A comparison of the long-term effects of dorzolamide 2% and brinzolamide 1%, each added to timolol 0.5%, on retrobulbar hemodynamics and intraocular pressure in open-angle glaucoma patients

Insulin restores retinal ganglion cell functional connectivity and promotes visual recovery in glaucoma

Dendrite pathology and synaptic loss result in neural circuit dysfunction, a common feature of neurodegenerative diseases. There is a lack of strategies that target dendritic and synaptic regeneration to promote neurorecovery. We show that daily human recombinant insulin eye drops stimulate retinal ganglion cell (RGC) dendrite and synapse regeneration during ocular hypertension, a risk factor to develop glaucoma. We demonstrate that the ribosomal protein p70S6 kinase (S6K) is essential for insulin-dependent dendritic regrowth. Furthermore, S6K phosphorylation of the stress-activated protein kinase-interacting protein 1 (SIN1), a link between the mammalian target of rapamycin complexes 1 and 2 (mTORC1/2), is required for insulin-induced dendritic regeneration. Using two-photon microscopy live retinal imaging, we show that insulin rescues single-RGC light-evoked calcium (Ca2+) dynamics. We further demonstrate that insulin enhances neuronal survival and retina-brain connectivity leading to improved optomotor reflex-elicited behaviors. Our data support that insulin is a compelling pro-regenerative strategy with potential clinical implications for the treatment and management of glaucoma.

Topical carbonic anhydrase inhibitors and glaucoma in 2021: where do we stand?

Carbonic anhydrase inhibitors (CAIs) have been used for many decades in the treatment of glaucoma. Systemic CAIs were an early treatment option to lower intraocular pressure by reducing aqueous humour production; however, frequent side effects including polyuria and paresthesia contributed to the eventual development of topical CAIs. As topical drug development evolved over time, prostaglandin analogues and beta-blockers have become the gold standard of glaucoma therapies. Although prescribed less often than other classes of topical glaucoma therapies, topical CAIs continue to be used in combination therapies with beta-blockers and alpha agonists. Topical CAIs have also been demonstrated to alter biomarkers of ocular haemodynamics, which have relevance in glaucoma. The purpose of this review is to review and summarise the current state of topical CAI prescribing trends, known efficacy and suggested mechanisms and potential influence on ocular haemodynamics for the future of glaucoma management.

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

Efficacy and Safety of Brinzolamide as Add-On to Prostaglandin Analogues or β-Blocker for Glaucoma and Ocular Hypertension: A Systematic Review and Meta-Analysis

Background: Brinzolamide as a carbonic anhydrase inhibitor could be combined with other intraocular pressure (IOP) lowering drugs for glaucoma and ocular hypertension (OHT), but the efficacy was controversial. So, this study was used to assess the efficacy and safety of brinzolamide as add-on to prostaglandin analogues (PGAs) or β-blocker in treating patients with glaucoma or OHT who fail to adequately control IOP.

Methods: We searched PubMed, Embase, MEDLINE, Cochrane Library, and clinicaltrials.gov from inception to October 4, 2018. Randomized controlled trials of brinzolamide as add-on to PGAs or β-blocker for glaucoma and OHT were included. Meta-analysis was conducted by RevMan 5.3 software.

