24-Hour control with a latanoprost-timolol fixed combination vs timolol alone

Clinical Trial: Diurnal IOP Fluctuations in Glaucoma Using Latanoprost and Timolol with Self-Tonometry

SIGNIFICANCE

Assessment of treatment efficacy via comparison with a target IOP is fundamental in monitoring patients with open-angle glaucoma and ocular hypertension. This article highlights that diurnal IOP fluctuations obtained using self-tonometry may more accurately reflect IOP responses to therapy.

PURPOSE

This study aimed to investigate fluctuations in diurnal IOP measurements in patients with open-angle glaucoma and ocular hypertension treated with latanoprost 0.005% and timolol 0.25%.

METHODS

In this crossover treatment trial, 14 participants performed self-tonometry with iCare HOME 4 times daily for (1) 1 week using latanoprost, (2) 4 weeks using no medications, and (3) 2 weeks using timolol. Daily peak IOPs, IOP fluctuations, and mean IOPs from different treatments were compared on an individual basis. Treatment efficacy between medications was assessed by comparing mean percentage IOP reductions with latanoprost and timolol across participants. In addition, effects of age, years since commencing latanoprost, sex, and diagnosis were investigated, and peak IOP times were compared with assess impacts on diurnal profiles.

RESULTS

Between individuals, IOP responses ranged from reductions in peak IOPs, IOP fluctuations, and mean IOPs on both medications to no change in any parameter and medication. IOP fluctuations showed greater mean percentage reductions than did peak and mean IOPs (χ2 = 16.51, P = .002). There were significant associations between years since commencing latanoprost and peak and mean IOP responses on timolol (r = 0.69, P = .007), and sex and relative reductions in IOP fluctuations on both medications (P = .03). There were no differences in peak IOP times between treatment conditions.

CONCLUSIONS

Despite variability in IOP responses to latanoprost and timolol, IOP fluctuation with self-tonometry was more consistent in evaluating target IOP, reflecting its importance in ascertaining true IOP response to topical therapies. These findings may impact clinical decision making based on target IOP criteria in patients on topical therapy.

Role of 24-Hour Intraocular Pressure Monitoring in Glaucoma Management

Glaucoma is the leading cause of irreversible blindness worldwide and the prevalence is on the rising trend. Intraocular pressure (IOP) reduction is the mainstay of treatment. The current practice of IOP monitoring is based on spot measurements during clinic visits during office hours. However, there are up to 50% of glaucoma patients who had normal initial IOP, while some treated patients continued to have progressive glaucomatous optic nerve damage even with a low IOP. Recent studies have shown that the IOP of glaucoma patients fluctuated during the day with different patterns, and some of them had peak IOP outside office hours. These findings provided us with new insights on the role of 24-hour IOP monitoring in managing normal tension glaucoma and patients with progressive deterioration despite apparently well-controlled IOP. Nevertheless, results to date are rather inconsistent, and there is no consensus yet. In this review, we briefly highlighted the current modalities of 24-hour IOP monitoring and summarized the characteristic 24-hour IOP pattern and the clinical relevance of IOP parameters in predicting glaucomatous progression in different glaucoma subtypes. We also discussed the therapeutic efficacy of current glaucoma treatment modalities with respect to the mentioned 24-hour IOP profiles, so as to strengthen the role of 24-hour IOP monitoring in identifying and stratifying the risks of progression in glaucoma patients, as well as optimizing treatments according to their IOP profiles.

Diurnal and 24-h Intraocular Pressures in Glaucoma: Monitoring Strategies and Impact on Prognosis and Treatment

The present review casts a critical eye on intraocular pressure (IOP) monitoring and its value in current and future glaucoma care. Crucially, IOP is not fixed, but varies considerably during the 24-h cycle and between one visit and another. Consequently, a single IOP measurement during so-called office hours is insufficient to characterize the real IOP pathology of a patient with glaucoma. To date IOP remains the principal and only modifiable risk factor for the development and progression of glaucoma. Only by evaluating IOP characteristics (mean, peak and fluctuation of IOP) at diagnosis and after IOP-lowering interventions can we appreciate the true efficacy of therapy. Unfortunately, a major limiting factor in glaucoma management is lack of robust IOP data collection. Treatment decisions, advancement of therapy and even surgery are often reached on the basis of limited IOP evidence. Clearly, there is much room to enhance our decision-making and to develop new algorithms for everyday practice. The precise way in which daytime IOP readings can be used as predictors of night-time or 24-h IOP characteristics remains to be determined. In practice it is important to identify those at-risk glaucoma patients for whom a complete 24-h curve is necessary and to distinguish them from those for whom a daytime curve consisting of three IOP measurements (at 10:00, 14:00 and 18:00) would suffice. By employing a staged approach in determining the amount of IOP evidence needed and the rigour required for our monitoring approach for the individual patient, our decisions will be based on more comprehensive data, while at the same time this will optimize use of resources. The patient’s clinical picture should be the main factor that determines which method of IOP monitoring is most appropriate. A diurnal or ideally a 24-h IOP curve will positively impact the management of glaucoma patients who show functional/anatomical progression, despite an apparently acceptable IOP in the clinic. The potential impact of nocturnal IOP elevation remains poorly investigated. The ideal solution in the future is the development of non-invasive methods for obtaining continuous, Goldmann equivalent IOP data on all patients prior to key treatment decisions. Moreover, an important area of future research is to establish the precise relationship between 24-h IOP characteristics and glaucoma progression.

Meta-analysis of Timolol on Diurnal and Nighttime Intraocular Pressure and Blood Pressure

Purpose

To evaluate the nighttime intraocular pressure (IOP) and blood pressure (BP) response to timolol treatment in patients with ocular hypertension or primary open-angle glaucoma.

Methods

This was a meta-analysis of previously published studies that must have been randomized, prospective, crossover or parallel, single or double-masked trials. The treatment period must have been ≥2 weeks with ≥19 patients per treatment arm for a crossover, and ≥50 patients for a parallel designed trial. Studies must have included both baseline and treated 24-hour curves.

