Daytime diurnal curve comparison between the fixed combinations of latanoprost 0.005%/timolol maleate 0.5% and dorzolamide 2%/timolol maleate 0.5%

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

The efficacy of the fixed combination of latanoprost and timolol versus other fixed combinations for primary open-angle glaucoma and ocular hypertension: A systematic review and meta-analysis

BACKGROUND

Fixed-combination (FC) therapy is used in primary open-angle glaucoma (POAG) and ocular hypertension (OHT) patients who require more than one medication to reach their target intraocular pressure (IOP). Currently, there are several FC therapies available for the treatment of glaucoma. The FC of latanoprost/timolol (LTFC) is a commonly used FC. Here, we conducted systematic review to compare the IOP-lowering effects of LTFC with other FCs for patients with POAG and OHT.

MATERIALS AND METHODS

We searched PubMed, EMBASE, the Cochrane Library, and Web of Science for randomized-controlled clinical trials and cross-over studies. The outcomes were mean IOP and IOP fluctuation after one month of treatment. Meta-analysis was carried out using RevMan (version 5.1) software. After conducting meta-analyses, we rated the quality of each meta-analysis as high, moderate, low, or very low using the "GRADE" system.

RESULTS

We included 16 trials in this meta-analysis. Moderate-quality meta-analysis showed that LTFC had a comparable mean IOP to that of a fixed combination of travoprost and timolol (TTFC) [mean difference (MD): 0.07 mmHg] and a fixed combination of dorzolamide and timolol (DTFC) [MD: -0.31 mmHg], and it also had a comparable IOP-fluctuation effect compared to that of TTFC [MD: 0.13 mm Hg] and DTFC [MD: 0.25 mmHg]. Compared to the fixed combination of bimatoprost and timolol (BiTFC), moderate-quality evidence showed a higher mean IOP in the LTFC group [MD 0.76 mmHg], whereas low-quality meta-analysis showed higher IOP fluctuation [MD 1.09 mmHg] in the LTFC group.

CONCLUSIONS

LTFC is as effective as TTFC and DTFC, but worse than BiTFC in controlling mean IOP and IOP fluctuation for POAG or OHT patients. The quality of our meta-analyses was assessed as moderate, with the exception of one low-quality analysis that compared the IOP fluctuation of LTFC and BiTFC.

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.

Efficacy and tolerability of the fixed combinations latanoprost/timolol versus dorzolamide/timolol in patients with elevated intraocular pressure: a meta-analysis of randomized controlled trials

Objective

To evaluate the efficacy and tolerability of the fixed combination of Latanoprost/Timolol versus Dorzolamide/Timolol in the treatment of patients with elevated intraocular pressure (IOP).

Methods

A comprehensive literature meta-analysis was performed according to the Cochrane Collaboration methodology to identify randomized clinical trials comparing latanoprost/timolol FC (FCLT) with dorzolamide/timolol (FCDT) in patients with elevated IOP. The efficacy estimates were measured by the weight mean difference (WMD) for the IOP reduction (IOPR) from baseline to end point, including the diurnal mean IOPR, 8 AM IOPR, 12 PM IOPR, and 4 PM IOPR. The tolerability estimates were measured by RR for adverse events. All outcomes were reported with a 95% confidence interval (CI). The data were synthesized by Stata 12.0 SE for Windows.

Results

Eight studies involving 841 patients (841 eyes) were included in the meta-analysis. With a WMD of IOPR in the diurnal mean of 0.16 mmHg (95% CI, -0.31 to 0.63), the FCLT was as effective as FCDT in lowering IOP in patients with elevated IOP (P = 0.51). The WMDs of IOPR were 0.58 mmHg (95% CI: -0.002 to 1.17) at 8 AM, -0.07 mmHg (95% CI: -0.50 to 0.36) at 12 PM, and 0.41 mmHg (95% CI: -0.18 to 1.00) at 4 PM, and there were no significant difference between FCLT and FCDT. FCLT was associated with a significantly lower incidence of eye pain, bitter taste, and irritation/stinging than FCDT, with pooled RRs of 0.34 (95% CI: 0.14 to 0.82), 0.06 (95% CI:0.008 to 0.42), and 0.35 (95% CI: 0.14 to 0.85), respectively.

Conclusion

FCLT was associated with equivalent efficacy in IOP lowering comparing with FCDT. However, FCLT was better tolerated than FCDT.

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.

