Dose response and duration of action of dorzolamide, a topical carbonic anhydrase inhibitor

Chemical Insights into Topical Agents in Intraocular Pressure Management: From Glaucoma Etiopathology to Therapeutic Approaches

Glaucoma encompasses a group of optic neuropathies characterized by complex and often elusive etiopathology, involvihttng neurodegeneration of the optic nerve in conjunction with abnormal intraocular pressure (IOP). Currently, there is no cure for glaucoma, and treatment strategies primarily aim to halt disease progression by managing IOP. This review delves into the etiopathology, diagnostic methods, and treatment approaches for glaucoma, with a special focus on IOP management. We discuss a range of active pharmaceutical ingredients used in glaucoma therapy, emphasizing their chemical structure, pharmacological action, therapeutic effectiveness, and safety/tolerability profiles. Notably, most of these therapeutic agents are administered as topical formulations, a critical aspect considering patient compliance and drug delivery efficiency. The classes of glaucoma therapeutics covered in this review include prostaglandin analogs, beta blockers, alpha agonists, carbonic anhydrase inhibitors, Rho kinase inhibitors, and miotic (cholinergic) agents. This comprehensive overview highlights the importance of topical administration in glaucoma treatment, offering insights into the current state and future directions of pharmacological management in glaucoma.

Stable Gastric Pentadecapeptide BPC 157-Possible Novel Therapy of Glaucoma and Other Ocular Conditions

Recently, stable gastric pentadecapeptide BPC 157 therapy by activation of collateral pathways counteracted various occlusion/occlusion-like syndromes, vascular, and multiorgan failure, and blood pressure disturbances in rats with permanent major vessel occlusion and similar procedures disabling endothelium function. Thereby, we revealed BPC 157 cytoprotective therapy with strong vascular rescuing capabilities in glaucoma therapy. With these capabilities, BPC 157 therapy can recover glaucomatous rats, normalize intraocular pressure, maintain retinal integrity, recover pupil function, recover retinal ischemia, and corneal injuries (i.e., maintained transparency after complete corneal abrasion, corneal ulceration, and counteracted dry eye after lacrimal gland removal or corneal insensitivity). The most important point is that in glaucomatous rats (three of four episcleral veins cauterized) with high intraocular pressure, all BPC 157 regimens immediately normalized intraocular pressure. BPC 157-treated rats exhibited normal pupil diameter, microscopically well-preserved ganglion cells and optic nerve presentation, normal fundus presentation, nor- mal retinal and choroidal blood vessel presentation, and normal optic nerve presentation. The one episcleral vein rapidly upgraded to accomplish all functions in glaucomatous rats may correspond with occlusion/occlusion-like syndromes of the activated rescuing collateral pathway (azygos vein direct blood flow delivery). Normalized intraocular pressure in glaucomatous rats corresponded to the counteracted intra-cranial (superior sagittal sinus), portal, and caval hypertension, and aortal hypotension in occlusion/occlusion-like syndromes, were all attenuated/eliminated by BPC 157 therapy. Furthermore, given in other eye disturbances (i.e., retinal ischemia), BPC 157 instantly breaks a noxious chain of events, both at an early stage and an already advanced stage. Thus, we further advocate BPC 157 as a therapeutic agent in ocular disease.

A Randomized, Double-Masked, Active-Controlled, Crossover Phase III Equivalence Study of Generic Dorzolamide 2% versus Innovator Trusopt® Eye Drop Solution in Subjects with Open-Angle Glaucoma or Ocular Hypertension

Background

The aim of this study was to demonstrate the equivalence of generic dorzolamide 2% eye drops solution versus the innovator formulation (Trusopt® eye drops solution) in patients with open-angle glaucoma or ocular hypertension.

Methods

This prospective, monocentric, double-masked, active-controlled crossover phase III study included 32 patients. After washout, patients were randomized to reference product (Trusopt®) or test product (dorzolamide 2% eye drops, Rompharm Company SRL) for a 4-week period. Subsequent washout and crossover were performed. Drops were applied t.i.d. The primary efficacy endpoint was the difference in mean diurnal IOP. Goldmann applanation tonometry was performed at 8 am, 12 pm, and 4 pm at each visit, and safety was assessed by documentation of adverse events (AEs). Therapy adherence was documented by self-reporting and eye drop bottle weighing. An ANOVA with treatment, sequence, study period, and patient within the sequence as effects was performed and an additional post hoc ANCOVA including the baseline IOP was also performed.

Results

34 patients were randomized and analyzed in the safety population. The per-protocol population included 32 patients. According to the self-report, all patients were >80% compliant. Under the ANCOVA model, the 90% confidence interval for the average change of the IOP −0.27 mmHg (−1.17 mmHg–0.64 mmHg) is included by the acceptance range −1.5 mmHg to +1.5 mmHg after excluding 2 patients, which had falsely reported high therapy adherence. No clinically relevant difference was observed in frequency or severity of the AEs between both treatments.

Conclusions

This study showed the equivalence of the tested generic dorzolamide 2% eye drops solution to the reference product Trusopt® eye drops solution. Trial Registration. This trial is registered with (ClinicalTrials.gov (identifier: NCT00878917) on April 9, 2009).