Results

For the IOP analysis, we included 8 articles with 340 patients. A reduction from baseline was observed for timolol at each time point and for the 24-hour curve (p≤0.009). When 2 studies, in which timolol was used adjunctively were removed, a similar difference was observed as above at each time point and for the 24-hour curve (p≤0.003). In 2 studies, there were small reductions from baseline for the mean diastolic and systolic BPs at most time points and for the 24-hour curve (3.9 and 4.2 mmHg, respectively) with timolol treatment. The ocular perfusion pressure did not show any difference between baseline and timolol treatment at any time point or for the 24-hour curve (p>0.05).

Conclusions

This meta-analysis suggests that topical timolol therapy provides an ocular hypotensive effect over the 24-hour curve, including the nighttime hours, and while small reductions in the systolic and diastolic pressures occur, the ocular perfusion pressure is not altered over 24 hours.

24-h Efficacy of Glaucoma Treatment Options

Current management of glaucoma entails the medical, laser, or surgical reduction of intraocular pressure (IOP) to a predetermined level of target IOP, which is commensurate with either stability or delayed progression of visual loss. In the published literature, the hypothesis is often made that IOP control implies a single IOP measurement over time. Although the follow-up of glaucoma patients with single IOP measurements is quick and convenient, such measurements often do not adequately reflect the untreated IOP characteristics, or indeed the quality of treated IOP control during the 24-h cycle. Since glaucoma is a 24-h disease and the damaging effect of elevated IOP is continuous, it is logical that we should aim to understand the efficacy of all treatment options throughout the 24-h period. This article first reviews the concept and value of diurnal and 24-h IOP monitoring. It then critically evaluates selected available evidence on the 24-h efficacy of medical, laser and surgical therapy options. During the past decade several controlled trials have significantly enhanced our understanding on the 24-h efficacy of all glaucoma therapy options. Nevertheless, more long-term evidence is needed to better evaluate the 24-h efficacy of glaucoma therapy and the precise impact of IOP characteristics on glaucomatous progression and visual prognosis.

Optimal sampling scheme for estimation of intraocular pressure diurnal curves in glaucoma trials

BACKGROUND AND OBJECTIVE

Effective control of intraocular pressure (IOP) is essential for the successful management of glaucoma. IOP exhibits diurnal variation, yet continuous monitoring is impractical. To date, no clear evidence exists on the number of sampling timepoints required to characterize diurnal IOP and when those measurements should be collected. The objective of this study was to develop an optimized sampling scheme to estimate diurnal IOP and to provide sampling windows for practicality.

METHODS

Baseline IOP values for glaucoma patients were collected from the published literature. A population model-based meta-analysis was performed to develop a model for diurnal IOP that accounts for covariates and inter-study variability. Optimization was performed using the D-optimality criteria to determine optimal sampling times. In addition, various reduced sampling designs were tested to investigate the minimum number of sampling timepoints to precisely estimate diurnal IOP. Also, sampling windows were calculated around the final optimal sampling times to allow flexibility in data collection. The final reduced optimized model was validated by simulating and estimating 500 datasets with reduced optimal sampling times.

RESULTS

The final baseline IOP model included type of glaucoma as a covariate. Bootstrap analysis and visual predictive check plots revealed the adequacy of the model to describe the observed IOP data. Optimization results indicated an increasing trend in bias with decreasing sampling timepoints. A reduced model with four sampling times resulted in acceptable precision (<40 %). Restricting the sampling time between 8 a.m. and 4 p.m. underestimates the fluctuation in diurnal IOP. Sampling windows with ≥95 % efficiency were calculated around the optimized sampling times. Validation results indicated acceptable precision and relative bias for model estimates in the reduced optimized model.

CONCLUSION

A physiologically based mechanistic model was developed to describe the diurnal variation in baseline IOP and inter-study variability was estimated on key diurnal model parameters. Optimization of the final covariate model indicated a reduced sampling time of at least four samples should be collected at 5:45 a.m., 2:15 p.m., 8:00 p.m., and 12:00 a.m. for reliable estimation of diurnal IOP variation.

Design, Analysis, and Reporting of Crossover Trials for Inclusion in a Meta-Analysis

Randomized crossover trials are clinical experiments in which participants are assigned randomly to a sequence of treatments and each participant serves as his/her own control in estimating treatment effect. We need a better understanding of the validity of their results to enable recommendations as to which crossover trials can be included in meta-analysis and for development of reporting guidelines.

Fixed combination of latanoprost and timolol vs the individual components for primary open angle glaucoma and ocular hypertension: a systematic review and meta-analysis

AIM

To assess the effects of the fixed combination of 0.005% latanoprost and 0.5% timolol (FCLT) vs their individual components for primary open angle glaucoma (POAG) and ocular hypertension (OHT).

METHODS

After searched PubMed, EMBASE, the Cochrane Library and SCI, all randomized controlled clinical trials (RCTs) and cross-over studies were included. The control groups were the mono therapy or the concomitant therapy of latanoprost and timolol. The outcomes were visual field defect, optic atrophy, mean intraocular pressure (IOP) and IOP fluctuation. The analysis was carried out in RevMan version 5.1 software.

RESULTS

The post-intervention mean IOP of FCLT was significantly lower compared to timolol [mean difference (MD) -2.92, 95%CI -3.28 to -2.55, P<0.00001] and latanoprost (MD -1.11, 95%CI -1.51 to -0.72, P<0.00001). The post-intervention IOP fluctuation was also significantly lower compared to timolol (MD -0.88, 95%CI -1.23 to -0.53, P<0.00001) and latanoprost (MD -0.63, 95%CI -1.04 to -0.22, P=0.002). The mean IOP was higher in FCLT morning dose group than the one in unfixed combination of 0.005% latanoprost and 0.5% timolol (UFCLT) (MD 1.10, 95%CI 0.81 to 1.39, P<0.00001). Otherwise, there was no difference between FCLT evening dose group and UFCLT (MD 0.34, 95% CI -0.01 to 0.69, P=0.06). There was no statistical difference for the incidence of visual field defect and optic atrophy between FCLT and the monotherapy of components.

