A randomized trial in patients inadequately controlled with timolol alone comparing the dorzolamide-timolol combination to monotherapy with timolol or dorzolamide. Dorzolamide-Timolol Combination Study Group

The treatment of glaucoma using topical preservative-free agents: an evaluation of safety and tolerability

Introduction: Preservative-free (PF) medications represent a valuable treatment strategy in the lifelong management of glaucoma. By removing preservative toxicity, PF formulations provide tangible clinical benefits to glaucoma patients worldwide. They improve tolerability and adherence, leading to a positive impact in long-term intraocular pressure (IOP) control.Areas covered: A critical review of the subject is provided, including selected evidence on the safety and tolerability of currently available topical PF formulations. Cumulative evidence confirms that topical PF medications are at least equally efficacious to their preserved equivalents. There is convincing short-term evidence for superior tolerability and safety of PF formulations compared to preserved medications. The long-term benefits and success of PF therapy requires further elucidation.Expert opinion: Successful stepwise administration of medical therapy for glaucoma remains elusive. There is a greater risk for ocular toxicity and therapy failure with preserved topical glaucoma therapy. Currently available and emerging PF therapy options potentially optimize lifelong stepwise glaucoma therapy and may enhance outcome. To avert complications from preservatives leading to poor adherence, ideally, future antiglaucoma therapy should become 100% PF. There are still key aspects of PF therapy that warrant further investigation.

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

MOF-Based Polymeric Nanocomposite Films as Potential Materials for Drug Delivery Devices in Ocular Therapeutics

Novel MOF-based polymer nanocomposite films were successfully prepared using Zr-based UiO-67 as a metal-organic framework (MOF) and polyurethane (PU) as a polymeric matrix. Synchrotron X-ray powder diffraction (SXRPD) analysis confirms the improved stability of the UiO-67 embedded nanocrystals, and scanning electron microscopy images confirm their homogeneous distribution (average crystal size ∼100-200 nm) within the 50 μm thick film. Accessibility to the inner porous structure of the embedded MOFs was completely suppressed for N₂ at cryogenic temperatures. However, ethylene adsorption measurements at 25 °C confirm that at least 45% of the MOF crystals are fully accessible for gas-phase adsorption of nonpolar molecules. Although this partial blockage limits the adsorption performance of the embedded MOFs for ocular drugs (e.g., brimonidine tartrate) compared to the pure MOF, an almost 60-fold improvement in the adsorption capacity was observed for the PU matrix after incorporation of the UiO-67 nanocrystals. The UiO-67@PU nanocomposite exhibits a prolonged release of brimonidine (up to 14 days were quantified). Finally, the combined use of SXRPD, thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) analyses confirmed the presence of the drug in the nanocomposite film, the stability of the MOF framework and the drug upon loading, and the presence of brimonidine in an amorphous phase once adsorbed. These results open the gate toward the application of these polymeric nanocomposite films for drug delivery in ocular therapeutics, either as a component of a contact lens, in the composition of lacrimal stoppers (e.g., punctal plugs), or in subtenon inserts.

Management Of Glaucoma In Developing Countries: Challenges And Opportunities For Improvement

Glaucoma is the leading cause of blindness in the developed and developing world. Not only is the clinical impact of this disease considerable, but associated economic and humanistic burdens – affecting patients, caregivers, and society – are substantial. Since glaucoma is an age-related disorder and populations in many developing countries are aging at a faster pace than in the developed world, increasing attention is being focused on ways to ameliorate the burdens of illness. In this paper, we examine the burdens of glaucoma with particular focus on developing countries, discuss some of the challenges that exist in delivering optimal glaucoma management within budget constraints, and bring into perspective how we could improve current healthcare systems, leverage technology, and strike an appropriate balance between cost and quality of care, thereby offering considerations to payors and policymakers in these countries that may result in longer-term cost savings, while concurrently striving to achieve the WHO Vision on the prevention of blindness and visual impairment.

Glaucoma: Current treatment and impact of advanced drug delivery systems

The human eye being a complex and a very sensitive organ makes the drug delivery task challenging. An increase in the intra-ocular pressure at the aqueous humour leads to glaucoma which is not only indecipherable but can also be the reason of blindness for many. The presently available marketed formulations using anti-glaucoma drugs have issues of either difficulty in crossing the blood- retinal barrier or lower systemic bioavailability. Hence, the drugs having lower therapeutic index would need to be administered frequently, which eventually lead to deposition of concentrated solutions at ocular site, producing toxic effects and cellular damage to the eye. To overcome these drawbacks the novel drug delivery systems like In-situ gels, liposomes, niosomes, hydrogel, dendrimers, nanoparticles, solid lipid nanoparticles, Microneedles or ocular inserts play an important role to enhance the therapeutic efficacy of the anti-glaucomic drugs. The present review briefs the current treatments in terms of drugs used and in detail the impact of utilizing the above mentioned novel drug delivery systems in the treatment of glaucoma.

Fixed-dose combination of AR-13324 and latanoprost: a double-masked, 28-day, randomised, controlled study in patients with open-angle glaucoma or ocular hypertension

BACKGROUND/AIMS

To evaluate the ocular hypotensive efficacy of fixed-dose combinations of the Rho kinase inhibitor and norepinephrine transport inhibitor AR-13324 (0.01% and 0.02%) and latanoprost (PG324 Ophthalmic Solution) relative to the active components AR-13324 0.02% and latanoprost 0.005%, used bilaterally at night.

METHODS

This was a double-masked, randomised, parallel comparison study in patients with open-angle glaucoma or ocular hypertension. After washout, patients were randomised to one of four treatment arms and treated for 28 days. The primary efficacy variable was mean diurnal intraocular pressure (IOP) at day 29.

RESULTS

We randomised 298 patients, of whom 292 (98%) completed the study. Mean unmedicated diurnal IOPs (study eye) was 25.1, 25.1, 26.0 and 25.4 in the PG324 0.01%, PG324 0.02%, latanoprost and AR-13324 0.02% groups, respectively. On day 29, mean diurnal IOP decreased to 17.3, 16.5, 18.4 and 19.1 mm Hg, respectively. For the primary efficacy variable of mean diurnal IOP at day 29, PG324 0.02% met the criterion for statistical superiority relative to both latanoprost and AR-13324 0.02% (p<0.0001), providing additional IOP lowering of 1.9 and 2.6 mm Hg, respectively. PG324 0.01% also met the criterion for superiority. The most frequently reported adverse event was conjunctival hyperaemia with an incidence of 41% (30/73), 40% (29/73), 14% (10/73) and 40% (31/78) in the PG324 0.01%, PG324 0.02%, latanoprost and AR-13324 0.02% groups, respectively.