Results: A total of 26 trials including 5,583 patients were analyzed. Brinzolamide produced absolute reductions of IOP as an adjunctive therapy for patients with glaucoma or OHT. Brinzolamide and timolol were not significantly different in lowering IOP as add-on to PGAs (9 am: P = 0.07; 12 am: P = 0.66; 4 pm: P = 0.66). Likewise, brinzolamide was as effective as dorzolamide in depressing IOP (9 am: P = 0.59; 12 am: P = 0.94; 4 pm: P = 0.95). For the mean diurnal IOP at the end of treatment duration, there were no statistical differences in above comparisons (P > 0.05). Compared with brimonidine (b.i.d.), there was a significant reduction of IOP in brinzolamide (b.i.d.) at 9 am (P < 0.0001); however, the difference was cloudy in thrice daily subgroup (P = 0.44); at 12 am, brinzolamide (b.i.d.) was similar to brimonidine (b.i.d.) in IOP-lowering effect (P = 0.23), whereas brimonidine (t.i.d.) led to a greater effect than brinzolamide (t.i.d.) (P = 0.02). At 4 pm, brinzolamide (b.i.d.) was superior IOP-lowering effect compared with brimonidine (b.i.d.) (P = 0.0003); conversely, the effect in brinzolamide (t.i.d.) was lower than brimonidine (t.i.d.) (P < 0.0001). For the mean diurnal IOP, brinzolamide was lower in twice daily subgroup (P < 0.00001); brimonidine was lower in thrice daily subgroup (P < 0.00001). With regard to the safety, brinzolamide and dorzolamide had a higher incidence of taste abnormality; moreover, brinzolamide resulted in more frequent blurred vision; dorzolamide resulted in more frequent ocular discomfort and eye pain. Timolol resulted in more frequent blurred vision and less conjunctival hyperemia. Brimonidine resulted in more frequent ocular hyperemia. As to other adverse events (AEs) (conjunctivitis, eye pruritus, foreign body sensation in eyes, and treatment-related AEs), brinzolamide was similar to other three active comparators.

Conclusions: Brinzolamide, as add-on to PGAs or β-blocker, significantly decreased IOP of patients with refractory glaucoma or OHT and the AEs were tolerable.

Effects of brinzolamide on rabbit ocular blood flow in vivo and ex vivo

AIM

To investigate if significant improvement of optic disc blood flow (ODBF) occurs after instillation of brinzolamide onto rabbit eyes.

METHODS

Testing of bilateral intraocular pressure (IOP) and left ODBF in 10 male rabbits took place every 3h over a 24h period. Brinzolamide (1% ophthalmic solution, two drops at 9:00 and 21:00) was administered to the left eye. ODBF, assessed using laser speckle flowgraphy, was determined as the mean blur rate (MBR). Furthermore, the effect of brinzolamide on isolated rabbit ciliary arteries using isometric tension recording system was performed.

RESULTS

After brinzolamide instillation, IOP was significantly decreased in the left eye. MBR-vessel was greater at 18:00 and 21:00 (P<0.05) than in the controls. MBR-tissue and MBR-average were greater at 18:00 (P<0.05) than in the controls. For isolated arteries pre-contracted with a high-K solution, brinzolamide induced concentration-dependent relaxation, reaching 46.1%±9% (n=21) at 1 mmol/L. In Ca²⁺-free solutions, incubation with brinzolamide suppressed 1 µmol/L histamine-induced contractions (P<0.05).

CONCLUSION

Brinzolamide decreases IOP and increases ocular blood flow. The direct vasodilatory effect of brizolamide is mediated by suppression of Ca²⁺ release from intracellular calcium stores.

Management of glaucoma as a neurodegenerative disease

Glaucoma is a neurodegenerative disease with an estimated prevalence of 60 million people, and the most common cause of irreversible blindness worldwide. The mainstay of treatment has been aimed at lowering intraocular pressure, currently the only modifiable risk factor. Unfortunately, despite adequate pressure control, many patients go on to suffer irreversible visual loss. We first briefly examine currently established intraocular pressure lowering-treatments, with a discussion of their roles in neuroprotection as demonstrated by both animal and clinical studies. The review then examines currently available intraocular pressure independent agents that have shown promise for possessing neuroprotective effects in the management of glaucoma. Finally, we explore potential future treatments such as immune-modulation, stem cell therapy and neural regeneration as they may provide further protection against the neurodegenerative processes involved in glaucomatous optic neuropathy.

Management of glaucoma in pregnancy: risks or choices, a dilemma?