CONCLUSION

A better IOP lowering effect has been demonstrated for FCLT compared to the mono therapy of components. The IOP lowering effect was worse for FCLT morning dose and almost same for FCLT evening dose compared to the UFCLT. We need more long-term high quality RCTs to demonstrate the outcomes of visual field defect and optic atrophy.

The Efficacy of a Latanoprost/Timolol Fixed Combination Versus Latanoprost and Timolol Gel-forming Solution Unfixed Combination on Daytime Intraocular Pressure

PURPOSE

To evaluate the effect of a latanoprost/timolol fixed combination (LTFC) versus a latanoprost and timolol gel-forming solution unfixed combination (LTuFC) on daytime intraocular pressure (IOP) levels and fluctuations.

METHODS

This was an 8-week, randomized, parallel-group study. Ninety eyes of 90 patients diagnosed with primary open-angle glaucoma or ocular hypertension that were insufficiently controlled with latanoprost monotherapy were enrolled. Randomized patients received either a single evening dose of LTFC or unfixed combination of latanoprost administered once daily in the evening and timolol gel-forming solution administered once daily in the morning without a washout period. IOP measurements were taken at 8 AM, 11 AM, 2 PM, and 5 PM. The mean IOP, daytime IOP measurements, and fluctuation in IOP were assessed at weeks 4 and 8.

RESULTS

The mean IOP reduction from baseline to each visit was significant in both groups (P<0.01). There was a significant difference in the mean IOP between groups at week 4 (P=0.0021). At week 8, the mean IOP reduction was 3.2 ± 2.1 and 5.7 ± 3.2 mm Hg in LTFC and LTuFC groups, respectively, and the difference was significant (P=0.001). A decrease in the daytime IOP fluctuation was observed in both groups over time, but the decrease in each group was not significant. At week 8, the mean IOP measurements at 8 AM, 11 AM, 2 PM, and 5 PM in LTuFC group were significantly lower than in the LTFC group (P=0.024, 0.0001, 0.0008, and 0.0011, respectively).

CONCLUSIONS

The concomitant use of latanoprost and timolol gel-forming solution leads to a larger additional IOP reduction and lower daytime IOP levels as compared with the fixed combination.

Bimatoprost/timolol fixed combination versus latanoprost in treatment-naïve glaucoma patients at high risk of progression: a pilot study

OBJECTIVE

To compare a fixed combination of 0.03% bimatoprost and 0.5% timolol (BTFC) with latanoprost monotherapy (LM) in treatment-naïve patients with open-angle glaucoma (OAG) and risk factors for glaucomatous progression.

METHODS

Patients were enrolled at 15 sites in Spain and Portugal, and were randomized 1:1 to BTFC or LM. Patients instilled one drop of medication once per day at 8 pm for 12 weeks. The primary outcome was change in intraocular pressure (IOP) at 12 weeks.

RESULTS

Of 81 patients enrolled, 43 were randomized to BTFC and 38 to LM. Mean (SD) change in IOP from baseline to 12 weeks was significantly greater for BTFC than for LM: -13.5 mmHg (4.48) versus -11.4 mmHg (3.19), respectively (P=0.003). Similarly, at 12 weeks, significantly more BTFC patients than LM patients had IOP reductions of ≥40% (74.4% versus 47.4%, P=0.015) or ≥50% (46.5% versus 15.8%, P=0.003). Adverse events were more frequent with BTFC than with LM (33 versus 13 events), but most were mild in severity. The only serious adverse event (colon cancer) was adjudged unrelated to the study medication.

CONCLUSION

BTFC was effective and well tolerated in treatment-naïve patients with OAG at high risk of progression.

Diurnal intraocular pressure with bimatoprost/timolol fixed combination versus latanoprost/timolol fixed combination in healthy subjects

PURPOSE

To evaluate the effects of a bimatoprost/timolol fixed combination (BTFC) and a latanoprost/timolol fixed combination (LTFC) on diurnal intraocular pressure (IOP) and anterior ocular parameters in healthy subjects.

METHODS

We enrolled 58 healthy subjects in this prospective clinical study. Thirty subjects were treated with BTFC and 28 subjects were treated with LTFC. IOP was measured every 2 hours except from 01:00 and 05:00. Axial length, corneal curvature, and anterior chamber depth were obtained using the IOL master at baseline and 24 hours later. Adverse events were assessed by patient interview and by slit lamp examination.

RESULTS

The largest difference in IOP between treated and untreated eyes 8 hours after instillation was 1.67 mmHg in the BTFC group (p < 0.001). The largest difference in IOP between treated and untreated eyes 10 hours after instillation was 1.93 mmHg in the LTFC group (p < 0.001). For anterior ocular parameters such as axial length, corneal curvature, anterior chamber depth at baseline and 24 hours after instillation, there were no significant differences between the baseline and 24-hour values in either the BTFC or LTFC group. The most frequently occurring adverse event was conjunctival hyperemia, which was found in 33.3% (n = 10) of the BTFC group and 25.0% (n = 7) of the LTFC group (p = 0.486).

CONCLUSIONS

BTFC and LTFC provided a significant reduction in IOP from baseline without changing any anterior ocular parameters. Our results provide a reference for monocular trials to assess the effect of eye drops in a clinical condition.

24-hour intraocular pressure and ocular perfusion pressure in glaucoma

This review analyzes the currently available literature on circadian rhythms of intraocular pressure (IOP), blood pressure, and calculated ocular perfusion pressure (OPP) in patients with open-angle glaucoma. Although adequately powered, prospective trials are not available. The existing evidence suggests that high 24-hour IOP and OPP fluctuations can have detrimental effects in eyes with glaucoma. The currently emerging continuous IOP monitoring technologies may soon offer important contributions to the study of IOP rhythms. Once telemetric technologies become validated and widely available for clinical use, they may provide an important tool towards a better understanding of long- and short-term IOP fluctuations during a patient's daily routine. Important issues that need to be investigated further include the identification of appropriate surrogate measures of IOP and OPP fluctuation for patients unable to undergo 24-hour measurements, the determination of formulae that best describe the relationship between systemic blood pressure and IOP with OPP, and the exact clinical relevance of IOP and OPP fluctuation in individual patients. Despite the unanswered questions, a significant body of literature suggests that OPP assessment may be clinically relevant in a significant number of glaucoma patients.