CONCLUSIONS

In this short-term study, the fixed-dose combination of AR-13324 0.02% and latanoprost 0.005% in PG324 Ophthalmic Solution provides clinically and statistically superior ocular hypotensive efficacy relative to its individual active components at the same concentrations. The only safety finding of note was transient asymptomatic conjunctival hyperaemia which was typically of mild severity.

TRIAL REGISTRATION NUMBER

NCT02057575.

Effect of dorzolamide-timolol fixed combination prophylaxis on intraocular pressure spikes after intravitreal bevacizumab injection

AIM

To evaluate the effect of topical dorzolamide-timolol fixed combination prophylaxis on short term intraocular pressure (IOP) changes in patients who had intravitreal bevacizumab injection.

METHODS

One hundred and fifty one eyes of 151 patients which were followed up in retina clinic in Ulucanlar Eye Training and Research Hospital were evaluated in this study. Patients were divided into two groups. Group 1 consists of 75 patients who had topical dorzolamid-timolol medication two hours before injection; while Group 2 consists of 76 patients without prophylaxis. Demographic data, IOP measurements prior to the injection and one, thirty and sixty minutes and twenty-four hours after the injection were recorded. The data were analyzed using SPSS software version 15.0 (SPSS Inc., Chicago, IL, USA).

RESULTS

There were no significant difference between two groups in age, gender distrubition and indications for injections. The mean IOPs in Groups 1 and 2 prior to the injection (T0) were 17.84±0.43 and 18.15±0.43 mm Hg, one minute after the injection (T1) were 29.75±1.6 and 34.44±1.59 mm Hg, 30min after the injection (T30) were 20.06±0.6 and 21.71±0.59 mm Hg respectively. The mean IOPs were 18.26±0.56 mm Hg in Group 1 and 19.78±0.56 mm Hg in Group 2 sixty minutes after the injection (T60). All IOP values after the injection were compared between two groups, there was a significant difference between two groups only on T1; one minute after the injection (P=0.04). There were a statiscially significant difference between the baseline values and other recorded values; except on T60, in Groups 1 and 2 (P<0.05).

CONCLUSION

After intravitreal bevacizumab injection; we observe a transient IOP elevation which normalizes about one hour after intravitreal injection. In patients who had topical dorzolamid-timolol combination prophylaxis before injections, a significant decrease is seen in IOP spikes due to this injection. The appropiate approach will monitor IOP after intravitreal injection and evaluate the using prophylactic antiglaucomatous drugs before the injection in patients with ganglion nerve cell damage.

The impact of timolol maleate on the ocular tolerability of fixed-combination glaucoma therapies

Glaucomatous optic atrophy is the second most common cause of blindness worldwide, and lowering intraocular pressure (IOP) is the only proven method to slow or stop the progression of the disease. Approximately 40% of patients with elevated IOP will require more than one medication to obtain a modest 20% reduction in IOP, and as a result, some patients may require two medications, provided in either two separate bottles or in one bottle with the use of fixed-combination therapies. Each therapy has its own unique safety and efficacy profile. Topical beta-blockers have a particularly favorable ocular-tolerability profile, and several studies of fixed-combination medications containing the beta-blocker timolol maleate have shown a lower prevalence of some ocular adverse events for the fixed-combination therapy compared to the non-beta-blocker individual component. In this review, we examined clinical data pertaining to the ocular surface tolerability of fixed-combination medications containing timolol maleate in comparison to the individual components. In particular, preference was given to prospective, randomized, multicenter trials of 3 months in duration or longer that compared a fixed-combination therapy to monotherapy with the individual components. A review of the literature revealed that some fixed-combination therapies can provide a reduced risk of common side effects compared to their individual components, with conjunctival hyperemia and ocular allergy being less frequent in some timolol-containing fixed-combination therapies. This effect appears to be most significant for latanoprost 0.005%, bimatoprost 0.03%, and brimonidine 0.2%.

Improvement in glaucoma patient quality of life by therapy switch to preservative-free timolol/dorzolamide fixed combination

PURPOSE

To assess a change in visual-related quality of life (QoL) in glaucoma patients after switching from preservative-containing medical therapy to preservative-free unit dose timolol/dorzolamide fixed combination (TDFC UD).

METHODS

Prospective, noninterventional, multicenter 8-week study. Primary outcome was a change in visual symptoms at week 8, as assessed by the Glaucoma Symptom Scale (GSS).

RESULTS

80 patients completed the study. There was a clinically significant increase in the scores of all GSS-related categories at week 8 when compared to baseline (GSS symptom week 8: +21.15 ± 37.9%, GSS function week 8: +10.3 ± 31.6%, both p < 0.001 vs. baseline). Comparison between patients taking only TDFC UD and patients taking TDFC UD plus concomitant medications did not detect differences in any GSS category (p > 0.50 in all comparisons).

CONCLUSIONS

Switching to TDFC UD significantly improved the self-reported QoL of glaucoma patients. This can be seen even in patients who are taking concomitant ocular treatments.

Clinical options for the reduction of elevated intraocular pressure

Elevated IOP in clinical practice is usually seen in glaucoma or ocular hypertension. Glaucoma affects 60 million people worldwide and 8.4 million are bilaterally blind from this chronic disease.1 Options for reducing IOP rely on pharmacological agents, laser treatments and surgery which may be penetrating or non-penetrating. The last twenty years has seen significant changes in all of these strategies. This review aims to cover these clinical options and introduce some of the new technologies currently in development for the clinical lowering of IOP.

Intraocular pressure reduction of fixed combination timolol maleate 0.5% and dorzolamide 2% (Cosopt) administered three times a day

Purpose

To evaluate the safety and efficacy in intraocular pressure (IOP) reduction of increasing Cosopt dosage from twice to three times a day.

Methods

The study included patients with primary open-angle glaucoma or ocular hypertension. After a washout period, IOP was measured at baseline, after 4 weeks of treatment with Cosopt twice a day, and after another 4 weeks of treatment with Cosopt three times a day. Blood pressure, heart rate, and oxygen saturation levels were also recorded.