Efficacy and safety of timolol-dorzolamide fixed-combination three times a day versus two times a day in newly diagnosed open-angle glaucoma

Objective

This study aimed to compare the therapeutic efficacy and safety of dorzolamide/timolol fixed-combination(Cosopt) in newly diagnosed primary open-angle glaucoma (POAG) patients.

Methods

In this prospective, interventional case series, newly POAG patients were included. Patients were started on Cosopt twice a day (BID) for one month and then switched to three times a day (TDS) for an additional month. Patients underwent comprehensive ophthalmic examination, diurnal intraocular pressure (IOP), blood pressure (BP), and 24-h heart rate (HR) measurements at baseline, month 1(BID), and month 2(TDS). Throughout the study, all adverse events were monitored by the investigators.

Results

In 31 POAG patients that completed the study, the mean baseline IOP was 23.1 ± 3.15 mmHg. IOP was decreased significantly 16.5 ± 2.21 at one month (p < .0001) and 13.9 ± 2.23 mmHg at 1 and 2 months follow up (p < .0001). IOP was significantly lower in month 2 compared to month 1 (p = .0004). While Cosopt BID significantly reduced the mean 24-h systolic BP and mean 24-h HR from baseline (p < .0001), the mean 24-h systolic BP and HR remained unchanged with Cosopt TDS compared to BID (p = .62).

Conclusions

Cosopt TDS has a superior IOP-lowering effect than Cosopt BID in POAG patients with comparable safety profiles.

Comparative Proteomics Analysis of the Postmitochondrial Supernatant Fraction of Human Lens-Free Whole Eye and Liver

The increasing incidence of ocular diseases has accelerated research into therapeutic interventions needed for the eye. Ocular enzymes play important roles in the metabolism of drugs and endobiotics. Various ocular drugs are designed as prodrugs that are activated by ocular enzymes. Moreover, ocular enzymes have been implicated in the bioactivation of drugs to their toxic metabolites. The key purpose of this study was to compare global proteomes of the pooled samples of the eye (n = 11) and the liver (n = 50) with a detailed analysis of the abundance of enzymes involved in the metabolism of xenobiotics and endobiotics. We used the postmitochondrial supernatant fraction (S9 fraction) of the lens-free whole eye homogenate as a model to allow accurate comparison with the liver S9 fraction. A total of 269 proteins (including 23 metabolic enzymes) were detected exclusively in the pooled eye S9 against 648 proteins in the liver S9 (including 174 metabolic enzymes), whereas 424 proteins (including 94 metabolic enzymes) were detected in both the organs. The major hepatic cytochrome P450 and UDP-glucuronosyltransferases enzymes were not detected, but aldehyde dehydrogenases and glutathione transferases were the predominant proteins in the eye. The comparative qualitative and quantitative proteomics data in the eye versus liver is expected to help in explaining differential metabolic and physiologic activities in the eye. SIGNIFICANCE STATEMENT: Information on the enzymes involved in xenobiotic and endobiotic metabolism in the human eye in relation to the liver is scarcely available. The study employed global proteomic analysis to compare the proteomes of the lens-free whole eye and the liver with a detailed analysis of the enzymes involved in xenobiotic and endobiotic metabolism. These data will help in better understanding of the ocular metabolism and activation of drugs and endobiotics.

Ocular hypotensive effects of a Rho-associated protein kinase inhibitor in rabbits

Purpose

Ripasudil is a novel Rho-associated protein kinase inhibitor that is used to treat ocular hypertension. However, the comparison of the intraocular pressure (IOP)-lowering effects between ripasudil alone and other ocular hypotensive drugs has not been studied thoroughly. The purpose of this study is to examine the ocular hypotensive effects of 0.4% ripasudil, 2% pilocarpine, 0.5% timolol and 0.1% dorzolamide in rabbits. We also studied the IOP changes when 0.4% ripasudil was combined with 2% pilocarpine, 0.5% timolol or 0.1% dorzolamide.

Methods

One drop of saline solution, 0.4% ripasudil, 0.5% timolol, 2% pilocarpine or 1% dorzolamide or a combination of these agents was applied topically to the left eyes of eight healthy albino rabbits. Posttreatment changes in the IOP of albino rabbits were monitored using a rebound tonometer over a 5-h time course. Changes in IOP after application of saline served as the control. One-way analysis of variance and Dunnett’s post hoc tests were used for statistical analyses.

Results

After topical instillation, 0.4% ripasudil resulted in significant decreases in IOP at 0.5 and 1 h compared with the control group. Treatment with timolol, pilocarpine or dorzolamide had no significant effect on IOP. Treatment with timolol, pilocarpine or dorzolamide in combination with ripasudil resulted in significant reductions in IOP at 1 h. However, none of these agents enhanced the IOP-lowering effects of ripasudil.

Conclusion

Ripasudil has stronger IOP-lowering effects than timolol, pilocarpine or dorzolamide hypotensive agents in our rabbit model. Addition of timolol, pilocarpine or dorzolamide did not enhance the IOP-lowering effects of ripasudil alone.

