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

Dorzolamide/Timolol Fixed Combination: Learning from the Past and Looking Toward the Future

The key clinical attributes of preserved dorzolamide/timolol fixed combination (DTFC) and the emerging potential of preservative-free (PF) DTFC are reviewed with published evidence and clinical experience. The indications and role of DTFC in current glaucoma management are critically discussed. Preserved DTFC became the first intraocular pressure (IOP)-lowering fixed combination (FC) approved by the US Food and Drug Administration (FDA) and remains one of most commonly used medications worldwide. The pharmacological properties of DTFC reflect those of its two time-tested constituents, i.e., the carbonic anhydrase inhibitor dorzolamide and the non-selective beta-blocker timolol. In regulatory studies DTFC lowers IOP on average by 9 mmHg (32.7%) at peak and by 7.7 mmHg (27%) at trough. In trials DTFC shows equivalence to unfixed concomitant therapy, but in real-life practice it may prove superior owing to enhanced convenience, elimination of the washout effect from the second drop, improved tolerability, and better adherence. PF DTFC became the first PF FC approved, first in unit-dose pipettes, and more recently in a multidose format. Cumulative evidence has confirmed that PF DTFC is at least equivalent in efficacy to preserved DTFC and provides a tangible clinical benefit to patients with glaucoma suffering from ocular surface disease by improving tolerability and adherence. Finally, we identify areas that warrant further investigation with preserved and PF DTFC

Preservative-Free Prostaglandin Analogs and Prostaglandin/Timolol Fixed Combinations in the Treatment of Glaucoma: Efficacy, Safety and Potential Advantages

Glaucoma therapy-related ocular surface disease (OSD) is a serious pathology with a broad spectrum of insidious clinical presentations and complex pathogenesis that undermines long-term glaucoma care. Preservatives, especially benzalkonium chloride (BAK), contained in topical intraocular pressure-lowering medications frequently cause or aggravate OSD in glaucoma. Management of these patients is challenging, and to date often empirical due to the scarcity of controlled long-term clinical trials. Most of the available data are extracted from case series and retrospective analysis. Preservative-free prostaglandins and prostaglandin/timolol fixed combinations are novel options developed to remove the harmful impact of preservatives, especially BAK, upon ocular tissues. Based on what is currently known on the value of preservative-free antiglaucoma therapies it is tempting to speculate how these new therapies may affect the future medical management of all glaucoma patients. This article provides a comprehensive and critical review of the current literature on preservative-free prostaglandins and preservative-free prostaglandin/timolol fixed combinations.

Nonclinical Development of Combination Drugs

We define "combination drugs" as "fixed-dose combinations" (FDCs), that is, two or more drugs (marketed or not) combined in a single pill or two or more separate drugs packaged together. FDCs have been available commercially for many years but only relatively recently have nonclinical development guidelines been released by a number of regulatory authorities and the World Health Organization; as yet there are no ICH guidelines specific to combination drugs. In general however, the ICH guidelines for monotherapy development provide a framework for FDC development. Depending on the type of drug combination (marketed drug/marketed drug; marketed drug/NME and NME/NME) the scope and complexity of toxicity studies will vary greatly. In all cases however, a key issue is the potential for pharmacokinetic and/or toxicologic interaction between the components. For a marketed drug/marketed drug combination a detailed review of the nonclinical data available may suffice, particularly when the components have a history of coadministration at about the same dose and ratio as that of the proposed combination. For a marketed drug/NME combination, in addition to a review of the data for the marketed drug, a full ICH program of studies will be required for the NME, and a study of up to 90-day duration (in one species) for the combination. With an NME/NME combination each component will require a full ICH battery of studies and a combination study in one species. In all cases additional studies may be needed to address data gaps. Given the many novel and complex issues which arise when developing FDCs we recommend that, whenever possible, the nonclinical study strategy is discussed with the regulatory authorities.

Randomized, Controlled, Phase 3 Trials of Carteolol/Latanoprost Fixed Combination in Primary Open-Angle Glaucoma or Ocular Hypertension

PURPOSE

To assess the intraocular pressure (IOP)-lowering effects and safety of a carteolol/latanoprost fixed combination drug (OPC-1085EL) vs latanoprost (Study 1) and carteolol (Study 2) in patients with primary open-angle glaucoma (POAG) or ocular hypertension (OH).

DESIGN

Multicenter, randomized, evaluator-masked (Study 1)/double-masked (Study 2), parallel-group studies.

METHODS

Setting: Twenty-eight clinical sites (Study 1) and 19 clinical sites (Study 2) in Japan.

STUDY POPULATION

Outpatients with bilateral POAG or OH whose predose IOP was 18 to <35 mm Hg in the study eye after 4 weeks' treatment with latanoprost (Study 1) or carteolol (Study 2) (defined as baseline).

INTERVENTION

In Study 1, 237 patients applied OPC-1085EL (n = 118) or latanoprost (n = 119) for 8 weeks. In Study 2, 193 patients applied OPC-1085EL (n = 78), carteolol (n = 78), or carteolol/latanoprost concomitant therapy (n = 37) for 8 weeks.

MAIN OUTCOME MEASURE

Adjusted mean IOP reduction at predose from baseline to week 8.

RESULTS

In Study 1, the adjusted mean IOP reductions (95% confidence interval [CI]) were 2.9 (2.5-3.3) mm Hg and 1.6 (1.2-2.0) mm Hg in the OPC-1085EL and latanoprost groups, respectively (P < .0001). In Study 2, the adjusted mean IOP reductions (95% CI) were 3.5 (3.1-3.9) mm Hg and 1.6 (1.2-2.0) mm Hg in the OPC-1085EL and carteolol groups, respectively (P < .0001). All adverse drug reactions of OPC-1085EL observed in both studies were mild in severity and only 1 patient in each study discontinued because of an adverse drug reaction.