Prostaglandin analogs and timolol-fixed versus unfixed combinations or monotherapy for open-angle glaucoma: a systematic review and meta-analysis

PURPOSE

To estimate the intraocular pressure (IOP)-lowering effect of prostaglandin analogs (PGAs) administered in combination with β-blockers.

METHODS

We searched the Medline and Embase databases for randomized trials comparing topical therapies with PGAs and timolol administered as monotherapy (Mt), or in fixed (FC) or unfixed combinations (UC) to patients with glaucoma or ocular hypertension. The efficacy endpoint was the mean difference (MeD) in the reduction in IOP from baseline; the tolerability endpoint was the incidence of hyperemia.

RESULTS

The 18 eligible trials involved 23 comparisons of FC versus Mt, and 5 of FC versus UC. The FCs were less efficacious than UCs (MeD: 0.69, 95% CI: 0.29 to 1.08). In comparison with timolol Mt, the latanoprost/timolol FC led to a greater IOP reduction (MeD: -2.74, 95% CI: -3.24 to -2.23) than the bimatoprost/timolol FC (MeD: -1.49, 95% CI: -1.86 to -1.12) or the travoprost/timolol FC (MeD: -1.93, 95%CI: -2.98 to -0.88). The FCs led to a lower hyperemia risk than UCs [relative risk (RR): 0.70, 95% CI: 0.43 to 1.14] and PGA Mt (RR: 0.61, 95% CI: 0.53 to 0.70).

CONCLUSIONS

FCs are more efficacious than their individual components, but less efficacious than their respective UCs. FCs lead to a lower hyperemia risk than UCs and their respective PGA Mts.

Long-term medical management of primary open-angle glaucoma and ocular hypertension in the UK: optimizing cost-effectiveness and clinic resources by minimizing therapy switches

PURPOSE

The objective was to assess the long-term economic consequences of the medical management of glaucoma in the UK.

METHODS

The economic evaluation was conducted using the results from a 10-year Markov model based around 3 key triggers for a switch in medical therapy for glaucoma, namely: lack of tolerance (using hyperemia as a proxy); intraocular pressure (IOP) not meeting treatment benchmark; and glaucoma progression. Clinical data from a comprehensive systematic literature review and meta-analysis were used. Direct costs associated with glaucoma treatment are considered (at 2008/9 prices) from the perspective of the UK NHS as payer (outpatient/secondary care setting). Using this model, the economic consequences of 3 prostaglandin-based treatment sequences were compared.

RESULTS

Drug acquisition costs account for around 8% to 13% of the total cost of glaucoma and, if ophthalmologist visits are included, amount to approximately £0.80 to £0.90 per day of medical therapy. The total long-term costs of all prostaglandin strategies are similar because of a shift in resources: increased drug costs are offset by fewer clinic visits to instigate treatment switches, and by avoiding surgery or costs associated with managing low vision. Under the latanoprost-based strategy, patients would have longer intervals between the need to switch therapies, which is largely due to a reduction in hyperemia, seen as a proxy for tolerance. This leads to a delay in glaucoma progression of 12 to 13 months. For every 1000 clinic appointments, 719 patients can be managed for 1 year with a latanoprost-based strategy compared with 586 or 568 with a bimatoprost or travoprost-based strategy.

CONCLUSIONS

Drug acquisition costs are not a key driver of the total cost of glaucoma management and the cost of medical therapy is offset by avoiding the cost of managing low vision. Economic models of glaucoma should include the long-term consequences of treatment as these will affect cost-effectiveness. This analysis supports the hypothesis that the economic and clinical benefits can be optimized by minimizing therapy switches.

Intraocular pressure-lowering combination therapies with prostaglandin analogues

Intraocular pressure (IOP) reduction is currently the only therapeutic approach demonstrated to preserve visual function in patients with glaucoma. The first line of glaucoma treatment consists of topical IOP-lowering medications, usually initiated as monotherapy. A significant proportion of patients require more than one medication to reach a target IOP at which optic nerve damage will not progress. As prostaglandin analogues (PGAs) are the most effective class for reducing IOP, one of the other commonly used classes (β-adrenoceptor antagonist [β-blocker], carbonic anhydrase inhibitor or α(2)-adrenoceptor agonist) is frequently combined with a PGA. In the last decade, the use of fixed combinations containing two medications in a single bottle has steadily increased. Fixed combinations have the potential to simplify the dosing regimen, increase patient adherence, avoid the washout effect of the second drop on the first medication instilled, decrease exposure to preservatives and, sometimes, reduce the cost of treatment. Clinical trials have evaluated PGA-based fixed combinations versus unfixed combinations (individual components administered concomitantly) or versus individual monotherapies; however, any advantage that the fixed combinations may have in terms of IOP-lowering efficacy is still debated. For these reasons, the PGA-based fixed combinations are not approved by regulatory authorities in some countries, such as the US. We review the published studies evaluating the efficacy and tolerability of the IOP-lowering unfixed and fixed combination therapies with PGAs. Regarding unfixed combinations, the review shows that α(2)-adrenergic agonists-PGA and carbonic anhydrase inhibitor-PGA combinations seem to be at least as effective at reducing IOP as the β-blocker-PGA combinations. As for the fixed combinations, the review shows that the three PGA-timolol fixed combinations are more effective than their component medications used separately as monotherapy and are better tolerated than the three respective prostaglandins. The three PGA-timolol fixed combinations are less effective at reducing IOP than the unfixed combinations but are better tolerated. The advantage of the fixed combinations in terms of patient adherence and persistence is supported by a very small number of studies and remains to be more accurately determined. Most studies, but not all, seem to show that PGA-timolol fixed combinations are more effective than other available β-blocker fixed combinations (dorzolamide-timolol fixed combinations) at reducing IOP and are similarly tolerated.