Results

Twenty-nine eyes of 29 patients were included. Increasing Cosopt dosage resulted in a statistically significant (P < 0.001) additional reduction in IOP of 2.2 ± 1.58 mmHg (10.69% ± 7.49% of the baseline IOP values). There were no local or systemic adverse effects.

Conclusion

Treatment with Cosopt three times a day was more effective in reducing IOP than twice a day, with no effect on safety.

The management of glaucoma and intraocular hypertension: current approaches and recent advances

In the last decade, numerous novel ocular hypotensive agents have been introduced for the control of intraocular pressure (IOP). Clinicians now have more options than ever in the selection of medical therapy for the treatment of glaucoma and ocular hypertension. When selecting an ocular hypotensive medication for their patients, clinicians should consider not only the IOP-lowering efficacy of an agent, but also the ability of the drug to allow patients to achieve target levels of IOP that are low enough to stop the progression of glaucomatous damage. Other considerations should include how well the drug controls diurnal IOP, the likelihood of serious adverse events, the versatility of the medication for use as an adjunctive agent, as well as other potential attributes (ie, neuroprotection).

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.

Fixed combination of topical brimonidine 0.2% and timolol 0.5% for glaucoma and uncontrolled intraocular pressure

Lowering IOP is the most readily modifiable risk factor to delay the development and progression of glaucoma (POAG). The fixed combination of brimonidine tartrate 0.2% and timolol maleate 0.5% (FCBT) combines a highly selective α2-adrenergic agonist (brimonidine) with a non-selective β-blocker (timolol). FCBT reduces aqueous production and enhances uveoscleral outflow. Concomitant brimonidine and timolol have additive effects on reducing intraocular pressure (IOP). Multi-center randomized control trials have documented superiority of FCBT twice daily on IOP control compared with monotherapy with the individual components, and equal efficacy compared with concomitant therapy. IOP reduction with FCBT versus fixed combination dorzolamide 2% and timolol 0.5% (FCDT) was similar in a small study. Other studies (n > 293) evaluating concomitant brimonidine and timolol have shown that it is not inferior to FCDT. However, concomitant brimonidine and timolol administered twice daily was significantly less efficacious in IOP reduction than fixed combination latanoprost 0.005% and timolol 0.5% (FCLT). There are no published studies comparing FCBT with FCLT. The side effect profile for FCBT reflects that of its individual components. FCBT was generally well tolerated, with less ocular side effects than brimondine alone, but more than timolol alone. Documented systemic effects were few, although this could be confounded by selection bias. FCBT is a safe and effective IOP lowering agent for POAG and ocular hypertension.

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.

Effectiveness of dorzolamide–timolol (COSOPT) in patients who were treatment naive for open-angle glaucoma or ocular hypertension: the COSOPT first-line study

PURPOSE

The aim of this study was to assess the effectiveness of dorzolamide-timolol (DT) in the management of open-angle glaucoma (OAG) and ocular hypertension.

METHODS

An open-label, 12-week, multicenter, Canadian study was conducted. Patients with untreated OAG or ocular hypertension received DT for 12 weeks to reduce intraocular pressure (IOP). If target IOP was not reached after the first 6-week treatment period, a prostaglandin (PG) (latanoprost) was added for the remaining 6 weeks. Primary outcome measures were changes in IOP from baseline to 6 and 12 weeks of treatment, and secondary outcome measures included the proportion of patients achieving target IOP and the proportion of patients achieving therapeutic response defined as a reduction of 5.0 mmHg or 20% in IOP from baseline. IOP values were the mean of 2 measures taken before and at least 2 h after patients administered the study medication.

RESULTS

A total of 164 patients were enrolled. Mean [standard deviation (SD)] population age was 63.0 (12.3) years and 53.0% of the patients were men. At week 6, the mean (SD) absolute and percent change in IOP for the total population was (-11.1) (4.9) and (-36.4)% (13.9%), respectively, and 92.1% of the patients achieved a reduction in IOP of at least 5 mmHg. Therapeutic target was achieved by 136 (82.9%) patients (DT subgroup) at 6 weeks, whereas 28 (17.1%) patients were changed to a combination therapy of DT and latanoprost [DT plus PG (DT & PG) subgroup]. Between weeks 6 and 12, DT was effective in sustaining the IOP within therapeutic target, whereas addition of latanoprost reduced the IOP of the DT & PG subgroup by an additional 6.3 mmHg or 22.1% (20.1%). At week 12, patients in the DT subgroup experienced a clinically and statistically significant mean (SD) decrease in IOP from a baseline of 12.2 mmHg or 40.4% (11.9%) (P < 0.001), whereas these values corresponded to 13.4 mmHg and 39.7% (15.7%) (P < 0.001), respectively, in the DT & PG subgroup. The proportion of patients who achieved therapeutic response during the entire 12-week study period was over 82%. Treatment-related adverse events (AEs) were reported by 19 (14.0%) patients in the DT subgroup and by 6 (21.4%) patients in the combination subgroup. Eye disorders and nervous system disorders were among the most common treatment-related AEs in both subgroups. No serious AEs were reported during the study period.

CONCLUSION

DT alone and DT in combination with a PG are effective in significantly reducing IOP in patients with untreated OAG or ocular hypertension. The treatment was safe and well tolerated with a low incidence of AEs.

Predictors for visual field progression and the effects of treatment with dorzolamide 2% or brinzolamide 1% each added to timolol 0.5% in primary open-angle glaucoma

PURPOSE

This study aims to identify progression factors in patients with primary open-angle glaucoma (POAG), including the effects of treatment with dorzolamide 2% or brinzolamide 1%, each added to timolol 0.5%.

METHODS

A sample of 161 POAG patients were prospectively randomized to receive either dorzolamide 2% (DT) or brinzolamide 1% (BT) b.i.d., each added to timolol 0.5%, during a 60-month, evaluator-masked study. Progression was determined by perimetric criteria. Factors associated with visual field progression were estimated using a conditional Cox hazard model with patient intraclass correlation and were expressed as hazard ratios (HRs) with 95% confidence intervals (95% CIs).