Glaucoma-Intraocular Pressure Reduction

Medical treatment is a mainstay for the management of glaucoma (Realini 2011; Marquis and Whitson 2005; Hoyng and van Beek 2000). Intraocular pressure (IOP) lowering has been long recognized as and still represents the primary and most widely employed treatment to prevent glaucomatous vision loss (Musch et al. 2011; Leske et al. 2003; The Advanced Glaucoma Intervention Study (AGIS) 2000). Soon after the recognition that "tension" or IOP was related to glaucoma, pharmacological agents were introduced in the mid-1800s, first with the calabar bean (Realini 2011; Proudfoot 2006). Since then, an explosion of pharmacological agents targeting numerous intracellular and molecular signaling pathways has resulted in a plethora of drugs to lower IOP and treat glaucoma. Aqueous humor dynamics provides the basis for understanding each of these medical therapies.

Intra-ocular pressure-lowering effects of a Rho kinase inhibitor, ripasudil (K-115), over 24 hours in primary open-angle glaucoma and ocular hypertension: a randomized, open-label, crossover study

PURPOSE

To investigate the intra-ocular pressure (IOP)-lowering effects of a selective Rho kinase inhibitor, ripasudil (K-115), over 24 hr in patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT).

METHODS

In this multicenter, prospective, randomized, open-label, 3-period, Latin-square crossover clinical study, 28 patients with POAG or OHT whose IOP level was 21 mmHg or higher were subdivided into three groups. Each patient was treated with placebo and ripasudil in concentrations of 0.2 and 0.4%, at 9:00 and 21:00 on day 1 through a total of 3 periods separated by washout periods. IOP was measured at 9:00, 10:00, 11:00, 13:00, 16:00, 19:00, 21:00, 22:00 and 23:00 on day 1, and 1:00, 4:00, 7:00 and 9:00 on day 2 in sitting position using Goldmann applanation tonometer. Main outcome measure was the IOP reduction of placebo and ripasudil from baseline.

RESULTS

The mean IOP reduction was -5.2 mmHg for 0.2%, -6.4 mmHg for 0.4% and -2.0 mmHg for placebo at 2 hr after the first instillation. Also, the corresponding values were -6.8 mmHg for 0.2%, -7.3 mmHg for 0.4% and -4.1 mmHg for placebo at 2 hr after the second instillation. Statistically significant IOP reduction, compared with placebo, was found for both 0.2 and 0.4% from 1 through 7 hr after each instillation. In safety, conjunctival hyperaemia was observed in 22 patients (79%) for 0.2%, 27 patients (96%) for 0.4% and three patients (11%) for placebo.

CONCLUSION

Ripasudil is a promising new topical medication to lower IOP for at least 7 hr after instillations in patients with POAG or OHT.

The placebo effect in early-phase glaucoma clinical trials

PURPOSE

To analyze the extent and prevalence of the placebo effect in prior early-phase glaucoma clinical studies.

METHODS

Articles were evaluated on phase I and II trials of glaucoma medicines that became commercially available after 1977 with a placebo arm that involved glaucoma patients.

RESULTS

We included 23 studies with 23 treatment arms with a total of 1703 patients in articles evaluating 10 different glaucoma medications. This study showed that at 8 AM (n = 18), the average decrease in placebo from untreated baseline was 2.3 ± 1.6 mm Hg (9%), while for the diurnal curve (n = 17), the mean decrease was 1.4 ± 1.1 mm Hg (6%). At 8 AM, 8/18 treatment arms had greater than 2 mm Hg intraocular pressure (IOP) decrease, and all had at least some reduction in IOP. For the diurnal curve, 4 of 17 studies had reduced IOP greater than 2 mm Hg. One treatment arm had no placebo effect.

CONCLUSIONS

This study suggests that a placebo effect is common in glaucoma clinical trials and potentially could limit the ability to evaluate the efficacy of a new medicine.

Comparison of the latanoprost 0.005%/timolol 0.5% + brinzolamide 1% versus dorzolamide 1%/timolol 0.5% + latanoprost 0.005%: a 12-week, randomized open-label trial

Objective

To compare the safety and effectiveness of fixed-combination regimes (latanoprost– timolol and brinzolamide 1% compared to dorzolamide 1%/timolol and latanoprost) in open-angle glaucoma patients after switching from a combination of three topical antiglaucoma eye drops.

Methods

We conducted an open, randomized 12-week multicenter prospective study. We randomly allocated 39 patients who had been treated with three antiglaucoma eye drops (prostaglandin F_2α analogues plus beta-blockers and carbonic anhydrase inhibitors) into two groups. Group A (n = 20) were treated with latanoprost–timolol and brinzolamide 1% therapy and Group B (n = 16) were treated with dorzolamide 1%/timolol and latanoprost. Thirty-six patients completed all 12 weeks of this study. The major clinical parameters measured were intraocular pressure (IOP), conjunctive hyperemia, superficial punctate keratopathy and hyperpigmentation of eyelid at baseline, 4, and 12 weeks. Additionally noted were adverse events and patient preferences, measured using a questionnaire at study initiation and at 12 weeks.

Results

At baseline, IOPs were (Group A: 14.1 ± 2.9 mmHg, B: 14.5 ± 2.9 mmHg; P = 0.658), (Group A: 13.8 ± 2.6 mmHg, B: 14.3 ± 2.8 mmHg; P = 0.715) at 4 weeks, and (Group A: 14.1 ± 2.7 mmHg, B: 14.2 ± 2.7 mmHg; P = 0.538) at 12 weeks. Among the groups, there was no significant difference at any time point after baseline (P = 0.923, 0.951, respectively). All adverse events were not remarkably different after therapy. In regards to patient preference before and after switching therapy, 10 patients (50%) in Group A and 10 patients (63%) in Group B preferred using fixed-combination eye drop therapy.