Intraocular pressure-lowering effects of commonly used fixed-combination drugs with timolol: a systematic review and meta-analysis

Background

The first goal of medical therapy in glaucoma is to reduce intraocular pressure (IOP), and the fixed-combination medications are needed to achieve sufficiently low target IOP. The aim of this systematic review and meta-analysis is to evaluate IOP-lowering effect of the commonly used fixed-combination drugs containing 0.5% timolol.

Methods

Pertinent publications were identified through systematic searches. Over 85% of the patients had to be diagnosed with primary open-angle glaucoma (POAG) or ocular hypertension (OHT). Forty-one randomized clinical trials were included in the meta-analysis. The main efficacy measures were the absolute and relative values of mean diurnal IOP reduction, and the highest and lowest IOP reductions on the diurnal IOP curve. The pooled 1- to 3-month IOP-lowering effects after a medicine-free washout period was calculated by performing meta-analysis using the random effects model, and relative treatment effects among different fixed combinations were assessed using a mixed-effects meta-regression model.

Results

The relative reductions for mean diurnal IOP were 34.9% for travoprost/timolol, 34.3% for bimatoprost/timolol, 33.9% for latanoprost/timolol, 32.7% for brinzolamide/timolol, 29.9% for dorzolamide/timolol, and 28.1% for brimonidine/timolol. For the highest IOP decrease, relative reductions ranged from 31.3% for dorzolamide/timolol to 35.5% for travoprost/timolol; for the lowest IOP decrease, those varied from 25.9% for dorzolamide/timolol to 33.1% for bimatoprost/timolol. Both latanoprost/timolol and travoprost/timolol were more effective in lowering mean diurnal IOP than brimonidine/timolol (WMD: 5.9 and 7.0) and dorzolamide/timolol (WMD: 3.8 and 3.3).

Conclusions

All six commonly used fixed-combination drugs containing timolol can effectively lower IOP in patients with POAG and OHT, and both latanoprost/timolol and travoprost/timolol might achieve better IOP-lowering effects among the six fixed-combination agents.

A review of the use of latanoprost for glaucoma since its launch

INTRODUCTION

Prostaglandins are increasingly used as first choice treatment for glaucoma because they are highly effective, lack relevant systemic side effects and require just once-daily administration. Latanoprost is an ester prodrug analog of prostaglandin F2α, which reduces intraocular pressure (IOP) by increasing uveoscleral outflow. Latanoprost 0.005% has received European and US approval as the first-line drug for reducing IOP in patients with open-angle glaucoma or ocular hypertension. Following the recent patent expiry for Xalatan®, a number of latanoprost generics have entered the glaucoma market.

AREAS COVERED

This review, achieved through PubMed and Medline research methods, describes the composition, pharmacokinetics, mode of action, efficacy, side effects and safety profile of latanoprost.

EXPERT OPINION

Latanoprost was the first prostaglandin analog introduced in glaucoma management and it dramatically changed the market of the disease thanks to its efficacy and safety. Conjunctival hyperemia, which is commonly found after latanoprost use, is associated with a minor efficacy and duration of trabeculectomy; yet, from the ophthalmologist's perspective, this side effect seems largely counterbalanced by the high efficacy and safety of this compound. It is always advisable to consider the pro-inflammatory mode of action of latanoprost because this may have negative effects in particular patients (i.e., those with uveitis and cystoid macular edema) for whom caution and close follow-up is necessary.

Efficacy and tolerability of prostaglandin-timolol fixed combinations: a meta-analysis of randomized clinical trials

PURPOSE

To evaluate the intraocular pressure (IOP)-lowering effects and tolerability of the 3 prostaglandin-timolol fixed combinations (PG-timolol FCs).

METHODS

Clinical trials comparing directly the PG-timolol FCs or comparing the PG-timolol FCs to their individual components were thoroughly searched. The main outcome measures were efficacy assessed by IOP (taken at 9 am, noon, 4 pm, and over the mean diurnal curve) change at 3 months (or after 1 to 6 months of treatment if no data were available at month 3) from baseline and tolerability assessed by the incidence of conjunctival hyperemia.

RESULTS

Twenty trials were identified (n = 4684 patients). Intraocular pressure reduction was usually greater with the 3 PG-timolol FCs than the individual PG (mean difference [MD] 0.00 mmHg to 2.59 mmHg; p>0.1 to p<0.001). The incidence of hyperemia was significantly less with latanoprost- and bimatoprost-timolol FCs than with the individual PG (relative risk = 0.66 and 0.61; p = 0.05 and p<0.001). From direct comparisons, IOP reduction was significantly greatest with bimatoprost-timolol FC, at 9 am, 4 pm, and over the mean diurnal curve compared to latanoprost-timolol FC (MD = 0.90 mmHg to 1.48 mmHg; p<0.001) and at all time points compared to travoprost-timolol FC (MD = 0.66 mmHg to 0.90 mmHg; p<0.001). The incidence of hyperemia was not significantly less with latanoprost-timolol FC than with bimatoprost-timolol FC (relative risk = 1.32; p>0.1).

CONCLUSIONS

The 3 PG-timolol FCs provide a greater IOP reduction and lower incidence of hyperemia than the 3 PGs alone. The direct comparisons suggest a greater efficacy of the bimatoprost-timolol FC compared with latanoprost- and travoprost-timolol FCs.

Comparative efficacy and safety of the fixed versus unfixed combination of latanoprost and timolol in Chinese patients with open-angle glaucoma or ocular hypertension

BACKGROUND

A noninferiority trial was conducted to evaluate the efficacy of a single evening dose of fixed-combination latanoprost 50 μg/mL and timolol 0.5 mg/mL (Xalacom®; LTFC), in Chinese patients with primary open-angle glaucoma (POAG) or ocular hypertension (OH) who were insufficiently controlled on β-blocker monotherapy or β-blocker-based dual therapy.

METHODS

This 8-week, randomized, open-label, parallel-group, noninferiority study compared once-daily evening dosing of LTFC with the unfixed combination of latanoprost, one drop in the evening, and timolol, one drop in the morning (LTuFC). The primary efficacy endpoint was the mean change from baseline to week 8 in diurnal intraocular pressure (IOP; mean of 8 AM, 10 AM, 2 PM, 4 PM IOPs). LTFC was considered noninferior to LTuFC if the upper limit of the 95% confidence interval (CI) of the difference was < 1.5 mmHg (analysis of covariance).