RESULTS

Predictive baseline factors were lower diastolic blood pressure (DBP), lower mean arterial pressure (MAP), antihypertensive treatment, lower end-diastolic velocity (EDV) in the ophthalmic artery (OA) and short posterior ciliary artery (SPCA), and a higher resistivity index (RI) in the OA and SPCA. Progression risk decreased by approximately 30% and 20% with each centimetre per second increase of EDV in the OA and SPCA, respectively, from baseline to the last follow-up visit. Each RI decrease (or increase) of 0.01 unit in the OA or SPCA was associated with an approximate 20% decrease (or increase) in risk for progression. In a multivariate analysis, progression risk was significantly lower in eyes treated with DT (HR=0.65, 95% CI 0.41-0.90) compared with those treated with BT.

CONCLUSIONS

Progression increased with lower DBP, lower MAP, antihypertensive medication, lower EDV in the OA and SPCA, and higher RI in the OA and SPCA. The risk for progression in patients treated with DT was half that in patients treated with BT.

Tolerability and effectiveness of preservative-free dorzolamide-timolol (preservative-free COSOPT) in patients with open-angle glaucoma or ocular hypertension

PURPOSE

To assess the effect of preservative-free dorzolamide-timolol on nonvisual symptoms and intraocular pressure (IOP) in newly diagnosed and untreated patients with open-angle glaucoma or ocular hypertension.

METHODS

This was a prospective, 8-week, open-label, Canadian multicenter study. All patients were treated with preservative-free dorzolamide-timolol formulation. The primary outcome was the change in the nonvisual symptom score of the Glaucoma Symptom Scale (GSS-SYMP-6) from baseline to 8 weeks. Secondary effectiveness outcome measures were absolute and percent changes in IOP from baseline to 4 and 8 weeks.

RESULTS

One hundred and seventy-eight patients were enrolled. Mean (SD) age was 65.6 (12.1) years and 90 (50.6%) were females. There were 92 patients diagnosed with open-angle glaucoma, 62 with ocular hypertension, and 23 with both diseases (diagnosis was missing for one patient). The mean (SD) GSS-SYMP-6 score increased from 73.6 (21.8) at baseline to 76.1 (20.7) at 8 weeks (P = 0.097). Mean (SD) IOP significantly decreased by 11.7 (5.1) mmHg at 4 weeks (P < 0.001) and by 11.5 (5.3) mmHg at 8 weeks (P < 0.001), representing reductions of -38.5% (P < 0.001) and -38.0% (P < 0.001), respectively.

CONCLUSION

Preservative-free dorzolamide-timolol does not increase eye discomfort while significantly reducing IOP in patients with open-angle glaucoma or ocular-hypertension.

Fixed combinations of dorzolamide-timolol and brimonidine-timolol in the management of glaucoma

IMPORTANCE OF THE FIELD

The emergence of fixed-combination drugs for the treatment of glaucoma has, to some extent, changed the medical management of glaucoma. The potential benefits of these drugs include a reduction in the total number of drops and preservatives instilled per day and improved patient comfort factors, which may contribute to better compliance. Combination medications may also improve therapeutic efficacy and play an important role in controlling medication cost. However, the fixed dosing may be a disadvantage in some cases.

AREA COVERED IN THIS REVIEW

This review describes the composition, pharmacokinetics, mode of action, efficacy, side effects, and safety profile of fixed-combination dorzolamide-timolol and fixed-combination brimonidine-timolol.

WHAT THE READER WILL GAIN

Understanding of the pros, cons, and safety profile of two FDA approved fixed-combination antiglaucoma medication.

TAKE HOME MESSAGE

Fixed-combination medications may be a reasonable adjunct to prostaglandins if a large drop in the intraocular pressure (IOP) is desired and adding only one medication is unlikely to reach the target IOP range. Both mentioned drugs are effective in reducing the IOP and further clinical studies will help identify differences in efficacy between the two. The clinician must make an individualized assessment of the medication's risk-benefit profile for each patient.

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.

Comparison of the efficacy and tolerability of preservative-free and preservative-containing formulations of the dorzolamide/timolol fixed combination (COSOPT™) in patients with elevated intraocular pressure in a randomized clinical trial

BACKGROUND

The aim of this study was to compare the efficacy and tolerability of preservative-free (PF) and preservative-containing (PC) formulations of the dorzolamide/timolol fixed combination (COSOPT™) in patients with elevated intraocular pressure (IOP).

METHODS

A parallel, randomized, double-masked study was conducted. After a 3-week run-in on timolol, patients with ocular hypertension, as confirmed by an IOP ≥22 mmHg, were randomized 1:1 to receive PF or PC dorzolamide/timolol twice daily for 12 weeks. IOP was measured at hour 0 (drug trough) and hour 2 (drug peak) at baseline (last day of 3-week timolol run-in), and weeks 2, 6 and 12.

RESULTS

A total of 261 patients were randomized. Mean baseline IOPs were 23.7 mmHg for both treatments at hour 0 and 21.2 mmHg for PF dorzolamide/timolol and 21.4 mmHg for PC dorzolamide/timolol at hour 2. At all study time points (trough and peak at weeks 2, 6, and 12), the difference between treatments in mean change from baseline IOP was <0.5 mmHg. The 95% confidence intervals for the estimated treatment difference (PF minus PC) in mean change from baseline IOP at week 12 was -0.86 to 0.23 mmHg for trough (primary endpoint) and -0.39 to 0.67 mmHg for peak (secondary endpoint). The most common adverse events were ocular burning/stinging, reported by 16.0% and 21.5% of patients receiving PF and PC dorzolamide/timolol respectively, and taste perversion, reported by 3.1% and 5.4% of patients receiving PF and PC dorzolamide/timolol respectively.

CONCLUSIONS

In patients with elevated IOP, PF and PC dorzolamide/timolol were equivalent in efficacy for change in trough and peak IOP, and had generally similar tolerability.

Update and critical appraisal of combined timolol and carbonic anhydrase inhibitors and the effect on ocular blood flow in glaucoma patients

Topical hypotensive therapy with both timolol and carbonic anhydrase inhibitors has been shown to be efficacious at reducing intraocular pressure. Many prospective studies have also suggested that carbonic anhydrase inhibitors augment ocular blood flow and vascular regulation independent of their hypotensive effects. Although consistent in their findings, these studies must be cautiously interpreted due to the limitations of study design and specific blood flow imaging modalities. The purpose of this review is to appraise and critically evaluate the current body of literature investigating the effects of combined treatment with topical carbonic anhydrase inhibitors and timolol in patients with glaucoma with respect to ocular blood flow, visual function, and optic nerve head structure.