Conclusions

Effectiveness and safety were maintained in both groups after switching therapy. Overall, patients generally preferred using a fixed-combination therapy.

Mixed treatment comparison of repeated measurements of a continuous endpoint: an example using topical treatments for primary open-angle glaucoma and ocular hypertension

Mixed treatment comparison (MTC) meta-analyses estimate relative treatment effects from networks of evidence while preserving randomisation. We extend the MTC framework to allow for repeated measurements of a continuous endpoint that varies over time. We used, as a case study, a systematic review and meta-analysis of intraocular pressure (IOP) measurements from randomised controlled trials evaluating topical ocular hypotensives in primary open-angle glaucoma or ocular hypertension because IOP varies over the day and over the treatment course, and repeated measurements are frequently reported. We adopted models for conducting MTC in WinBUGS (The BUGS Project, Cambridge, UK) to allow for repeated IOP measurements and to impute missing standard deviations of the raw data using the predictive distribution from observations with standard deviations. A flexible model with an unconstrained baseline for IOP variations over time and time-invariant random treatment effects fitted the data well. We also adopted repeated measures models to allow for class effects; assuming treatment effects to be exchangeable within classes slightly improved model fit but could bias estimated treatment effects if exchangeability assumptions were not valid. We enabled all timepoints to be included in the analysis, allowing for repeated measures to increase precision around treatment effects and avoid bias associated with selecting timepoints for meta-analysis.The methods we developed for modelling repeated measures and allowing for missing data may be adapted for use in other MTC meta-analyses.

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.

Discovery of Potent and Selective Urea-Based ROCK Inhibitors and Their Effects on Intraocular Pressure in Rats

A series of urea-based Rho kinase (ROCK) inhibitors were designed and evaluated. The discovered compounds had excellent enzyme and cellular potency, high kinase selectivity, high aqueous solubility, good porcine corneal penetration, and appropriate DMPK profiles for topical applications as antiglaucoma therapeutics.

Efficacy and safety of travoprost/timolol vs dorzolamide/timolol in patients with open-angle glaucoma or ocular hypertension

Purpose:

To compare the intraocular pressure- (IOP-) lowering efficacy of fixed combinations travoprost 0.004%/timolol 0.5% and dorzolamide 2%/timolol 0.5% in patients with ocular hypertension or open-angle glaucoma.

Methods:

In this prospective, multicenter, double-masked, randomized clinical trial, 319 qualifying patients received either travoprost/timolol once daily in the morning (n = 157) or dorzolamide/timolol twice daily (n = 162). IOP was assessed morning and evening at 2 and 6 weeks. The primary outcome measure was mean diurnal IOP.

Results:

Baseline mean IOP values were similar between groups. Mean pooled diurnal IOP was significantly lower in the travoprost/timolol group (16.5 mmHg ± 0.23) than in the dorzolamide/timolol group (17.3 mmHg ± 0.23; P = 0.011). Mean IOP was significantly lower in the travoprost/timolol group compared to the dorzolamide/timolol group at the 9 AM time point both at Week 2 (P = 0.006) and Week 6 (P = 0.002). The travoprost/timolol combination produced mean IOP reductions from baseline of 35.3% to 38.5%, while the dorzolamide/timolol combination produced mean IOP reductions from baseline of 32.5% to 34.5%.

Conclusions:

The fixed combination travoprost 0.004%/timolol 0.5% dosed once daily in the morning demonstrated superior mean diurnal IOP-lowering efficacy compared to dorzolamide 2%/timolol 0.5% dosed twice daily in patients with ocular hypertension or open-angle glaucoma.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Effects of topical 2% dorzolamide hydrochloride alone and in combination with 0.5% timolol maleate on intraocular pressure in normal feline eyes

OBJECTIVE

To evaluate the effect of topical 2% dorzolamide alone, and in combination with topical 0.5% timolol, on intraocular pressure (IOP) in normal cats.

ANIMALS

Twenty-four healthy Domestic Short-haired cats.

PROCEDURE

Baseline values of IOP were established at 7 am, 10 am, 1 pm, 5 pm and 9 pm during pretreatment phase (days 1-2). During treatment phase (days 3-10) cats received 2% dorzolamide HCl q 12 h in group A (n = 6), q 8 h in group B (n = 6), and combined with 0.5% timolol maleate q 12 h in group C (n = 6). Cats in control group D (n = 6) received artificial tears q 8 h. During treatment phase IOP measurements were continued at the same time-points as in the pretreatment phase.

RESULTS

Mean pretreatment IOP in all cats was 18.46 +/- 2.99 mmHg. Mean IOP decreased significantly (P < 0.0086) in all treatment groups compared to pretreatment values (group A: 16.40 +/- 0.49 mmHg, group B: 16.04 +/- 0.49 mmHg, group C: 17.76 +/- 0.49 mmHg). IOP did not decrease in control group D (18.55 +/- 0.49 mmHg). The difference in IOP between treatment groups (A, B, C) was not statistically significant, but comparison of IOP between each treatment group and the control group was statistically significant (A-D; P = 0.0057; B-D, P = 0.0012; C-D, P = 0.0212).