The treatment of glaucoma in and around pregnancy offers the unique challenge of balancing the risk of vision loss to the mother as against the potential harm to the fetus or newborn. Most anti-glaucoma drugs (i.e. beta-blockers, prostaglandin analogues, carbonic anhydrase inhibitors topical and systemic, cholinergics, anticholinesterases, and apraclonidine) are considered category C agents and ophthalmologists are usually limited to treating patients with the category B drugs of brimonidine and dipivefrin. Brimonidine is generally the preferred first-line drug in the first, second and early third trimester. Late in the third trimester, brimonidine should be discontinued because it can induce central nervous system depression in newborns wherein topical carbonic anhydrase inhibitors may be the optimal choice. Glaucoma surgery can be performed with caution in second and third trimester if the patients have a strong indication for the procedure. However, anesthetics, sedative agents, and antimetabolites still have potential risk for the fetus. Argon laser trabeculoplasty (ALT) or selective laser trabeculoplasty (SLT) is an alternative treatment that can be performed in all trimesters. Carbonic anhydrase inhibitors and β-blockers are certified by the American Academy of Pediatrics for use during nursing. However, low doses of these medications should be considered when used in the breast feeding period. Optimum treatment for glaucoma in pregnancy must not be withheld so as to prevent any further deterioration in progressive vision loss and quality of life.

Effects of dorzolamide/timolol fixed combination on retrobulbar hemodynamics in pseudoexfoliative glaucoma

In our study we aimed to evaluate the short-term effects of dorzolamide/timolol on ocular perfusion pressure and retrobulbar blood flow in patients with pseudoexfoliative glaucoma (PXG). This prospective observational cross-sectional study enrolled 22 eyes of 22 newly-diagnosed patients with PXG in a single center. All of the patients received a fixed combination of dorzolamide/timolol. Besides routine ophthalmologic examination, the retrobulbar hemodynamic parameters in the ophthalmic artery, central retinal artery, and short posterior ciliary arteries were measured in all participants at baseline and the 3(rd) month using color Doppler imaging. The mean intraocular pressure (IOP) was 22.3 ± 2.1 mmHg at baseline and reduced to 17.4 ± 2.3 mmHg at the 3(rd) month (p < 0.05). None of the retrobulbar parameters, except peak systolic velocity and resistive index in temporal short posterior ciliary arteries, changed significantly on therapy with dorzolamide/timolol fixed combination when the results were analyzed at Month 3. The drug significantly decreased the peak systolic velocity (p = 0.044) and reduced the resistive index in 0.04 units, 95% confidence interval 0.03-0.05, (p < 0.001) in the temporal short posterior ciliary arteries. This study reports that the retrobulbar hemodynamics might be affected less than expected by dorzolamide/timolol fixed combination in patients with PXG although the reduction of IOP was statistically significant.

Ophthalmic artery blood flow parameters in pseudoexfoliation glaucoma

PURPOSE

To investigate orbital flow parameters of ophthalmic artery (OA) in patients with pseudoexfoliation glaucoma (XFG) by ultrasonography.

METHODS

This case-control study included 38 patients with XFG and 32 healthy control subjects. Color Doppler imaging was performed to evaluate orbital flow parameters of OA. Receiver operating characteristic analyses were performed to define the best cutoff value.

RESULTS

In the XFG group, decreased peak systolic velocity (p = 0.114), end diastolic velocity (p = 0.002), and increased resistivity index (RI) (p&lt;0.001) at OA compared to healthy controls were observed. A cutoff value 0.72 for OA RI was found to have a sensitivity of 66% and specificity of 94%.

CONCLUSIONS

The results support the findings of increased vascular resistance in OA XFG. High sensitivity and specificity obtained for OA RI may be useful in evaluation of future therapeutic vascular agents.

Safety and efficacy of a fixed versus unfixed brinzolamide/timolol combination in Japanese patients with open-angle glaucoma or ocular hypertension

Background

The purpose of this study was to assess the safety and efficacy of fixed-combination brinzolamide 1%/timolol 0.5% (BRINZ/TIM-FC) compared with concomitant brinzolamide 1% and timolol 0.5% (BRINZ + TIM) in Japanese patients with open-angle glaucoma (primary open-angle, exfoliation, pigmentary) or ocular hypertension.