Additive intraocular pressure-lowering effect of dorzolamide 1%/timolol 0.5% fixed combination on prostaglandin monotherapy in patients with normal tension glaucoma

Purpose

To evaluate the intraocular pressure (IOP)-lowering effect of adding dorzolamide 1.0%/timolol 0.5% fixed combination (DTFC) to prostaglandin analogs (PGAs) as monotherapy in patients with normal tension glaucoma.

Methods

A prospective, clinical, case-controlled study of patients with normal tension glaucoma. Patients had been on a once-daily night dose of prostaglandins (PGs) as monotherapy and then received DTFC added to PGs for 8 weeks. The IOP was measured at 9 am, week 0 (baseline), week 4, and week 8.

Results

The baseline IOP of 40 patients who had previously been treated by prostaglandin monotherapy was 15.6 ± 2.0 mmHg at baseline. The IOPs at 4 and 8 weeks after adding DTFC to PGs were 13.5 ± 2.1 mmHg and 13.7 ± 2.2 mmHg, respectively. Significant decrease of the IOP was observed at each time point of measurement as compared with the baseline IOP before adding DTFC (P = 0.01). The percent IOP reduction from the baseline IOP at week 4 and week 8 was 13.5% ± 12.3% and 11.7% ± 13.1%, respectively. The percentage of patients who achieved 10% or more IOP reduction from the baseline IOP at week 8 was 62.5%. The baseline IOP was significantly correlated with the percent IOP reduction at week 8 (P = 0.03, r = 0.34).

Conclusion

DTFC therapy added to PGAs as glaucoma monotherapy is effective in patients with normal tension glaucoma.

Rational use of the fixed combination of dorzolamide - timolol in the management of raised intraocular pressure and glaucoma

Glaucoma is a multifactorial optic neuropathy in which the main therapeutic target is lowering of intraocular pressure (IOP) in order to retard the progression of existing structural and functional damage. The three mainstays of treatment are pharmacologic, laser, and surgical. The primary standard therapy in patients with open-angle glaucoma or ocular hypertension is topical medication. When monotherapy does not adequately lower the intraocular pressure, one or more agents are added or substituted. Combination pharmacotherapy such as Cosopt^® is available to improve efficacy and simplify medication regimen. A fixed combination of two ocular hypotensive drugs (the carbonic anhydrase inhibitor dorzolamide and the beta-adrenoceptor antagonist timolol), Cosopt^® is indicated for the treatment of elevated IOP in patients with open-angle glaucoma or ocular hypertension insufficiently responsive to topical beta-adrenoceptor antagonist monotherapy. Compared with concomitant therapy with the individual components, the primary advantage of fixed combination dorzolamide – timolol is convenience, which may also improve compliance. Clinical trials have demonstrated that the fixed combination dorzolamide – timolol is safe, effective and generally well tolerated in lowering IOP in patients with open angle glaucoma or ocular hypertension, including individuals uncontrolled on beta-adrenoceptor antagonist or other monotherapy.

Safety, tolerability, and efficacy of fixed combination therapy with dorzolamide hydrochloride 2% and timolol maleate 0.5% in glaucoma and ocular hypertension

Glaucoma is a collection of diseases characterized by multifactorial progressive changes leading to visual field loss and optic neuropathy most frequently due to elevated intraocular pressure (IOP). The goal of treatment is the lowering of the IOP to prevent additional optic nerve damage. Treatment usually begins with topical pharmacological agents as monotherapy, progresses to combination therapy with agents from up to 4 different classes of IOP-lowering medications, and then proceeds to laser or incisional surgical modalities for refractory cases. The fixed combination therapy with the carbonic anhydrase inhibitor dorzolamide hydrochloride 2% and the beta blocker timolol maleate 0.5% is now available in a generic formulation for the treatment of patients who have not responded sufficiently to monotherapy with beta adrenergic blockers. In pre- and postmarketing clinical studies, the fixed combination dorzolamide–timolol has been shown to be safe and efficacious, and well tolerated by patients. The fixed combination dorzolamide–timolol is convenient for patients, reduces their dosing regimen with the goal of increasing their compliance, reduces the effects of “washout” when instilling multiple drops, and reduces the preservative burden by reducing the number of drops administered per day.

Efficacy, safety and tolerability of combination therapy with timolol and dorzolamide in glaucoma and ocular hypertension

Combination pharmacotherapy has simplified and improved glaucoma medication regimens. This update focuses on the previous and recent studies on efficacy and tolerability profile of dorzolamide–timolol in adult ocular hypertension and open angle glaucoma patients. Dorzolamide–timolol has been shown to be efficacious and well tolerated in clinical trials and the adverse effects reflect those of the individual components.