CONCLUSION

Topical 2% dorzolamide significantly lowers IOP in normal cats but the effect is mild. Concomitant application of 2% dorzolamide and 0.5% timolol does significantly decrease IOP, but the effect is not significantly greater than q 8 h administration of dorzolamide alone.

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.

Efeitos maleato de timolol 0.5% do cloridrato de dorzolamida 2%, e da associação de ambas na pressão intra-ocular

Avaliaram-se efeitos da dorzolamida do timolol e da combinação de ambos sobre pressão intra-ocular (PIO) de cães normais, além de alterações no olho contralateral, não-tratado. Foram utilizados 60 cães sadios, distribuídos em três grupos (G) de 20 animais. No primeiro grupo (GT), foi avaliada a ação do maleato de timolol 0,5% na PIO; no segundo (GD), a ação do cloridrato de dorzolamida 2%; e, no terceiro (GTD), o efeito da associação fixa timolol/dorzolamida. A PIO foi aferida utilizando-se tonômetro de aplanação (Tonopen®), uma hora antes e uma, duas, quatro, seis e oito horas após a instilação do colírio em análise no olho esquerdo. O efeito da associação timolol/dorzolamida foi mais intenso (27%) que os efeitos do timolol (21,9%) e da dorzolamida (22,4%) na redução da PIO. No olho contralateral, verificou-se redução de 7% no GT, 13,8% no GD e 13,6% no GTD, após quatro e duas horas da administração.

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.

X-ray crystallographic studies reveal that the incorporation of spacer groups in carbonic anhydrase inhibitors causes alternate binding modes

Human carbonic anhydrases (CAs) are well studied targets for the development of inhibitors for pharmaceutical applications. The crystal structure of human CA II has been determined in complex with two CA inhibitors (CAIs) containing conventional sulfonamide and thiadiazole moieties separated by a -CF2- or -CHNH2- spacer group. The structures presented here reveal that these spacer groups allow novel binding modes for the thiadiazole moiety compared with conventional CAIs.

The efficacy and ocular discomfort of substituting brinzolamide for dorzolamide in combination therapy with latanoprost, timolol, and dorzolamide

PURPOSE

The aim of this study was evaluate the efficacy and ocular discomfort of substituting brinzolamide for dorzolamide in patients with glaucoma treated by latanoprost, timolol, and dorzolamide.

METHODS

An 8-week, prospective, randomized, open-label, comparative study was performed in 58 patients with primary open-angle glaucoma treated by latanoprost, timolol, and dorzolamide. These patients were randomly enrolled into two groups: (1) dorzolamide three times daily was substituted with brinzolamide twice-daily (substituting group); and (2) dorzolamide three times daily was continued (control group). Intraocular pressure (IOP) was measured at baseline, 4, and 8 weeks after the enrollment. Subjective ocular discomfort (irritation and blurred vision) at the time of the instillation of the patient was noted with interview.

RESULTS

The IOPs at baseline, 4 and 8 weeks after the enrollment were 17.7 +/- 2.7 mmHg, 17.5 +/- 2.6 mmHg, and 17.4 +/- 2.9 mmHg in the substituting group, and 18.0 +/- 2.5 mmHg, 17.8 +/- 2.5 mmHg, and 17.9 +/- 2.6 mmHg in the control group, respectively. There were no significant differences in IOP changes between the two groups (P = 0.74). In the substituting group, ocular irritation was decreased significantly (P = 0.0014) from 63% to 20%. The slight increase of blurred vision from 27% to 37% that occurred in the substituting group was not significant (P = 0.58). In the control group, neither ocular irritation (P = 0.58, from 68% to 57%) nor blurred vision (P = 0.99, from 25% to 21%) was changed.

CONCLUSIONS

Substituting brinzolamide for dorzolamide maintained stable IOP with improvement in ocular comfort in patients with glaucoma.

The Efficacy and Safety of Topical Brinzolamide and Dorzolamide When Added to the Combination Therapy of Latanoprost and a Beta-Blocker in Patients with Glaucoma

PURPOSE

Brinzolamide and dorzolamide are often used as adjunctive therapy to other antiglaucoma agents. The purpose of this study was to compare the efficacy and safety of brinzolamide 1% versus dorzolamide 1% when added to the combination therapy of latanoprost and a beta-blocker in patients with glaucoma.

METHODS

An 8-week, randomized, open-label comparative study was performed in 52 patients with glaucoma. Brinzolamide 1% (twice a day) or dorzolamide 1% (3 times a day) was randomly administered to the patients who had been treated with both latanoprost and a betablocker.

RESULTS

Intraocular pressure (IOP) were both decreased significantly (P < 0.0001) from 18.6 +/- 2.3 mmHg to 16.7 +/- 2.3 mmHg and from 18.4 +/- 2.6 mmHg to 16.6 +/- 2.5 mmHg, respectively, 8 weeks after the addition of brinzolamide or dorzolamide. However, the difference between the groups was not significant (P = 0.86). The incidence of ocular irritation was significantly higher (P < 0.0001) in the dorzolamide group (74%) than the brinzolamide group (16%), but there was no significant difference in blurred vision between the groups (dorzolamide 37% versus brinzolamide 52%, P = 0.40).

CONCLUSIONS

We concluded that the efficacy of brinzolamide 1% was equivalent to dorzolamide 1%; however, the safety of brinzolamide 1% was superior to dorzolamide 1% as adjunctive therapy to the combination with latanoprost and a beta-blocker.