Methods

This randomized, double-masked, multicenter, parallel-group, positive-control, Phase III study was conducted in Japan and included patients aged ≥20 years. Baseline intraocular pressure was assessed after 4 weeks of treatment with timolol 0.5%. Patients were randomized to twice-daily BRINZ/TIM-FC or BRINZ + TIM for 8 weeks (treatment phase). The primary endpoint was mean intraocular pressure reduction from baseline to week 8 at 11 am, at which time noninferiority of BRINZ/TIM-FC versus BRINZ + TIM was evaluated. Data were analyzed using repeated-measures analysis of covariance and t-tests. Adverse events and ophthalmic/physiologic variables were assessed.

Results

In total, 319 patients of mean age 64±12 years were enrolled in the treatment phase. BRINZ/TIM-FC and BRINZ + TIM were associated with reductions in mean intraocular pressure from baseline throughout the study (ranges −2.5 to −3.4 mmHg and −2.7 to −3.3 mmHg, respectively). Mean between-group differences in intraocular pressure reduction ranged from 0 to −0.3 mmHg; the upper limit of the 97.5% confidence interval for week 8 at 11 am was <1.1 mmHg, indicating noninferiority of BRINZ/TIM-FC. Treatment-related adverse events were observed in 3% and 12% of patients receiving BRINZ/TIM-FC and BRINZ + TIM, respectively. No substantial changes in other safety parameters were reported.

Conclusion

Twice-daily BRINZ/TIM-FC reduced intraocular pressure by levels similar to concomitant BRINZ + TIM in Japanese patients with open-angle glaucoma or ocular hypertension and was noninferior to BRINZ + TIM. Both treatments were well tolerated.

Phase III safety and efficacy study of long-term brinzolamide/timolol fixed combination in Japanese patients with open-angle glaucoma or ocular hypertension

BACKGROUND

The purpose of this study was to evaluate the safety and efficacy of a long-term, twice-daily brinzolamide 1%/timolol 0.5% fixed combination ophthalmic suspension (BRINZ/TIM-FC) in Japanese patients with open-angle glaucoma (primary open-angle, normal-tension, exfoliation, or pigmentary) or ocular hypertension.

METHODS

This was a prospective, nonrandomized, multicenter, open-label, Phase III study of Japanese patients aged ≥20 years with diagnoses of open-angle glaucoma or ocular hypertension. Patients were treated with topical BRINZ/TIM-FC twice daily for 52 weeks. The primary endpoint was mean reduction from baseline in intraocular pressure. Data were analyzed using repeated-measures analysis of variance and t-tests. Adverse events and ophthalmic, physiologic, and laboratory parameters were measured throughout the study as safety endpoints. A total of 126 patients (mean ± SD age, 63±12 years) were enrolled, and 125 received BRINZ/TIM-FC.

RESULTS

Mean intraocular pressure was significantly reduced from baseline at weeks 4 through 52, with changes ranging from -4.1 mmHg to -5.7 mmHg (P<0.0001, all time points). Adverse events related to BRINZ/TIM-FC treatment were observed in 22% of patients. No substantial changes from baseline were observed in ophthalmic, physiologic, or laboratory variables.

CONCLUSION

Long-term, twice-daily BRINZ/TIM-FC therapy produced and maintained significant intraocular pressure reductions and was generally well tolerated in Japanese patients with open-angle glaucoma or ocular hypertension.

Secondary neuroprotective effects of hypotensive drugs and potential mechanisms of action

Primary open-angle glaucoma, a long-term degenerative ocular neuropathy, remains a significant cause of vision impairment worldwide. While many risk factors have been correlated with increased risk for primary open-angle glaucoma, intraocular pressure (IOP) remains the only modifiable risk factor and primary therapeutic target. Pharmacologic therapies are administered topically; these include α(2)-agonists, β-antagonists, prostaglandin analogs and carbonic anhydrase inhibitors. Some of these topical medications exhibit secondary neuroprotective effects independent of their effect on IOP. This review covers the possible mechanisms of neuroprotection stimulated by drugs currently marketed for the lowering of IOP, based on known literature. While the neuroprotective properties of many glaucoma pharmaceuticals are promising from an experimental standpoint, key challenges for the development of new clinical practices include unknown systemic side effects, limited methods of drug delivery to the retina and optic nerve, and development of extended-release formulations.