CONCLUSIONS

OPC-1085EL is superior to latanoprost or carteolol alone in terms of lowering IOP, and was well tolerated.

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 brinzolamide/timolol in Latin American patients with open-angle glaucoma or ocular hypertension previously on brimonidine/timolol fixed combination

INTRODUCTION

Fixed-combination glaucoma medications are commonly used to achieve target intraocular pressure (IOP) reduction in patients uncontrolled with monotherapy; however, ocular discomfort associated with eye drops can decrease adherence. This study assessed the efficacy and tolerability of twice-daily fixed-combination brinzolamide 1%/timolol 0.5% (BRINZ/TIM-FC) in Latin American patients transitioned from fixed-combination brimonidine 0.2%/timolol 0.5% (BRIM/TIM-FC) because of insufficient IOP control or treatment intolerance.

METHODS

This 8-week, open-label, prospective study was conducted at six sites in Argentina, Chile, and Mexico. Enrolled patients were aged ≥18 years with open-angle glaucoma (including primary, exfoliative, or pigment-dispersion glaucoma) or ocular hypertension with IOP of 19-35 mmHg in ≥1 eye at baseline (on BRIM/TIM-FC). Patients self-administered BRINZ/TIM-FC to both eyes at 8 a.m. and 8 p.m. daily for 8 weeks. The primary and secondary efficacy endpoints were mean IOP change from baseline at week 8 and percentage of patients achieving target IOP (≤18 mmHg) at week 8, respectively. Exploratory endpoints included patient and investigator preference for treatment at week 8. Adverse events (AEs) were assessed as the safety endpoint.

RESULTS

Fifty patients (mean ± SD age, 66.7 ± 11.5 years) received BRINZ/TIM-FC, and 49 were included in the intent-to-treat population. Mean ± SD IOP was significantly reduced from baseline after 8 weeks of treatment with BRINZ/TIM-FC (-3.6 ± 3.0 mmHg; P < 0.0001, Wilcoxon signed-rank test; 17.1% reduction). Overall, 55.3% of patients achieved IOP ≤18 mmHg at week 8. Significantly more patients (89.4%) and investigators (95.7%) preferred BRINZ/TIM-FC to BRIM/TIM-FC (both P < 0.0001, exact binomial test). Of the 13 AEs observed, 8 were related to BRINZ/TIM-FC; the most common treatment-related AEs were eye irritation (n = 4) and abnormal sensation in the eye (n = 2).

CONCLUSION

BRINZ/TIM-FC provides an effective and well-tolerated treatment option for patients transitioned from BRIM/TIM-FC.

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

Glaucoma is one of the leading causes of blindness and is characterized by optic nerve damage that results in visual field loss. Elevated intraocular pressure (IOP) has been associated with glaucoma progression; thus, IOP-lowering medications are the standard of care for glaucoma. Guidelines suggest monotherapy with IOP-lowering agents such as β-blockers (eg, timolol), prostaglandin analogs, carbonic anhydrase inhibitors (eg, brinzolamide), and α2-receptor agonists (eg, brimonidine). However, monotherapy may provide insufficient IOP reduction in some patients, thereby necessitating the use of multiple IOP-lowering medications. Multidrug regimens may be complex, may increase the risk of preservative-related ocular symptoms, and may potentially reduce overall drug exposure as a consequence of drug washout during closely timed sequential administrations; these difficulties may reduce overall drug efficacy and decrease patient persistence and adherence with multidrug treatment regimens. Fixed-combination medications that provide two IOP-lowering therapies within a single solution are available and may overcome some of these challenges. However, all currently available fixed combinations combine timolol with another IOP-lowering agent, indicating that additional fixed-combination alternatives would be beneficial. To meet this demand, a novel fixed combination of brinzolamide 1% and brimonidine 0.2% (BBFC) has recently been developed. In two randomized, double-masked, multinational clinical trials, BBFC had greater IOP-lowering efficacy than brinzolamide or brimonidine monotherapy after 3 months of treatment in patients with open-angle glaucoma or ocular hypertension. In both studies, the overall safety profile of BBFC was consistent with that of brinzolamide and brimonidine. Comparative studies with BBFC versus other IOP-lowering monotherapy and fixed-combination medications are not available, but the IOP reductions observed with BBFC are similar to or greater than those reported in the literature for other glaucoma treatments; thus, BBFC provides an additional fixed-combination therapeutic option for patients who require further efficacious IOP reduction and improved convenience and tolerability versus concomitant administration of two separate medications.

How ocular surface disease impacts the glaucoma treatment outcome

The treatment goals for glaucoma are lowering the intraocular pressure and preservation of vision. Topical hypotensive drops are the standard form of therapy which is often associated with some symptoms of toxicity, ocular inflammation, allergy, or ocular surface disease (OSD). OSD is a common comorbidity in glaucoma patients, and its prevalence with glaucoma increases with age. Use of topical treatment could additionally increase symptoms of OSD mostly due to preservatives added to multidose medication bottles used to reduce the risk of microbial contamination. This toxicity has been particularly associated with BAK, the most commonly used preservative which damages conjunctival and corneal epithelial cells and significantly aggravates OSD symptoms. OSD adversely affects patients' quality of life causing discomfort and problems with vision which in turn may result in noncompliance, lack of adherence, and eventually visual impairment. In the management of glaucoma patients OSD symptoms should not be overlooked. If they are present, topical glaucoma treatment should be adapted by decreasing the amount of drops instilled daily, using BAK-free or preservative-free medication and lubricants if necessary. Awareness of the presence and importance of OSD will in turn improve patients' adherence and compliance and thus ultimately the preservation of long-term vision.