Short-term ocular tolerability of dorzolamide 2% and brinzolamide 1% vs placebo in primary open-angle glaucoma and ocular hypertension subjects

PURPOSE

To compare ocular tolerability of dorzolamide 2%, brinzolamide 1%, and placebo given three times daily.

METHODS

A prospective, double-masked, three-centre, crossover comparison in which 25 ocular hypertensive or primary-open angle glaucoma subjects were randomized to receive dorzolamide, brinzolamide, or placebo three times daily for 3 days. Intraocular pressure, visual acuity, a visual analogue scale, and ocular and systemic symptom queries were completed at the end of each period.

RESULTS

After chronic dosing, there was a significant difference in ocular pain on the visual analogue scale among the groups at the 10-s postinstillation time point with dorzolamide having the highest level (22.5+/-28.9) compared to brinzolamide (5.0+/-8.7) or placebo (3.2+/-10.4) (P=0.0006). No differences between groups were observed preinstillation nor following dosing at 3 or 10-min postinstillation. On the initial instillation, the 10-s postinstillation pain was rated as 43.3+/-77.1, which was significantly higher than after chronic dosing (P=0.017). On the ocular symptom query, dorzolamide had the highest incidence of burning/stinging and redness compared to the other groups, but was generally characterized as mild. There were no significant differences in the visual acuity at any time point.

CONCLUSIONS

This study suggests that subjects treated with dorzolamide suffer more ocular pain upon instillation compared to brinzolamide or placebo. However, pain symptoms are fewer following chronic dosing and are generally characterized as mild.

The efficacy and safety of dose escalation of dorzolamide used in combination with other topical antiglaucoma agents

We investigated the dose-escalation profile of dorzolamide used in combination with other antiglaucoma agents in patients with primary glaucoma and ocular hypertension. In a prospective, open-label study, 78 patients received dorzolamide 0.5% in addition to other topical antiglaucoma agents for > or =4 weeks. The concentration of dorzolamide was then escalated to 1.0% and intraocular pressure (IOP) measured every 4 weeks for 12 weeks. Dose escalation of dorzolamide from 0.5% to 1.0% resulted in a significant reduction in IOP throughout the 12 weeks of treatment at the higher dose. Mean baseline IOP was 19.7 mmHg. At 4, 8, and 12 weeks after dose escalation, mean IOP had decreased to 17.8 (-9.4%), 17.6 (-10.8%), and 17.5 (-10.7%) mmHg. No serious drug-related adverse effects were reported. These results indicate that dose escalation of dorzolamide from 0.5% to 1.0% is effective and well tolerated as adjunctive therapy for patients in whom IOP is insufficiently controlled by combination therapy.

Retinal Peripapillary Blood Flow before and after Topical Brinzolamide

PURPOSE

To study the effect of topical brinzolamide on retinal capillary blood flow by the Heidelberg Retina Flowmeter (HRF) in patients with glaucoma.

METHODS

Twenty patients with glaucoma were consecutively recruited. One eye for each patient was randomly selected. Patients were classified as glaucomatous if they had an abnormal visual field and/or an abnormal optic nerve head with an intraocular pressure (IOP) greater than 21 mm Hg without any treatment. After an eye examination, baseline retinal blood flow measurements were made with confocal scanning laser Doppler flowmetry. Blood flow and IOP measurements were then repeated after 1 month of treatment. Blood flow measurements were analyzed by using an automatic full-field perfusion image analysis (AFFPIA) program. The blood flow was calculated in the superior and inferior part of the optic disk. In each area, the blood flow was calculated as temporal area, the nasal area and the rim area as for software AFFPIA.

RESULTS

The mean age of the patients was 56 +/- 7 (mean +/- standard deviation) years. The mean IOP before treatment was 23.7 +/- 1.5 mm Hg while the mean IOP after 4 weeks of treatment was 19.1 +/- 2.2 mm Hg. This difference was statistically significant (p < 0.01). Significant (p < 0.05) increases in retinal blood flow were found for the temporal and nasal areas between baseline and 1 month after the treatment. No difference was found between superior and inferior sectors.

CONCLUSION

Topical brinzolamide reduced the IOP significantly and apparently improved retinal blood flow as measured by the HRF.

Brimonidine purite 0.15% versus dorzolamide 2% each given twice daily to reduce intraocular pressure in subjects with open angle glaucoma or ocular hypertension

BACKGROUND/AIMS

To evaluate the efficacy of brimonidine purite versus dorzolamide given twice daily in primary open angle glaucoma or ocular hypertensive subjects.

METHODS

In this double masked, multicentre, prospective, crossover comparison 33 subjects were randomised to brimonidine purite or dorzolamide for the first 4 week treatment period after a 4 week washout. Subjects began the opposite treatment for the second 4 week period after another 4 week washout. Intraocular pressure (IOP) was measured at 08:00 (trough) and 10:00, 18:00, and 20:00 hours after dosing at each baseline and at the end of each treatment period.