RESULTS

Baseline characteristics were similar for LTFC (N = 125; POAG, 70%; mean IOP, 25.8 mmHg) and LTuFC (N = 125; POAG, 69%; mean IOP, 26.0 mmHg). Mean diurnal IOP changes from baseline to week 8 were -8.6 mmHg with LTFC and -8.9 mmHg with LTuFC (between-treatment difference: 0.3 mmHg; 95%-CI, -0.3 to 1.0). Both treatments were well tolerated.

CONCLUSIONS

A single evening dose of LTFC was at least as effective as the unfixed combination of latanoprost in the PM and timolol in the AM in reducing IOP in Chinese subjects with POAG or OH whose IOP was insufficiently reduced with β-blocker monotherapy or β-blocker-based dual therapy. LTFC is an effective and well tolerated once-daily treatment for POAG and OH.

Managing refractory glaucoma with a fixed combination of bimatoprost (0.03%) and timolol (0.5%)

Glaucoma is a chronic progressive optic neuropathy characterized by progressive loss of retinal ganglion cells, which manifests clinically with loss of optic disc neuroretinal rim tissue, defects in the retinal nerve fiber layer, and deficits on functional visual field testing. The goal of glaucoma treatment is to reduce the intraocular pressure to a level that prevents or minimizes the progressive loss of vision. The current standard of management for the newly diagnosed primary open angle glaucoma (PAOG) patient is to start topical medication. Available topical medications include: beta-adrenergic antagonists, alpha-adrenergic agonists, carbonic anhydraze inhibitors, prostaglandin analogues and miotics. In some patients, IOP is not adequately controlled by monotherapy. In those refractory patients, where more efficacy is required, shifting to another medication or adding a second medication is indicated. The complimentary action between two drugs serves as the basis for combination medications. One avenue of delivering a second medication is through a fixed combination medication that has the advantage of providing two medicines within one drop. Bimatoprost/timolol represents a new fixed combination which is clinically and statistically more effective than either of its active constituents for patients with refractory glaucoma. As regard the safety of the combination, there were no signs or symptoms of intolerance and the incidence of conjunctival hyperemia was clinically and statistically significantly less than each of the two components separately. Bimatoprost/timolol fixed combination offers cost and time savings, which may enhance compliance; also reducing the amount of preservative applied to the eye, will improve tolerability and may also favorably improve eventual surgical outcomes in patients who might require filtering procedures.

A 12-week, randomized, double-masked study of fixed combination latanoprost/timolol versus latanoprost or timolol monotherapy

PURPOSE

To evaluate the efficacy and safety of fixed combination latanoprost/timolol versus latanoprost or timolol monotherapy.

METHODS

This 12-week, randomized, double-masked study was designed to overcome potential shortcomings of previous trials. We enrolled 788 subjects with open-angle glaucoma or ocular hypertension treated with a beta-blocker for > or = 4 weeks before screening. After washout, 500 subjects with a baseline mean intraocular pressure (IOP) > or = 26 and < 37 mmHg were randomized to fixed combination latanoprost-timolol in the evening (n = 170), latanoprost monotherapy in the evening (n = 165), or timolol monotherapy in the morning (n = 165). At weeks 2, 6, and 12, each subject's IOP level was measured in triplicate at 8 AM (predose), 10 AM, and 4 PM in each eye. Adverse events were monitored throughout. The statistical superiority of the fixed combination for the 18 pairwise comparisons with the 2 monotherapies was evaluated (analysis of variance). RESULTS. The statistical superiority of the fixed combination was demonstrated at 7/9 time points versus latanoprost and 9/9 time points versus timolol. Mean diurnal IOP levels were similar at baseline but significantly lower with the fixed combination than with either monotherapy at weeks 6 and 12 (each p < 0.05). Patients treated with the fixed combination were significantly more likely than those treated with either monotherapy to reach prespecified percent IOP reductions at the upper thresholds and to achieve very low target diurnal IOP levels. All therapies were well tolerated. CONCLUSIONS. Fixed combination latanoprost/timolol safely reduces IOP levels in patients with glaucoma or ocular hypertension, though only slightly more than does latanoprost monotherapy.

Control of intraocular pressure and fluctuation with fixed-combination brimonidine-timolol versus brimonidine or timolol monotherapy

PURPOSE

To evaluate control of intraocular pressure (IOP) and IOP fluctuation in patients with ocular hypertension or glaucoma treated with fixed-combination brimonidine-timolol compared with brimonidine or timolol monotherapy.

DESIGN

Post hoc analysis of data from 2 identical, 12-month, randomized, double-masked, multicenter trials.

METHODS

Patients were treated bilaterally with fixed brimonidine-timolol twice a day (n = 385), brimonidine tartrate 0.2% 3 times a day (n = 382), or timolol 0.5% twice a day (n = 392). Diurnal IOP was measured at follow-up visits at weeks 2 and 6 and months 3, 6, 9, and 12. IOP fluctuation was defined as the standard deviation of IOP measurements.

RESULTS

The percentage of patients with mean diurnal IOP <18 mm Hg and short-term (daily) IOP fluctuation ≤2 mm Hg was statistically significantly higher in the brimonidine-timolol group than in the brimonidine or timolol group at each follow-up visit (at month 12, brimonidine-timolol 43.0%; brimonidine 18.9%, timolol 33.5%, P ≤ .017). At each hour (8 AM, 10 AM, 3 PM, and 5 PM), the percentage of patients with mean IOP <18 mm Hg and long-term (intervisit) IOP fluctuation ≤2 mm Hg was statistically significantly higher with brimonidine-timolol than with brimonidine or timolol alone (at 8 AM, brimonidine-timolol 41.0%, brimonidine 11.3%, timolol 23.7%, P < .001).

CONCLUSIONS

Patients treated with fixed-combination brimonidine-timolol were more likely than patients treated with either brimonidine or timolol alone to achieve a combination of low mean IOP and low short-term (daily) or long-term (intervisit) IOP fluctuation.