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.

Efficacy and safety of fixed combinations of latanoprost/timolol and dorzolamide/timolol in open-angle glaucoma or ocular hypertension

AIMS

To compare intraocular pressure (IOP) reductions with fixed-combination (FC) latanoprost/timolol once daily in the evening vsFC dorzolamide/timolol twice daily.

METHODS

This evaluator-masked, multicentre, controlled clinical trial randomized subjects with primary open-angle glaucoma or ocular hypertension with IOP insufficiently responsive to beta-blocker therapy (screening IOP>21 and <37 mm Hg) to FC latanoprost-timolol (N=135) or FC dorzolamide/timolol (N=135). At screening, baseline, and after 4 and 12 weeks of therapy, IOP was measured three times at 0800, 1200, and 1600 hours. Adverse events were recorded at each visit. The primary efficacy end point was whether either FC could be shown to be inferior to the other with respect to change in mean daytime IOP from baseline to week 12.

RESULTS

Mean daytime IOP levels were similar at baseline. Mean reductions in daytime IOP from baseline to week 12 were -9.7 mm Hg for FC latanoprost-timolol and -9.5 mm Hg for FC dorzolamide/timolol. The difference between FC latanoprost/timolol-FC dorzolamide-timolol was -0.2 mm Hg (95% confidence interval (CI), -0.8 to -0.4 mm Hg). The upper bound of the 95% CI was <1.5 mm Hg, indicating that neither FC is inferior to the other. However, a significantly greater percentage of subjects treated with FC latanoprost/timolol achieved IOP levels<or=16 and <or=15 mm Hg (P<or=0.01). Both treatments were well tolerated.

CONCLUSIONS

When beta-blocker therapy is inadequate, either FC may achieve the desired IOP level, but FC latanoprost/timolol more often achieves a pressure of <or=16 mm Hg. Both FCs were well tolerated.

Reporting of noninferiority and equivalence randomized trials for major prostaglandins: a systematic survey of the ophthalmology literature

BACKGROUND

Standards for reporting clinical trials have improved the transparency of patient-important research. The Consolidated Standards of Reporting Trials (CONSORT) published an extension to address noninferiority and equivalence trials. We aimed to determine the reporting quality of prostaglandin noninferiority and equivalence trials in the treatment of glaucoma.

METHODS

We searched, independently and in duplicate, 6 electronic databases for eligible trials evaluating prostaglandins. We abstracted data on reporting of methodological criteria, including reporting of per-protocol [PP] and intention-to-treat [ITT] analysis, sample size estimation with margins, type of statistical analysis conducted, efficacy summaries, and use of hyperemia measures.

RESULTS

Trials involving the four major prostaglandin groups (latanoprost, travoprost, bimatoprost, unoprostone) were analyzed. We included 36 noninferiority and 11 equivalence trials. Seventeen out of the included 47 trials (36%, 95% Confidence Intervals [CI]: 24-51) were crossover designs. Only 3 studies (6%, 95% CI: 2-17) reported a presented results of both ITT and PP populations. Twelve studies (26%, 95% CI: 15-39) presented only ITT results but mentioned that PP population had similar results. Thirteen trials (28%, 95% CI: 17-42) presented only PP results with no mention of ITT population results while 17 studies (36%, 95% CI: 24-51) presented only ITT results with no mention of PP population results. Thirty-four (72%, 95% CI: 58-83) of studies adequately described their margin of noninferiority/equivalence. Sequence generation was reported in 22/47 trials (47%, 95% CI: 33-61). Allocation concealment was reported in only 10/47 (21%, 95% CI: 12-35) of the trials. Thirty-five studies (74%, 95% CI: 60-85) employed masking of at least two groups, 4/47 (9%, 95% CI: 3-20) masked only patients and 8/47 (17%, 95% CI: 9-30) were open label studies. Eight (17%, 95% CI: 9-30) of the 47 trials employed a combined test of noninferiority and superiority. We also found 6 differing methods of evaluating hyperemia.

CONCLUSION

The quality of reporting noninferiority/equivalency trials in the field of glaucoma is markedly heterogeneous. The adoption of the extended CONSORT statement by journals will potentially improve the transparency of this field.

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.

