and compliance may be improved.

Prostamides (prostaglandin-ethanolamides) and their pharmacology

The prostamides are part of a large and continually expanding series of pharmacologically unique neutral lipids. They are COX-2 derived oxidation products of the endocannabinoid/endovanniloid anandamide. Prostamide pharmacology is unique and, as in the case of the endocannabinoids anandamide and 2-arachidonylglycerol, bears little resemblance to that of the corresponding free acids. By virtue of its close relationship to the anti-glaucoma drug bimatoprost, prostamide F(2alpha) has received the greatest research attention. Prostamide F(2alpha) and bimatoprost effects appear independent of prostanoid FP receptor activation, according to a litany of agonist studies. Studies involving freshly isolated and separate feline iridial smooth muscle cells revealed that bimatoprost and FP receptor agonists stimulated different cells, without exception. This suggests the existence of receptors that preferentially recognize prostamide F(2alpha). The recent discovery of prostamide antagonists has provided further support for prostamide receptors as discrete entities. The prototypical prostamide antagonists, AGN 204396 and 7, blocked the effects of prostamide F(2alpha) and bimatoprost but not those of PGF(2alpha) and FP receptor agonists in the feline iris. Second generation more potent prostamide antagonists, such as AGN 211334, should allow the role of prostamides in health and disease to be elucidated. From the therapeutics standpoint, the prostamide F(2alpha) analogue bimatoprost is the most efficacious ocular hypotensive agent currently available for the treatment of glaucoma.