RESULTS

The baseline diurnal IOP was 22.9 (SD 2.8) for brimonidine purite and 22.2 (SD 2.4) mm Hg for dorzolamide. The trough IOP following 4 weeks of therapy was 21.0 (SD 3.7) for brimonidine purite and 21.0 (SD 3.1) mm Hg for dorzolamide (p = 0.90). The mean diurnal IOP was 19.3 (SD 3.1) for brimonidine purite and 19.8 (SD 2.4) mm Hg for dorzolamide (p = 0.46). Dorzolamide caused more ocular stinging upon instillation (n = 8) than brimonidine purite (n = 1) (p = 0.02). No statistical differences existed between groups for systemic adverse events.

CONCLUSIONS

This study suggests that brimonidine purite and dorzolamide each given twice daily have similar efficacy in primary open angle glaucoma or ocular hypertensive subjects. However, a trend was observed at 10:00 of greater brimonidine purite efficacy compared with dorzolamide.

Studies on the mechanism of action of timolol and on the effects of suppression and redirection of aqueous flow on outflow facility

Long-term use of drugs that suppress aqueous humor formation, such as timolol and dorzolamide, or that redirect aqueous humor outflow from the trabecular meshwork, such as prostaglandin F2alpha analogues, could cause underperfusion of the trabecular meshwork and a secondary decrease in outflow facility. We investigated the mechanism of suppression of aqueous humor formation by timolol in monkey eyes by measuring aqueous humor ascorbate levels. We also determined whether suppression of aqueous humor formation with and without redirection of aqueous humor away from the trabecular meshwork could lead to a subsequent reduction in outflow facility, and whether this reduction was correlated with increased fibronectin levels in anterior chamber aqueous humor. In cynomolgus monkeys, unilateral dose/aqueous humor formation response curves were generated for timolol, dorzolamide, and a combination of timolol + dorzolamide. Aqueous humor formation and/or outflow facility were measured in both eyes after approximately four days, four weeks and seven weeks of twice daily treatment with 3.5 microg timolol + 1.0 mg dorzolamide to one eye and 30% DMSO to the other. In some monkeys, 5 microg prostaglandin F2alpha-isopropyl ester (PG) was added to timolol + dorzolamide for 4-week treatments. Intraocular pressure and corneal endothelial transfer coefficients (k(a)) were also measured at four weeks. Aqueous humor fibronectin levels were determined in four monkeys after approximately 9.5 weeks of timolol + dorzolamide treatment. Aqueous humor formation, intraocular pressure, and aqueous humor ascorbate levels were also determined in rhesus monkeys at baseline and after a single unilateral topical administration of 25 microg timolol. Compared to baseline for the same eye, aqueous humor formation was significantly decreased in treated eyes at all doses of timolol and at 1.8 and 4 mg dorzolamide. Compared to the opposite control eye, aqueous humor formation was lower in treated eyes after 3.5 and 5 microg timolol and after all doses of dorzolamide. Aqueous humor formation after treatment with 3.5 microg timolol + 1.0 mg dorzolamide was decreased in treated vs. control eyes, after four days and was suppressed in both treated and control eyes after four weeks of treatment, but not when PG was added. There was no difference in k(a) values with or without the addition of PG. Intraocular pressure was significantly lower in both treated and control eyes vs. baseline after approximately 6.5 weeks treatment with timolol + dorzolamide when taken 2 hr after the last dose and after approximately 3.5 weeks treatment with timolol + dorzolamide + PG when measured 6 hr after the last dose. Outflow facility after treatment with timolol + dorzolamide was unchanged after four days, tended to be lower in the treated vs. control eyes after four and seven weeks, and was significantly lower in treated vs. control eyes after four weeks treatment with timolol + dorzolamide + PG (0.352 +/- 0.052 vs. 0.515 +/- 0.096 microl min(-1) mmHg(-1), p < or = 0.02). Both treated vs. control eye aqueous humor fibronectin levels were below the level of detection for our assay (0.01 microg ml(-1)). The 25 microg timolol dose decreased ipsilateral, but not contralateral intraocular pressure (12.6 +/- 1.7 vs. 15.2 +/- 0.9; p < 0.05) and aqueous humor formation (1.40 +/- 0.08 vs. 2.03 +/- 0.09 microg ml(-1), p < or = 0.01). There was no difference in anterior chamber ascorbate levels in treated vs. control eyes or compared to their respective baselines. Our findings indicate that timolol affects neither ciliary epithelial transport of ascorbate nor aqueous fibronectin levels. Our data also indicate that decreasing aqueous humor formation over a period of time can lead to reduction in outflow facility, particularly when combined with therapy that redirects aqueous from the trabecular meshwork. Future intraocular pressure-lowering therapies for glaucoma may better be directed at enhancing flow through the trabecular pathway as opposed to decreasing aqueous humor formation or rerouting aqueous humor away from the trabecular meshwork.

Comparison of the safety and efficacy of dorzolamide 2% and brimonidine 0.2% in patients with glaucoma or ocular hypertension

PURPOSE

To compare the intraocular pressure (IOP) reduction between dorzolamide 2% and brimonidine 0.2% in primary open-angle glaucoma (POAG) or ocular hypertension (OHT).

METHODS

This study was a prospective, double-masked, randomized, crossover comparison of dorzolamide 2% (Trusopt) and brimonidine 0.2% (Alphagan), three times daily during two six-week study periods. The primary endpoint was mean change from baseline in trough IOP and secondary endpoints were mean change from baseline in IOP one and three hours after dosing. T-tests and a repeated-measures ANOVA were used to statistically evaluate the data.