Efficacy and tolerability of latanoprost compared to dorzolamide combined with timolol in the treatment of patients with elevated intraocular pressure: a meta-analysis of randomized, controlled trials

OBJECTIVE

The aim of this study was to evaluate the efficacy and tolerability of latanoprost, compared with the combination of dorzolamide and timolol, in the treatment of patients with elevated intraocular pressure (IOP).

METHODS

Pertinent randomized, controlled trials were identified through systematic searches of the Cochrane Library, PubMed, EMBASE, Chinese Biomedicine Database, and internet searches of meeting abstracts and the manufacturers' databases. The main efficacy measures were the IOP reduction (IOPR), including diurnal mean IOPR, and 10:00 IOPR. The main tolerability measure was withdrawal due to adverse events and individual adverse events.

RESULTS

Fourteen (14) studies involving 2149 patients were included in the meta-analysis. Latanoprost was significantly more effective in lowering diurnal mean IOP than combined dorzolamide and timolol in patients with IOP insufficiently controlled by timolol alone, with a weighted mean difference (WMD) for the diurnal mean IOPR% of 3.12 (95% confidence interval, 0.47-5.78) at 3 months, and latanoprost was as effective as the combination of dorzolamide and timolol in patients without baseline timolol treatment. The combination of dorzolamide and timolol was associated with numerically greater reductions in 10:00 IOP, compared with latanoprost in patients with or without timolol treatment at baseline: only the result in patients with baseline timolol treatment at 1 month was statistically significant (WMD -4.14: range, -5.78 to -2.50). The combination of dorzolamide and timolol was less tolerated than latanoprost, with pooled relative risk for withdrawals due to adverse events being 0.34 (range, 0.13-0.84).

CONCLUSIONS

Latanoprost was associated with significantly greater efficacy in lowering diurnal mean IOP than combined dorzolamide and timolol in patients with IOP insufficiently controlled by timolol alone, and latanoprost was as effective as combined dorzolamide and timolol in patients without baseline timolol treatment. The combination of dorzolamide and timolol was less tolerated than latanoprost.

A one-week comfort study of BID-dosed brinzolamide 1%/timolol 0.5% ophthalmic suspension fixed combination compared to BID-dosed dorzolamide 2%/timolol 0.5% ophthalmic solution in patients with open-angle glaucoma or ocular hypertension

PURPOSE

The aim of this study was to evaluate the ocular discomfort of brinzolamide 1%/timolol 0.5% ophthalmic suspension fixed combination dosed twice-daily compared to dorzolamide 2%/timolol 0.5% ophthalmic solution fixed combination dosed twice-daily.

METHODS

This was a prospective, double-masked, parallel-group, randomized, clinical trial. Patients had open-angle glaucoma or ocular hypertension and were randomized to twice-daily therapy with either brinzolamide 1%/timolol 0.5% or dorzolamide 2%/timolol 0.5%. Patients completed ocular discomfort assessments (based on burning, stinging, a feeling of heat or warmth, sharp pain, or smarting pain) on their current intraocular pressure-lowering therapy at baseline and on study medication after 1 week of dosing.

RESULTS

In the intent-to-treat analyses, mean ocular discomfort scores at 1 week were significantly lower in eyes receiving brinzolamide 1%/timolol 0.5% than dorzolamide 2%/timolol 0.5% (0.77 vs. 1.53; P = 0.0003). Mean increases from baseline in ocular discomfort scores were statistically significant in both groups but were smaller in eyes receiving brinzolamide 1%/timolol 0.5% (0.49; P = 0.0028) than dorzolamide 2%/timolol 0.5% (1.32; P < 0.0001). Over threefold more patients on brinzolamide 1%/timolol 0.5% (23/47, 49%) than dorzolamide 2%/timolol 0.5% (7/47, 15%) reported no ocular discomfort after 1 week of therapy (P = 0.0004).

CONCLUSIONS

Brinzolamide 1%/timolol 0.5% ophthalmic suspension is associated with a statistically significantly less ocular discomfort profile than dorzolamide 2%/timolol 0.5% ophthalmic solution.

Use of fixed-dose combination drugs for the treatment of glaucoma

Glaucoma is a leading cause of irreversible visual loss. This potentially blinding disease is a progressive optic neuropathy associated with elevated intraocular pressure (IOP). Initial therapy for glaucoma typically consists of topical medications or laser treatment to lower IOP. Frequently, more than one medication is required to achieve adequate control of IOP. However, more medications means more bottles and greater complexity for the patient. There are several potential benefits of fixed combination medications compared with using the individual components separately. These include a reduction in the total number of drops and preservative instilled per day, cost savings, improved tolerability and compliance and avoiding the washout effect resulting from rapid-sequence instillation of multiple drops. Attempts to develop effective fixed combinations of glaucoma medications date back several decades. In recent years, fixed combinations of commonly paired drugs have been approved by various regulatory bodies in different countries and have gained wide acceptance. Current commercially available, fixed combination drugs include the topical beta-adrenoceptor antagonist timolol 0.5% combined with a prostaglandin, a topical carbonic anhydrase inhibitor or an alpha-adrenoceptor agonist. Although there is no uniformity among registration trial designs, most published literature compares the efficacy of the fixed combination to the individual components and to concomitant use of both components. Various factors inherent to study design such as medication run-in, washout periods and peak and trough effects have to be taken into consideration when analysing the demonstrated efficacy of fixed combinations. Fixed combination treatments offer effective IOP control while reducing the washout effect and exposure to preservatives. They are also convenient. However, fixed combinations also remove the possibility of titrating the individual components both in terms of concentration and timing of administration. In addition, fixed combinations might not always provide the same efficacy as proper use of the individual components. The clinician must make individualised assessments when weighing the convenience of these medications against their limitations for specific patients.

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.

Intraocular pressure-lowering efficacy of brinzolamide 1%/timolol 0.5% fixed combination compared with brinzolamide 1% and timolol 0.5%

PURPOSE

To compare the safety and intraocular pressure (IOP)-lowering efficacy of brinzolamide 1%/timolol 0.5% fixed combination with brinzolamide 1% or timolol 0.5% alone in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT).

DESIGN

Randomized, double-masked, parallel group, multicenter study.

PARTICIPANTS

Five hundred twenty-three patients were randomized to the study treatments.