Crystallins are regulated biomarkers for monitoring topical therapy of glaucomatous optic neuropathy

Optic nerve atrophy caused by abnormal intraocular pressure (IOP) remains the most common cause of irreversible loss of vision worldwide. The aim of this study was to determine whether topically applied IOP-lowering eye drugs affect retinal ganglion cells (RGCs) and retinal metabolism in a rat model of optic neuropathy. IOP was elevated through cauterization of episcleral veins, and then lowered either by the daily topical application of timolol, timolol/travoprost, timolol/dorzolamide, or timolol/brimonidine, or surgically with sectorial iridectomy. RGCs were retrogradely labeled 4 days prior to enucleation, and counted. Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), matrix-assisted laser desorption ionization mass spectrometry, Western blotting, and immunohistochemistry allowed the identification of IOP-dependent proteomic changes. Genomic changes were scrutinized using microarrays and qRT-PCR. The significant increase in IOP induced by episcleral vein cauterization that persisted until 8 weeks of follow-up in control animals (p<0.05) was effectively lowered by the eye drops (p<0.05). As anticipated, the number of RGCs decreased significantly following 8 weeks of elevated IOP (p<0.05), while treatment with combination compounds markedly improved RGC survival (p<0.05). 2D-PAGE and Western blot analyses revealed an IOP-dependent expression of crystallin cry-βb2. Microarray and qRT-PCR analyses verified the results at the mRNA level. IHC demonstrated that crystallins were expressed mainly in the ganglion cell layer. The data suggest that IOP and either topically applied antiglaucomatous drugs influence crystallin expression within the retina. Neuronal crystallins are thus suitable biomarkers for monitoring the progression of neuropathy and evaluating any neuroprotective effects.

Current primary open-angle glaucoma treatments and future directions

Primary open-angle glaucoma (POAG) is a leading cause of blindness with no known cure. Management of the disease focuses on lowering intraocular pressure (IOP) with current classes of drugs like prostaglandin analogs, beta-blockers, alpha-agonists, and carbonic anhydrase inhibitors. These treatments have not helped all patients. Some patients continue to experience deterioration in the optic nerve even though their IOPs are within the normal range. New views have surfaced about other pathophysiological processes (such as oxidative stress, vascular dysfunction, and retinal cell apoptosis) being involved in POAG progression, and adjunctive treatments with drugs like memantine, bis(7)-tacrine, nimodipine, and mirtogenol are advocated. This review examines the current and proposed treatments for POAG. Some of the proposed drugs (bis(7)-tacrine, nimodipine, vitamin E, and others) have shown good promise, mostly as monotherapy in various clinical trials. It is recommended that both the current and proposed drugs be put through further robust trials in concurrent administration and evaluated.

Dorzolamide-induced relaxation of intraocular porcine ciliary arteries in vitro depends on nitric oxide and the vascular endothelium

PURPOSE

Carbonic anhydrase inhibitors (CAIs) are used to reduce aqueous production in glaucoma, which includes a direct effect on the ciliary body. However, CAIs also affect ciliary blood flow, but the mechanisms of action of CAIs on the tone of intraocular ciliary arteries supplying the ciliary body have not been studied in detail.

MATERIALS AND METHODS

The intraocular part of porcine ciliary arteries was isolated and mounted in a wire myograph system for isometric tension recordings. After contraction with the thromboxane analogue U46619, the vasorelaxing effect of the CAIs acetazolamide, brinzolamide and dorzolamide was studied. Subsequently, the involvement of the carbonic anhydrase reaction and nitric oxide (NO) in dorzolamide-induced vasorelaxation was characterized.