Effectiveness and Safety of Dorzolamide – Timolol Alone or Combined with Latanoprost in Open-Angle Glaucoma or Ocular Hypertension

BACKGROUND:

Treatment of glaucoma is aimed at reducing intraocular pressure (IOP) to prevent further damage to the optic nerve. For patients who do not respond to monotherapy, combination treatment may be effective in achieving therapeutic reduction or target IOP.

OBJECTIVE:

To evaluate the effectiveness and safety of dorzolamide 2% with timolol 0.5% alone or combined with latanoprost in reducing IOP in a real-world setting.

METHODS:

A prospective, open-label, multicenter, nonrandomized interventional study was designed. Three hundred fifty patients with primary open-angle glaucoma or ocular hypertension and uncontrolled IOP after latanoprost monotherapy for 4 or more weeks were treated with combination dorzolamide–timolol twice daily added to their existing latanoprost therapy (D/T-Add-On; n = 280) or dorzolamide–timolol twice daily monotherapy (D/T-Switch; n = 70). The primary effectiveness outcome measure was the change in IOP after 6 and 12 weeks of treatment.

RESULTS:

Of the total population, 313 patients completed this trial (248 D/T-Add-On; 65 D/T-Switch). After 12 weeks, the mean ± SD IOP decrease was −6.3 ± 3.6 mm Hg (–28.1%) and −5.8 ± 4.9 mm Hg (–23.5%) in the D/T-Add-On and D/T-Switch groups, respectively (both p < 0.001). Therapeutic response rates (defined as IOP reduction >20%) after 12 weeks of treatment for the D/T-Add-On and the D/T-Switch groups were 66.4% (186/280) and 52.9% (37/70), respectively. There were 116 predominantly mild, nonserious adverse events attributed to the study drugs, reported by 86 (24.6%) patients. The most frequent adverse events were eye irritation (n = 42; 12.0%) and taste perversion (n = 15; 4.3%). No serious adverse events related to the study medications were reported.

CONCLUSIONS:

In patients with primary open-angle glaucoma or ocular hypertension and elevated IOP while on monotherapy with latanoprost, switching to dorzolamide–timolol or combining dorzolamide–timolol with latanoprost are effective and safe treatment options for reducing IOP and achieving therapeutic response.

Topical dorzolamide 2%/timolol 0.5% ophthalmic solution: a review of its use in the treatment of glaucoma and ocular hypertension

Topically administered dorzolamide 2%/timolol 0.5% (dorzolamide/timolol ophthalmic solution; Cosopt) is a fixed combination of two ocular hypotensive drugs (the carbonic anhydrase inhibitor dorzolamide and the beta-adrenoceptor antagonist timolol) that have an additive effect on lowering intraocular pressure (IOP) when administered together. This product is indicated for the treatment of elevated IOP in patients with open-angle glaucoma or ocular hypertension (OH) who are insufficiently responsive to topical beta-adrenoceptor antagonist monotherapy. As such, it can be considered for use in individuals who, as a consequence of failing to achieve target IOP with beta-adrenoceptor antagonist monotherapy, require the addition or substitution of another class of topical antiglaucoma medication. Clinical trials have demonstrated that dorzolamide/timolol (1 drop per eye twice daily) is an effective and generally well tolerated fixed combination for lowering IOP in patients with open angle glaucoma or OH, including individuals uncontrolled on beta-adrenoceptor antagonist monotherapy. Compared with concomitant therapy with the individual components, the primary advantage of fixed combination dorzolamide/timolol is convenience.

Circadian Intraocular Pressure Control with Dorzolamide versus Timolol Maleate Add-On Treatments in Primary Open-Angle Glaucoma Patients Using Latanoprost

PURPOSE

To compare the 24-hour efficacy of dorzolamide and timolol maleate administered twice daily to primary open-angle glaucoma patients whose intraocular pressure (IOP) could not be adequately controlled with latanoprost monotherapy.

METHODS

In this double-blind prospective crossover clinical comparison trial, 36 primary open-angle glaucoma patients with uncontrolled IOP despite treatment with latanoprost applied once daily were administered timolol and dorzolamide twice daily. The treatment sequence was randomized. All patients underwent measurements for four 24-hour tonometric curves: at baseline and after each 4-week period of treatment. The IOP measurements were taken at 06:00, 09:00, 12:00, 15:00, 18:00, 21:00, 24:00 and 03:00 h. The between-group differences were tested for significance by means of parametric analysis of variance at each time point and circadian curve. The peak values within circadian curve were defined. The mean of the exact amount and percentage of additional IOP reductions from baseline were evaluated and success rates (a minimum of 10% reduction) were determined for both drug regimens.