METHODS

Patients with OAG or OHT were recruited to the study. Qualifying eyes had IOPs of 24 to 36 mmHg at 8 am and 21 to 36 mmHg at 10 am on 2 eligibility visits after an appropriate washout period from previous treatment. Patients were assigned randomly to either brinzolamide 1%/timolol 0.5%, brinzolamide 1% (Azopt; Alcon Laboratories, Fort Worth, TX), or timolol 0.5%, dosed twice daily and were followed up while receiving therapy for 6 months. At selected sites, additional IOP measurements were performed at 12 pm, 4 pm, and 8 pm during the 2 eligibility visits, at month 3, and at month 6.

MAIN OUTCOME MEASURE

Mean IOP.

RESULTS

Brinzolamide 1%/timolol 0.5% produced statistically significant and clinically relevant reductions from baseline ranging from 8.0 to 8.7 mmHg, which were statistically and clinically superior to that of either brinzolamide 1% (5.1-5.6 mmHg) or timolol 0.5% (5.7-6.9 mmHg). No safety concerns were identified based on an assessment of ocular and cardiovascular parameters and a review of adverse events.

CONCLUSIONS

Brinzolamide 1%/timolol 05% is superior in IOP-lowering efficacy to either brinzolamide 1% or timolol 0.5%.

Cardiovascular and respiratory considerations with pharmacotherapy of glaucoma and ocular hypertension

Glaucoma and ocular hypertension are highly prevalent conditions in individuals over the age of 40 and are commonly seen together in patients with cardiovascular disease. Many of the antiglaucoma medications, when systemically absorbed, affect the sympathetic and parasympathetic nervous systems of patients and can cause cardiovascular toxicity. Such adverse effects are frequently associated with the long-term use of potentially toxic agents in elderly people, who are most prone to chronic eye disease. Moreover, patients may not associate their symptoms with the topical eye medications, and consequently may not report adverse drug effects. Drug-drug interactions can also occur when patients are taking medications for both cardiovascular disease and glaucoma. In this review, the systemic toxicity of these agents is reviewed, along with possible drug-drug interactions. Mention is made of other antiglaucoma medications used alone and in combination with topical beta-blockers. Identification of genetic loci-a bold new step toward glaucoma treatment-is mentioned briefly at the end of the article.

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.

Comparison of twice-daily and three-times-daily dosing of dorzolamide in ocular hypertension and primary open-angle glaucoma patients treated with latanoprost

INTRODUCTION

Clinically, dorzolamide (Trusopt(R); Merck & Co Inc, West Point, PA, USA) is often used twice daily (b.i.d.) or three times daily (t.i.d.) as adjunctive therapy with prostaglandins. Our purpose was to determine the effect of dorzolamide on intraocular pressure (IOP) when added to latanoprost (Xalatan(R); Pfizer Inc, New York, NY, USA) baseline treatment, and to evaluate potential efficacy differences between b.i.d. and t.i.d. dosing of dorzolamide.

METHODS

This was a prospective, randomised, two-period crossover trial in ocular hypertensive or primary open-angle glaucoma patients (29 eyes in 15 patients) with an IOP of > 20 mmHg on latanoprost baseline treatment. Patients were randomly assigned to b.i.d. (08.00 and 20.00) or t.i.d. (08.00, 16.00 and 20.00) dosing of dorzolamide, treated in both eyes for 4 weeks, washed out for 3 weeks, then switched to the opposite dosing frequency for 4 weeks. Diurnal IOP measurements (every 2 hours from 08.00 to 20.00) were performed at baseline and at the end of treatment periods.

RESULTS

The mean baseline IOP was 20.9+/-0.6 mmHg. After b.i.d. and t.i.d. dosing, the mean IOP was 17.7+/-0.6 mmHg (13.5% reduction) and 17.8+/-0.8 mmHg (16.5% reduction), respectively (both P<0.001 compared with baseline IOP). Diurnal IOP control was similar in the two groups, although mean IOP reduction was significantly lower at 18.00 on the t.i.d. regimen (4.7+/-3.3 mmHg) than with the b.i.d. regimen (2.3+/-2.7 mmHg, P=0.038). At other time points, no significant differences between the groups were observed.

CONCLUSION

Dorzolamide 2% added to latanoprost 0.005% baseline treatment caused a significant decrease in IOP. The b.i.d. versus t.i.d. dosing of dorzolamide did not significantly affect a change in IOP except at one afternoon time point.

Predictive value of the efficacy of glaucoma medications in regulatory trials: Phase I-III to post-marketing studies

PURPOSE

To determine the predictive value of early Phase trials (I-II) for the ocular hypotensive efficacy observed in Phases III and IV.

DESIGN

A review of published literature.

METHODS

This study evaluated 12 medicines in 65 articles in the literature with at least two phases available.

RESULTS

For medicines with Phase I results available (n=3), the average reduction in intraocular pressure (IOP) from untreated baseline was 16%, 26% for Phase II, 26% for Phase III, and 24% for Phase IV. For medicines with Phase II results available (n=6), the average reduction in IOP was 23%, 24% for Phase III, and 23% for Phase IV. For medicines with Phase III results available (n=11), the average reduction in IOP was 25% and 24% for Phase IV.

CONCLUSION

This study indicates that early phase trials usually approximated the results of later regulatory studies and post-commercialization trials.

Retrobulbar haemodynamic effects of the latanoprost/timolol and the dorzolamide/timolol fixed combinations in newly diagnosed glaucoma patients

The objective of this study was to compare the effect of the latanoprost/timolol fixed combination (LTFC) and the dorzolamide/timolol fixed combination (DTFC) on the retrobulbar haemodynamic and intraocular pressure (IOP) in patents with open-angle glaucoma (OAG). This was a prospective, examiner masked, randomised and crossover study. Participants were 32 consecutive subjects, who met the inclusion/exclusion criteria, with newly diagnosed OAG. Patients were randomised to either LTFC or DTFC for the first 1-month treatment phase after a 1-month washout period, without medical treatment, patients began with the opposite treatment for the second 1-month treatment period. Colour Doppler parameters in ophthalmic artery (OA) and posterior ciliary arteries (PCA), ocular perfusion pressure, IOP and systemic haemodynamics were assessed at each baseline and at the end of each treatment period. The main outcomes include peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistance index (RI) in OA and PCA. DTFC significantly increased EDV in OA from 7.55 (1.16) to 9.32 (1.22), p<0.0001, and in the PCA from 4.41 (0.70) to 5.36 (0.60), p<0.0001, and significantly decreased RI in OA from 0.775 (0.036) to 0.725 (0.032), p<0.0001, and in the PCA from 0.694 (0.045) to 0.634 (0.034). LTFC significantly decreased the EDV and significantly increased RI in PCA, p=0.0076 and p=0.0009, respectively. There were no statistical significant differences in the IOP lowering effect between both treatments. DTFC seems to have a beneficial vascular effect on retrobulbar vessels in OAG patients.