RESULTS

All CAIs induced relaxation of contracted ciliary arteries, but the effect of dorzolamide was most pronounced. Dorzolamide-induced relaxation was unaffected by changes in pH and CO(2), and by removal of substrates to the carbonic anhydrase enzyme, but was abolished after inhibition of NO synthase and guanylyl cyclase and after removal of the vascular endothelium.

CONCLUSIONS

Dorzolamide-induced vasorelaxation of ciliary arteries is independent of changes in the substances involved in the carbonic anhydrase reaction, but depends on NO and the vascular endothelium. The mechanism of action of dorzolamide in ocular disease may involve an effect on vascular tone mediated by NO.

Regulation of retinal proteome by topical antiglaucomatous eye drops in an inherited glaucoma rat model

Examination of the response of the retinal proteome to elevated intraocular pressure (IOP) and to the pharmacological normalization of IOP is crucial, in order to develop drugs with neuroptorective potential. We used a hereditary rat model of ocular hypertension to lower IOP with travaprost and dorzolamide applied topically on the eye surface, and examine changes of the retinal proteome. Our data demonstrate that elevated IOP causes alterations in the retinal protein profile, in particular in high-mobility-group-protein B1 (HMGB1), calmodulin, heat-shock-protein (HSP) 70 and carbonic anhydrase II expression. The changes of the retinal proteome by dorzolamide or travoprost are different and independent of the IOP lowering effect. This fact suggests that the eye drops exert a direct IOP-independent effect on retinal metabolism. Further investigations are required to elucidate the potential neuroprotective mechanisms signaled through changes of HMGB1, calmodulin, HSP70 and carbonic anhydrase II expression in glaucoma. The data may facilitate development of eye drops that exert neuroprotection through direct pharmacological effect.

The effects of a fixed combination of 0.5% timolol and 1% dorzolamide on optic nerve head blood circulation

PURPOSE

The purpose of the present study is to evaluate the effects of a fixed combination of 0.5% timolol maleate (TM) and 1% dorzolamide hydrochloride (DZ) (FCTD(1%)) on optic nerve head (ONH) blood circulation.

SUBJECTS AND METHODS

A drop of 0.5% TM, 1% DZ, or FCTD(1%) was topically administered to the right eyes of 15 healthy Japanese subjects, and a drop of saline was likewise administrated to their left eyes. Systemic blood pressure, heart rates (HRs), intraocular pressures (IOPs), ocular perfusion pressures, and blood circulation by a laser speckle flowgraphy at the ONH were measured before administration, and again at 1.5 and 6 h afterward.

RESULTS

FCTD(1%) caused a significant increase in ONH blood circulation 6 h after the administration, while 0.5% TM and 1% DZ had no significant effect. The IOPs were significantly decreased in 0.5% TM (P<0.01) and FCTD(1%) (P<0.05) when compared with the saline-treated eyes at 1.5 and 6 h after administration, while 1% DZ did not show a statistically significant decrease. There were no significant changes in other systemic parameters except for a significant transient decrease in the HRs observed in 0.5% TM (P<0.01) when compared with the baseline at 1.5 h after the administration.

CONCLUSION

Our current results suggest that FCTD(1%) caused a significant increase in ocular blood circulation on the ONH in healthy Japanese subjects, presumably by a synergistic effect of 0.5% TM and 1% DZ, although neither 0.5% TM nor 1% DZ on their own had a significant effect.

Ocular pharmacokinetics of dorzolamide and brinzolamide after single and multiple topical dosing: implications for effects on ocular blood flow