RESULTS

The mean peak/circadian curve IOPs were 23.4 +/- 2.2/21.8 +/- 2.2 mm Hg at dorzolamide baseline, 23.3 +/- 2.2/21.7 +/- 2.1 mm Hg at timolol baseline, and reduced to 20.2 +/- 1.7/18.7 +/- 1.7 mm Hg and 20.7 +/- 2.4/19.4 +/- 1.6 mm Hg, respectively. When added to latanoprost, both dorzolamide and timolol lowered IOP at circadian curve significantly (p < 0.05). Dorzolamide reduced baseline IOP values at each time point. Timolol also significantly reduced baseline IOP values at all time points except at 03:00. The mean of the exact amount and percentage of reduction in IOP at circadian curve and 5 out of 8 time points were significantly greater with dorzolamide add-on treatment (p < 0.05). The successful reduction rates were 86% for the dorzolamide group and 61% for the timolol group (p = 0.016; chi(2) test).

CONCLUSION

Both of the combinations are effective in lowering IOP, the exact amount and percentage of reduction is greater with the latanoprost + dorzolamide regimen, especially at night-time.

24-h IOP control with latanoprost, travoprost, and bimatoprost in subjects with exfoliation syndrome and ocular hypertension

PURPOSE

To compare the 24-h IOP reductions induced by latanoprost, travoprost, and bimatoprost in eyes with exfoliation syndrome (XFS) associated with ocular hypertension (OH).

METHODS

This was a prospective, randomized, single masked, and parallel design study with 15 patients in each treatment group. After washout of any previous medications, each patient underwent a baseline 24-h IOP curve testing at 0600, 0900, 1200, 1500, 1800, 2100, and at 2400 (midnight) hours. Patients were then randomized to receive latanoprost, travoprost, or bimatoprost once a day for 3 months. The 24-h curve testing was repeated at first week, and first and third months.

RESULTS

Maximal and minimal IOP was recorded at 0600 and 1800-2100 hours. There was no significant difference among treatment groups at any time-point except for the first week. At the first week, the travoprost group had significantly lower IOP levels than the latanoprost and bimatoprost groups. All medicines significantly lowered 24-h IOP from baseline (P=0.001 for each). Although there was no significant difference in IOP reduction among groups at first week and first month, bimatoprost reduced the 24-h IOP (7.9+/-1.4) more than travoprost (6.6+/-0.5) at the end of the third month (P=0.003). The mean 24-h range of IOP was lowest with travoprost in all visits, and between-group differences was significant for travoprost vslatanoprost (P=0.007) and travoprost vsbimatoprost (P=0.001) at the third month.

CONCLUSION

Latanoprost, travoprost, and bimatoprost were effective in reducing the 24-h IOP in patients with XFS and OH, and more research is required with a larger study.

Cost considerations of the new fixed combinations for glaucoma medical therapy

OBJECTIVE

To compare the costs of the new fixed combinations for glaucoma medical therapy.

METHODS

The studied drugs were: Cosopt (5-mL bottle), Combigan (5-mL bottle) and Xalacom (2.5-mL bottle). Five bottles of each drug were obtained from pharmacies, and the medications lot numbers were recorded. To calculate the drop volume, 10 drops and 1 mL of each bottle were weighed with a digital precision scale. Drop volume was calculated by the relation between volume and weight. The cost of each bottle of medication was determined from the average retail price in Canada. The prices were obtained in Canadian dollars (dollars).

RESULTS

The drops of Cosopt (39.60 +/- 0.45 microL) were considerably larger than the drops of Combigan (33.75 +/- 0.60 microL) and Xalacom (30.87 +/- 0.37 microL). The average number of drops per millilitre varied from 25.25 +/- 0.29 (Cosopt) to 32.40 +/- 0.39 microL (Xalacom). Combigan presented the lowest daily cost (dollars 0.87 +/- 0.02) followed by Xalacom (dollars 1.09 +/- 0.01) and Cosopt (dollars 1.22 +/- 0.01). The average cost by year varied from dollars 316.75 +/- 5.59 (Combigan) to dollars 445.96 +/- 5.16 (Cosopt), with a total difference of dollars 129.21 per year of treatment.

CONCLUSIONS

There was a statistically significant difference in average drop size and cost among the three studied drugs. Combigan presented the lowest daily cost followed by Xalacom and Cosopt.