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.

Intraocular Pressure–Lowering Effect of Adding Dorzolamide or Latanoprost to Timolol

OBJECTIVE

To estimate the intraocular pressure (IOP)-lowering effect of 2% dorzolamide or 0.005% latanoprost when added to 0.5% timolol.

DESIGN

Meta-analysis of randomized clinical trials.

PARTICIPANTS

Seventeen articles reporting on 19 study arms with 5 possible treatment combinations and 4 study arms serving as controls.

METHODS

Articles written in English, German, French, or Dutch and published up to December 2004 were identified in Medline, Embase, the Cochrane Controlled Trials Register, and references from relevant articles. For the article to be considered, over 85% of the patients had to have primary open-angle glaucoma or ocular hypertension. The pooled 1- to 3-month additional IOP-lowering effect after a run-in phase on timolol was calculated by performing meta-analysis using the random effects model.

MAIN OUTCOME MEASURES

Absolute and relative changes in IOP after run-in on timolol for peak moment, trough moment, or mean diurnal curve.

RESULTS

The pooled change from baseline [mean (95% confidence interval)] for 0.5% timolol varied from -0.7 mmHg (-1.2 to -0.2, for the mean diurnal curve) to -2.0 mmHg (-1.3 to -2.7, at peak). Pooled changes for 2% dorzolamide in concomitant use with 0.5% timolol were -4.1 mmHg (-4.4 to -3.8) at trough and -4.9 mmHg (-5.3 to -4.5) at peak. The fixed 2% dorzolamide and 0.5% timolol combination resulted in a pooled change of -3.8 mmHg (-4.2 to -3.4) at trough and -4.9 mmHg (-5.3 to -4.5) at peak. The concomitant use of 0.005% latanoprost and 0.5% timolol gave a pooled change from baseline of -6.0 mmHg (-6.8 to -5.2) at the mean diurnal curve. The fixed combination of 0.005% latanoprost and 0.5% timolol resulted in a mean change of -3.0 mmHg (-3.8 to -2.2) at the mean diurnal curve.

CONCLUSION

In this meta-analysis of clinical trials, the addition of dorzolamide or latanoprost further lowers IOP in eyes on timolol. This result may not be generalizable because these trials may have included nonresponders to timolol.

Topical Drug Therapy in Glaucoma

Glaucoma is defined as a progressive optic neuropathy involving characteristic structural changes in the optic nerve head and corresponding visual field defects. Elevated intraocular pressure (IOP) is a major risk and causative factor for glaucomatous optic neuropathy. Although mechanisms other than elevated IOP may contribute to the underlying pathophysiology of glaucoma, reducing IOP remains the primary goal of therapy. Recent clinical studies have shown that decreasing the IOP can delay, or in some cases prevent progression of this chronic ocular disease. Over the past decade, several new medical therapies have become available for the treatment of glaucoma. In this article a review of topical glaucoma therapy is presented.

Comparison of the effects of topical administration of a fixed combination of dorzolamide-timolol to monotherapy with timolol or dorzolamide on IOP, pupil size, and heart rate in glaucomatous dogs

OBJECTIVE

To determine whether the combination multiple-dose dorzolamide-timolol administered topically has any greater effects on the reduction of intraocular pressure, pupil size, and heart rate in dogs with glaucoma than do either timolol or dorzolamide alone.

PROCEDURE

Applanation tonometry, pupil size, and heart rate measurements were made at 7 a.m., 1 p.m., and 7 p.m. daily of 12 laboratory Beagles with inherited primary open-angle glaucoma during each active phase of this study. Timolol 0.5% was administered first twice daily for 4 consecutive days. Dorzolamide 2.0% was administered next three times daily for 4 consecutive days. The fixed combination of the two (timolol 0.5% and dorzolamide 2.0%) was administered twice daily for 4 consecutive days during the final week of the study. Between administration of each drug, a withdrawal period of at least 10 days was instituted. Statistical comparisons between the effects of the three drugs were performed.

RESULTS

Intraocular pressure (IOP) was decreased with the administration of all three drugs: timolol alone, dorzolamide alone, and the combination of the two decreased IOP after 1 day of treatment 2.83 +/- 0.70 mmHg, 6.47 +/- 0.32 mmHg, and 6.56 +/- 0.37 mmHg, respectively. After 4 days of treatment, the IOP decreased even further: timolol alone, dorzolamide alone, and the combination of the two decreased IOP 3.75 +/- 0.88 mmHg, 7.50 +/- 0.29 mmHg, and 8.42 +/- 0.58 mmHg, respectively. Heart rate was significantly decreased with timolol (-11.9 +/- 2.0 bpm) and the combination preparation (-8.6 + 2.4 bpm), but not with dorzolamide (-3.7 +/- 1.8 bpm) alone. Pupil size was significantly decreased with timolol (-1.42 + 0.40 mm) and the combination preparation (-1.3 + 0.33 mm), but not with dorzolamide (0.97 +/- 0.36 mm) alone.

CONCLUSIONS

The combination dorzolamide-timolol appears to be more effective at reducing intraocular pressure in glaucomatous dogs than is either timolol or dorzolamide alone.

Evolving Paradigms in the Medical Treatment of Glaucoma

In the last 5 years, numerous novel ocular hypotensive agents have been introduced for the control of intraocular pressure (IOP). Clinicians now have more options than ever in medical therapy for the treatment of glaucoma and ocular hypertension. When selecting an ocular hypotensive medication for their patients, clinicians should consider not only the IOP-lowering efficacy of an agent but also the ability of the drug to achieve target levels of IOP that are low enough to stop the progression of glaucomatous damage. Other considerations should include how well the drug controls diurnal IOP, the likelihood of serious adverse events, the versatility of the medication for use as an adjunctive agent, as well as other potential attributes (e.g., neuroprotection).

Timolol/dorzolamide combination therapy as initial treatment for intraocular pressure over 30 mm Hg

PURPOSE

To determine the intraocular pressure (IOP)-lowering effect of a fixed timolol/dorzolamide combination (Cosopt) for patients with IOP over 30 mm Hg.