Ophthalmic carbonic anhydrase inhibitors have been shown to improve retinal and optic nerve blood flow. However, the relative tissue distributions of commercially available carbonic anhydrase inhibitors to the optic nerve are not known. The objective of this study was to compare the ocular pharmacokinetics and tissue distribution profiles of dorzolamide and brinzolamide after single and multiple topical applications. Pigmented rabbits were treated with single or multiple topical administrations of 30 μl of Trusopt (dorzolamide hydrochloride ophthalmic solution, 2%) to one eye and 30 μl of Azopt (brinzolamide ophthalmic suspension, 1%) to the other eye. Rabbits were euthanized at 10 predetermined time intervals over a period of 24 h, and ocular tissues and plasma samples were collected. For multiple dosing, rabbits were dosed twice per day with an 8-h interval between two doses, groups of rabbits were euthanized at 7, 14, and 21 days at 1 h after the last dose, and ocular tissues and plasma samples were collected. Drug levels in tissue samples were measured using liquid chromatography/tandem mass spectrometry. Pharmacokinetic parameters (C(max), T(max), and AUC(0-24)) were estimated by noncompartmental analysis. After a single dose, dorzolamide delivery (AUC(0-24)) to the aqueous humor, anterior sclera, posterior sclera, anterior retina, posterior retina, anterior vitreous, and optic nerve was 2-, 7-, 2.6-, 1.4-, 1.9-, 1.2-, and 9-fold higher than those of brinzolamide. C(max) was 2- to 5-fold higher for dorzolamide than that of brinzolamide in all of the ocular tissue. After multiple dosing, dorzolamide levels in the aqueous humor, sclera, retina, vitreous humor, and optic nerve were higher than those of brinzolamide, but statistical significance was achieved only with aqueous humor, vitreous humor, and optic nerve. Dorzolamide levels in the aqueous humor, anterior vitreous, posterior vitreous, and optic nerve were 1.4- to 3.2-, 2.4- to 2.7-, 2.2- to 4.5-, and 2.4- to 5.2-fold higher than those of brinzolamide. Upon multiple dosing, both drugs accumulated in all of the tissues except the conjunctiva, where the drug levels were lower than those observed with single dosing. No significant differences were found in the AUC values of these two drugs in the cornea and conjunctiva after single and multiple dosing. Drug levels were significantly higher in anterior regions than posterior regions in the sclera, retina, and vitreous for both drugs.

[Comparative study of the pressure lowering efficacy and variations in the ocular pulse amplitude between fixed combinations of dorzolamide/timolol and brinzolamide/timolol]

OBJECTIVE

To determine possible differences in the intraocular pressure (IOP) and ocular pulse amplitude (OPA) lowering capacity of the fixed drug combinations dorzolamide/timolol and brinzolamide/timolol.

METHODS

In this cross-sectional study, one of the eyes of 25 healthy subjects was randomly assigned to treatment with dorzolamide/timolol and the other eye with brinzolamide/timolol. After instilling the drops, possible adverse effects (e.g., blurred vision, itching) were assessed in each eye. This assessment was repeated 30 minutes later. IOP and OPA were determined In each eye by dynamic contour tonometry at baseline and two hours following treatment.

RESULTS

Both fixed drug combinations significantly reduced IOP and OPA with no differences detected between treatment groups. Among the adverse effects recorded, itching was significantly greater in the first assessment in the eyes treated with dorzolamide/timolol (P = .011). This difference was no longer apparent in the second assessment.

CONCLUSIONS

Both fixed combinations were similarly effective in reducing intraocular pressure and ocular pulse amplitude. Adverse effects related to both treatments were mild and well-tolerated, though itching occurred most frequently in the eyes treated with dorzolamide/timolol.

Comparison of the effects of dorzolamide/timolol and latanoprost/timolol fixed combinations upon intraocular pressure and progression of visual field damage in primary open-angle glaucoma

OBJECTIVE

To report the long-term effect of the dorzolamide/timolol (DTFC) and latanoprost/timolol (LTFC) fixed combinations on intraocular pressure (IOP) and visual field defects over time in naïve primary open-angle glaucoma (POAG) patients.

STUDY DESIGN AND METHODS

Prospective, 4-year, open-label, interventional study.

SETTING

high-volume outpatient clinic.

PATIENTS

178 patients were assigned to receive medical treatment with either DTFC or LTFC.

INTERVENTION

over 4 years, tri-monthly IOP and yearly visual field assessment (Octopus 101, Program G2). outcomes: effect of treatment on IOP, visual field indices mean defect (MD), and visual field indices variance loss (VL) over time.