Mixed treatment comparison and meta-regression of the efficacy and safety of prostaglandin analogues and comparators for primary open-angle glaucoma and ocular hypertension

OBJECTIVES

Primary open-angle glaucoma (POAG) is a chronic condition characterised by optic neuropathy and vision loss. Elevated intraocular pressure (IOP) can damage the optic nerve and is a risk factor for glaucoma, thus treatment usually comprises topical hypotensives. This analysis aims to address methodological issues associated with the synthesis of glaucoma clinical trial data, given variations in study methodology and IOP measurement.

METHODS

Meta-regression was used to estimate how IOP varies over time for patients receiving treatment. Relative treatment effects were assessed using a random-effects mixed treatment comparison (MTC) in order to preserve randomisation and avoid selection bias. To produce clinically meaningful outputs, these analyses were combined to obtain the mean on-treatment IOP and the proportion of patients achieving different IOP targets at different time points. A further MTC estimated the probability of hyperaemia events.

RESULTS

The analysis showed that after 3 months' treatment, between 58 and 83% of patients will have a > or =20% reduction in IOP and 70-93% of patients will have an absolute IOP <20 mmHg. Latanoprost and bimatoprost were found to produce significantly lower on-treatment IOP compared with timolol (p < 0.05); the difference between latanoprost and bimatoprost was not significant. Travoprost produced a lower mean IOP compared with timolol (not significant). Latanoprost-timolol was found to produce significantly lower IOP than latanoprost alone or beta-blockers. The probability of hyperaemia-type events varied between treatments from 14.8 to 63.03%. Latanoprost had significantly lower odds of hyperaemia than travoprost, bimatoprost, travoprost-timolol, or bimatoprost-timolol.

CONCLUSION

This analysis suggests that latanoprost and bimatoprost produce a statistically significant reduction in IOP compared with timolol, but are associated with a higher risk of hyperaemia. Out of all the prostaglandins, latanoprost may achieve a good balance between tolerability and IOP efficacy. As with all forms of meta-analysis, the results are based on the assumption that the studies and intervention groupings are sufficiently similar to be compared.

24-hour intraocular pressure and blood pressure levels with latanoprost/timolol fixed combination versus timolol

PURPOSE

To evaluate 24-hr intraocular pressure (IOP) and blood pressure (BP) with timolol or latanoprost/timolol fixed combination (LTFC).

METHODS

Patients with primary open-angle glaucoma or ocular hypertension with normal blood pressure were randomized to LTFC, dosed each evening, or timolol dosed twice daily in a cross-over design for 8 weeks and the opposite medicine for 8 weeks. IOP was measured at 02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 hours in the sitting position with Goldmann applanation tonometry and BP monitoring every 30 min while awake and every hour while asleep at the end of each 8-week treatment period.

RESULTS

Twenty-nine patients had a 24-hr baseline IOP of 26.3 +/- 2.5 mmHg, systolic BP (SBP) of 121.4 +/- 12.4 mmHg, diastolic BP (DBP) 72.9 +/- 7.1 mmHg, and ocular perfusion pressure (OPP) of 33.9 +/- 5.7 mmHg. No statistical differences were found between untreated and treated 24-hr SBP, DBP, mean BP (MBP), heart rate, or nocturnal BP dipping status with either medication. LTFC lowered IOP more at each timepoint compared to timolol (difference between treatments 2.7 mmHg, p = 0.0002).

CONCLUSIONS

Neither timolol or evening-dosed LTFC reduced SBP, DBP, MBP, OPP, or increased nocturnal dipping. LTFC was more effective than timolol in decreasing IOP.

Effects of medications and surgery on intraocular pressure fluctuation

Intraocular pressure (IOP) varies dynamically throughout the circadian cycle. IOP elevations during the nocturnal period may be particularly important in the pathogenesis of glaucoma, although sleeping IOP cannot be measured at this time. Additionally, IOP fluctuations may be an independent risk factor for glaucoma. However, not all glaucoma therapies are equally effective at lowering IOP throughout the 24-hour period. The prostaglandin analogs have excellent IOP control throughout the 24-hour period, although less at night than during the day. In contrast, some other classes of medications, such as the beta-blockers, have little or no IOP-lowering effect at night. The prostaglandin analogs also have excellent persistency of IOP lowering, lasting at least as long as the 24-hour dosing period, and likely much longer. Glaucoma filtering surgery appears to have even better 24-hour IOP reduction and smaller fluctuations than maximal medical therapy including prostaglandin analogs.

A comparison of long-term intraocular pressure fluctuation in patients treated with bimatoprost or latanoprost

PURPOSE

To evaluate long-term intraocular pressure (IOP) fluctuation in patients with glaucoma or ocular hypertension treated with bimatoprost or latanoprost.

DESIGN

Post hoc analysis of prospectively collected data from a previously reported multicenter, investigator-masked, randomized clinical trial of bimatoprost and latanoprost.

METHODS

Patients were treated bilaterally with bimatoprost (n = 133) or latanoprost (n = 136) for six months. IOP measurements were taken at 8 am, 12 pm, and 4 pm at baseline, week 1, and months 1, 3, and 6. Long-term IOP fluctuation during treatment was determined as the standard deviation (SD) of all 12 follow-up measurements.

RESULTS

There was no significant between-group difference in short-term daily IOP fluctuation at baseline. Long-term IOP fluctuation over six months of treatment [mean SD (range SD)] was 1.9 (0.5 to 6.3) mm Hg with latanoprost vs 1.7 (0.5 to 3.9) mm Hg with bimatoprost (P = .050). Latanoprost-treated eyes were more likely than bimatoprost-treated eyes to have long-term IOP fluctuation of > or =3 mm Hg (7.8% vs 2.5% of eyes; P = .009).

CONCLUSIONS

Bimatoprost-treated eyes demonstrated less long-term fluctuation in IOP compared with latanoprost-treated eyes in this six-month study. Additional studies are needed to confirm these findings and to determine their impact on glaucomatous progression.