STUDY DESIGN

Prospective interventional case series.

METHODS

Eighteen patients being seen on the Wills Eye Hospital Glaucoma Service with at least one eye with an IOP > 30 mm Hg were recruited. None had used any glaucoma medications for at least 1 month. IOP was confirmed by diurnal testing. Cosopt was administered at 9 am and 9 pm. Trough IOP measurements were made at 9 am and peak IOP measurements at 11 am at baseline, 1 month, and 2 months. Pretreatment and posttreatment IOPs were compared using a paired-samples independent t test.

RESULTS

Mean pretreatment IOP was 37.5 +/- 1.0 mm Hg. Baseline posttreatment IOP was 18.4 +/- 0.5 mm Hg (P < 0.01). At 2 months, the mean trough IOP was 21.1 +/- 0.9 mm Hg and the peak, 17.6 +/- 0.6 mm Hg (each, P < 0.01, as compared with pretreatment baseline IOP). One patient did not respond to Cosopt; two had a clinically insufficient response and did not complete the study. Data from these patients were included in the analysis.

CONCLUSIONS

Over 80% of the eyes responded to Cosopt, with an average trough IOP reduction of 40% at 2 months.

Comparing the fixed combination dorzolamide-timolol (Cosopt) to concomitant administration of 2% dorzolamide (Trusopt) and 0.5% timolol -- a randomized controlled trial and a replacement study

PURPOSE

To compare the intraocular pressure (IOP) lowering effect of concomitant administration of 0.5% timolol and 2% dorzolamide and a fixed combination dorzolamide-timolol (Cosopt) To critically evaluate discrepancies between phase 3 clinical trials and prior replacement studies.

DESIGN

A prospective, randomized, controlled clinical trial and a prospective, non-randomized comparative replacement trial.

PARTICIPANTS/INTERVENTIONS

In a national multicentre trial, 131 patients were randomized to dorzolamide-timolol or a topical carbonic anhydrase inhibitor (CAI) and non-selective beta-blocker following a 1-month run-in using the separate components. Peak (maximal drug effect) and trough (minimal drug effect) IOPs were measured at baseline and 1 month after treatment. The replacement therapy study enrolled 404 consecutive glaucoma patients using a non-selective beta-blocker and dorzolamide and changed treatment to the fixed combination. Mean IOPs at the same time of day were compared before and 1 month after changeover.

MAIN OUTCOME MEASURE

The main outcome measure was IOP, comparing baseline and on-therapy measurements at study conclusion between the two arms of the randomized trial and before and after switching therapy in the replacement trial.

RESULTS

In the randomized trial, the mean baseline peak and trough IOPs were 18.4 and 21.0 mmHg in the group randomized to combination therapy and 17.6 and 19.8 mmHg in the dual drug group. After randomization and treatment for four weeks, the peak and trough IOPs were 17.6 and 19.5 mmHg in the combination group and 17.3 and 19.0 mmHg in the concomitant group. The percentage change in IOP was -3.2% at peak and -6.5% at trough for the combination and -0.3 and -3.2% for the concomitant group. These differences did not show statistical significance. In the replacement study, mean baseline IOP was 19.4 mmHg. Four weeks after initiation of treatment on the fixed combination, a significant additional IOP reduction of 1.7 mmHg (-8.8%) was observed (P < 0.0001). Overall, 81% of eyes exhibited equal or lower IOP on the fixed combination compared with concomitant therapy.

CONCLUSION

The results of the randomized trial indicate that the fixed combination dorzolamide-timolol (Cosopt) was as effective as its components in controlling IOP, confirming results seen in phase 3 clinical trials. However, in the replacement study, utilization of the combination drug offered a statistically significant additional IOP reduction (P < 0.0001), which duplicates results from previous replacement studies.

Comparison of latanoprost with fixed-combination dorzolamide and timolol in adult patients with elevated intraocular pressure: an eight-week, randomized, open-label, parallel-group, multicenter study in Latin America

BACKGROUND

The newer ocular hypotensive agents available to treat glaucoma and ocular hypertension (OHT) include latanoprost, a prostaglandin F(2alpha) analogue, and the fixed combination of dorzolamide hydrochloride, a carbonic anhydrase inhibitor, and timolol maleate, a beta-blocker.

OBJECTIVE

The aim of this study was to compare the efficacy and tolerability of latanoprost with that of the fixed combination of dorzolamide and timolol over 8 weeks.

METHODS

This interventional, 8-week, randomized, open-label, parallel-group study was conducted at 18 centers in 6 Latin American countries. Patients with unilateral or bilateral primary open-angle, pigmentary, or exfoliative glaucoma or OHT were randomized to receive latanoprost, 1 drop in the affected eye QD (evening), or fixed-combination dorzolamide/timolol, 1 drop in the affected eye BID (morning and evening). Medications were self-administered, 1 drop per affected eye. At baseline and week 8, intraocular pressure (IOP) was measured 3 times each at 8:30 am, 10:00 am, 2:00 pm, and 5:00 pm and after the water-drinking test, which estimates the IOP peak of diurnal tension curve, performed following the 5:00 pm IOP assessment. The primary efficacy outcome was change in diurnal IOP (the mean of IOP measurements) from baseline to week 8. Adverse effect (AE) data were recorded at each visit.

RESULTS

A total of 229 patients were randomized (latanoprost, n = 112; dorzolamide/timolol, n = 117). Mean baseline diurnal IOP values were similar between the 2 groups. Mean (SD) diurnal IOP reductions at week 8 before the water-drinking test were 6.9 (3.0) mm Hg for the latanoprost group and 6.4 (3.2) mm Hg for the dorzolamide/timolol group. Mean IOP values were similar at all time points except at 5:00 pm, when levels were significantly lower in latanoprost-treated patients (P = 0.025). After the water-drinking test, the increase in IOP values was similar between groups at baseline but lower in latanoprost-treated patients at week 8 (adjusted difference, 1.08 mm Hg; P = 0.012). Fewer patients treated with latanoprost reported ocular or systemic AEs (P = 0.025 and P < 0.001, respectively).

CONCLUSIONS

In this study of patients with unilateral or bilateral primary open-angle, pigmentary, or exfoliative glaucoma or OHT IOP reductions generally were similar between treatment groups, except at 5:00 pm, when the mean IOP level was significantly lower in latanoprost-treated patients. Latanoprost was better tolerated than fixed-combination dorzolamide and timolol.