RESULTS

DTFC and LTFC significantly (p < or = 0.001) reduced mean IOP over time (from 22.6 +/- 3.0 to 13.8 +/- 1.9 mmHg and from 22.3 +/- 4.0 to 14.7 +/- 1.9 mmHg, respectively). In all, 56 patients (70.9%) and 14 (17.9%) showed a significant MD improvement in the DTFC- and LTFC-treated groups, respectively, p = 0.0001. DTFC progressively and significantly decreased mean VL (from 30.21 +/- 23.88 to 8.11 +/- 8.50 dB). Mean sensitivity slopes during follow-up were 1.14 dB/year and -0.34 dB/year for DTFC and LTFC treatment groups, respectively; p = 0.028.

CONCLUSION

Both treatments significantly reduced IOP as compared with baseline. Additionally, treatment with dorzolamide/timolol fixed combination seem to be effective in preventing glaucomatous visual field progression. This study has some limitations that should be noted, among them its open-label design.

Topical carbonic anhydrase inhibitors and visual function in glaucoma and ocular hypertension

BACKGROUND

Dorzolamide and brinzolamide are topical carbonic anhydrase inhibitors (CAI) indicated for patients with glaucoma and ocular hypertension.

SCOPE

An evidence-based review of clinical trials of dorzolamide and brinzolamide was undertaken to determine an effect of these medications on visual function (primarily visual field) in open-angle glaucoma and ocular hypertension. Using the keywords 'dorzolamide' and 'brinzolamide', all articles describing trials of these medications reporting on visual acuity, contrast sensitivity and visual field from September 1966 to July 2009 were found in MEDLINE and EMBASE databases. No information from other sources was included in this review.

FINDINGS

A relatively modest number of trials was identified, where impact of therapy on one or more of the visual function modes was reported. In the studies of less than 1 year duration (3 days to 1 year, 23 studies) in all but three studies treatment with topical CAIs did not influence visual function, in two studies with dorzolamide some improvement in the contrast sensitivity was observed and in one open-label retrospective no-control-group study with dorzolamide visual field indices improved significantly. A different picture was seen in long-term studies, which were designed and powered to detect changes in visual field. One large study (European Glaucoma Prevention Study) with dorzolamide versus placebo failed to detect significant protective effect of the drug on glaucoma occurrence in ocular hypertensives. Several interesting aspects of this study are discussed in detail. The other two long-term studies reported on the superiority of adding dorzolamide over timolol therapy alone, and the superiority of the combination of dorzolamide and timolol over brinzolamide and timolol in terms of improving ocular blood flow (retrobulbar Color Doppler Imaging--CDI parameters) as well as in terms of visual field preservation in glaucoma patients over 4 to 5 years.

CONCLUSION

For the first time one study could demonstrate that an improvement in ocular blood flow in the long run results in preservation of visual field in glaucoma patients. Dorzolamide, combined with the beta-blocker timolol, seems to be superior in this regard to brinzolamide plus timolol.

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.

Role of fixed-combination brinzolamide 1%/timolol 0.5% in the treatment of elevated intraocular pressure in open-angle glaucoma and ocular hypertension

Brinzolamide 1%/timolol 0.5% is a new fixed-combination for the treatment of open-angle glaucoma or ocular hypertension. Brinzolamide/timolol has a favorable safety profile, with an incidence of ocular burning and stinging <5%. Published data show that brinzolamide 1%/timolol 0.5% and dorzolamide 2%/timolol 0.5% have similar efficacies for lowering intraocular pressure (IOP). There is some evidence that brinzolamide/timolol may be more comfortable. Although patients receiving brinzolamide/timolol may experience more blurred vision on instillation, some data show a preference for brinzolamide/timolol over dorzolamide/timolol. Although available data to assess the role of brinzolamide/timolol in daily clinical practice are still limited, these first results suggest the agent to be a reasonable alternative for patients who do not reach target IOP with monotherapy.