24-hour control of intraocular pressure with 2% dorzolamide/0.5% timolol fixed-combination ophthalmic solution in open-angle glaucoma

OBJECTIVE

To evaluate the 24-hour efficacy and tolerability of 2% dorzolamide/0.5% timolol fixed combination (DTFC) solution in open-angle glaucoma and ocular hypertension.

RESEARCH DESIGN AND METHODS

Randomized, parallel, double-masked, multicenter study. Patients with insufficiently controlled intraocular pressure (IOP > or = 22 mmHg) were randomized to DTFC (N = 117) or timolol (N = 115). IOP was measured at baseline, 6 weeks, and 8 weeks, with measurements taken at 6 p.m., 8 p.m., 10 p.m., 2 a.m., 6 a.m., 8 a.m., 10 a.m., and 2 p.m. ClinicalTrials. gov identifier: NCT00108017 MAIN OUTCOME MEASURES: Statistically significant change in IOP from untreated baseline for DTFC at all hours at week 8. Secondary outcome measures included: IOP-lowering at week 6 at all individual time points, change from baseline to 8 weeks in mean daytime IOP (average of 8 a.m., 10 a.m., 2 p.m., 6 p.m., and 8 p.m. IOPs) and night-time IOP (10 p.m., 2 a.m., 6 a.m.), and comparison of DTFC with timolol after 8 weeks.

RESULTS

Patients receiving DTFC had a statistically significant and clinically relevant reduction in IOP at week 8 compared with baseline at all eight time points (p < 0.001). Significant IOP reductions were also seen at all time points at week 6 (p < 0.001). DTFC significantly lowered mean daytime IOP and night-time IOP ( p < 0.001 for both). Timolol alone also significantly reduced IOP from baseline at 8 weeks for all diurnal time points, and mean daytime and night-time IOP ( p < 0.001 for all). Compared with timolol alone, there were significantly greater reductions with DTFC at 10 a. m. (p = 0.003) and 2 p. m. (p = 0.016), and for mean daytime IOP (p = 0.025) at 8 weeks. Significant between-treatment differences were not observed at other time points. Both treatments were well-tolerated, with no differences observed in the safety profiles between the treatment groups.

CONCLUSIONS

Both DTFC and timolol provided significant IOP reduction over the entire 24-hour measurement period. Although this study was not designed or powered to compare DTFC and timolol, DTFC exhibited greater IOP-lowering than timolol during the daytime, but not at night.

Dorzolamide/timolol fixed combination versus latanoprost/timolol fixed combination in patients with primary open-angle glaucoma or ocular hypertension

PURPOSE

The efficacy of dorzolamide/timolol fixed combination (DTFC) versus latanoprost/timolol fixed combination (LTFC) in open-angle glaucoma or ocular hypertensive patients.

METHODS

Patients were randomized to DTFC or LTFC for 6 weeks and switched to opposite treatment for Period 2.

RESULTS

Thirty-two completed patients had a mean diurnal IOP of 19.5+/-3.2 mmHg for DTFC and 18.9+/-3.4 mmHg for LTFC (p=0.12), with no significant difference found between DTFC and LTFC at any timepoint following a Bonferroni correction (p>or=0.01).

CONCLUSIONS

Patients treated with DTFC and LTFC have a statistically similar ocular hypotensive effect.

Meta-analysis of 24-hour intraocular pressure studies evaluating the efficacy of glaucoma medicines

PURPOSE

To evaluate efficacy and safety data of currently available ocular hypotensive medicines derived from 24-hour studies, of similar design, in patients with primary open-angle glaucoma (POAG), exfoliative glaucoma, or ocular hypertension (OH).

DESIGN

Meta-analysis of published articles evaluating patients with POAG, exfoliative glaucoma, or OH.

METHODS

We included articles that were randomized, prospective, single- or double-masked, comparative studies of ocular hypotensive therapies over 24 hours. Each article selected contained an untreated baseline, >or=4-week treatment period, >/=20 patients per treatment arm, and >or=6 time points not spaced >5 hours apart and used Goldmann applanation or Tonopen tonometry (supine measurements) to measure intraocular pressure (IOP).

MAIN OUTCOME MEASURE

Twenty-four-hour IOP efficacy.

RESULTS

This analysis included 864 separate 24-hour treatment curves from 386 patients in 28 treatment arms from 11 studies. A statistical difference in the mean diurnal pressure decrease existed between monotherapy treatments for POAG/OH patients, with bimatoprost (29%) and travoprost (27%) showing the greatest 24-hour reduction (P = 0.026). Timolol 0.5% was less effective than latanoprost (24% vs. 19% reduction) but decreased the pressure at each night time point (P = 0.0003). Dorzolamide showed a 19% 24-hour pressure reduction and brimonidine 0.2% a 14% one. In exfoliative glaucoma patients, latanoprost and travoprost showed higher baseline and treatment pressures, although the pressure reductions (29% and 31%, respectively) were greater generally than observed with POAG/OH. An evening-dosed latanoprost/timolol fixed combination reduced the pressure 33%, and the dorzolamide/timolol fixed combination (DTFC), 26%. However, the power to detect a difference for this specific comparison was probably low, due to the limited number of patients (n = 20) in the DTFC group. A statistical difference between evening-dosed (24%) and morning-dosed (18%) latanoprost (P<0.0001) was noted, but not between evening (27%) and morning (26%) travoprost (P = 0.074). The mean reduction of night time points was statistically lower than day time points for latanoprost (P = 0.031), timolol (P = 0.032), and brimonidine (P = 0.050), but not for dorzolamide. Dorzolamide (P = 0.60), travoprost (P = 0.064), and bimatoprost (P = 0.057) did not demonstrate nighttime pressures lower than daytime ones. The mean reduction of night time points was statistically lower than that of day time points for latanoprost (P = 0.031), timolol (P = 0.032), and brimonidine (P = 0.050), but not for dorzolamide (P = 0.60), bimatoprost (P = 0.057), travoprost (P = 0.064).

CONCLUSIONS

Similar relative efficacies generally exist in various classes of ocular hypotensive agents during night and day hours.