RESULTS

Of 43 patients enrolled, 41 completed the first treatment and 38 completed both treatments. Baseline IOP for dorzolamide was 24.3 mm Hg and brimonidine, 24.6 mm Hg (P = 0.9). Mean IOP reduction at trough was similar for both agents, 3.0 mm Hg (P = 0.96). Reductions at one and three hours were comparable (P = ns). Both agents were well tolerated with adverse events consistent with the package inserts. Dorzolamide was associated with more frequent stinging (P = 0.017) and burning (P < 0.001), while brimonidine was associated with more frequent dry eye (P = 0.04).

CONCLUSIONS

Dorzolamide and brimonidine, as monotherapy, produced equivalent IOP-lowering efficacy at trough and at one and three hours after instillation, and both were well tolerated.

Effects of topical administration of 1% brinzolamide on normal cat eyes

OBJECTIVE

To evaluate the effect of short-term daily topical administration of 1% brinzolamide on the intraocular pressure (IOP) of healthy domestic cats with normotensive eyes and to assess the potential for negative side effects of drug administration.

ANIMALS

Twelve privately owned adult domestic cats without physical or ocular abnormalities.

PROCEDURE

Normal variation in IOP was determined on day 1. Cats were then treated on days 2-8 with a topical placebo (artificial tear solution) OU q 12 h. On days 9-15 the cats were treated q 12 h with 1% brinzolamide in one randomly selected eye and the placebo in the contralateral eye. All medications (drug and placebo) were administered twice daily at 7 a.m. and 7 p.m. On days 16-22 the cats received no topical medications. IOP, horizontal pupil size in mm and assessment of conjunctival hyperemia were noted OU on days 1, 8, 15 and 22 at 5 time points (9 a.m., 11 a.m., 1 p.m., 3 p.m. and 5 p.m.). Mixed linear regression models were used to compare the IOP of each eye at all time periods for each cat, controlling for age and weight.

RESULTS

Mean IOP was not significantly altered in any eye at any time point during the treatment period compared with pretreatment, baseline, or follow-up evaluations. Conjunctival hyperemia and miosis were not detected in either eye at any time point. Conclusions and clinical relevance Short-term q 12 h administration of 1% brinzolamide did not significantly reduce IOP in this small sample population of normotensive cats under these study conditions. No clinically relevant side effects were noted with brinzolamide administration.

Timolol 0.5%/dorzolamide 2% fixed combination versus timolol 0.5%/pilocarpine 2% fixed combination in primary open-angle glaucoma or ocular hypertensive patients

PURPOSE

To establish the efficacy and safety of timolol maleate/dorzolamide fixed combination (TDFC) versus timolol maleate/pilocarpine fixed combination (TPFC), each given twice daily, in primary open-angle glaucoma or ocular hypertensive patients.

METHODS

In this prospective, multicentred, double-masked trial, 37 patients were treated twice daily with timolol for 4 weeks. They were then randomized to one of the treatment medications for 6 weeks, after which they were treated with timolol again for 2 weeks before being placed on the opposite treatment medication for 6 weeks.

RESULTS

A total of 36 patients completed the trial. Their mean baseline intraocular pressure (IOP) was 22.3 +/- 3.7 mmHg. Following 6 weeks of treatment, the mean trough (08.00 hours) IOP was 18.0 +/- 2.2 mmHg for TDFC and 17.4 +/- 2.0 mmHg for TPFC (p = 0.22). The mean diurnal curve IOP was 18.1 +/- 2.2 mmHg for TDFC and 16.7 +/- 1.9 mmHg for TPFC (p = 0.0007). At the remaining time-points (10.00, 18.00 and 20.00 hours), TPFC IOPs were statistically lower than TDFC IOPs (p < 0.03). There were statistically more unsolicited reports of vision change and ocular pain associated with TPFC (p = 0.04). Six patients were discontinued early from TPFC therapy (17%) versus two from TDFC (6%) (p = 0.13).

CONCLUSIONS

This study suggests that TPFC can provide at least a similar efficacious reduction in IOP as TDFC in patients with primary open-angle glaucoma or ocular hypertension.

Effects of twice daily application of 2% dorzolamide on intraocular pressure in normal cats

The effect of the topical carbonic anhydrase inhibitor, dorzolamide, on intraocular pressure in cats was studied. The intraocular pressure of both eyes of eight healthy cats was measured using applanation tonometery (Tono-Pen) during two phases: control and treatment. Both eyes were treated with 2% dorzolamide twice a day during the treatment phase. Application of dorzolamide resulted in a significant decrease of intraocular pressure over the treatment phase. By the fourth and fifth day of treatment, the mean intraocular pressure (+/- standard deviation) was 9.7 (+/- 1.5) mmHg, whereas the mean (+/- standard deviation) for the last 2 days of the control period was 12.2 (+/- 2.0) mmHg. Based on this study, dorzolamide is a potentially effective treatment for glaucoma in cats, significantly lowering intraocular pressure.

Acute and chronic ocular symptoms of dorzolamide 2% compared with placebo

PURPOSE

To characterize and compare the ocular comfort and symptoms of dorzolamide and tear-replacement drops (placebo) in healthy volunteers.

PATIENTS AND METHODS

Subjects were randomized in a double-masked fashion to receive each medicine for 6 days twice daily. Patients used a visual analog scale to assess the quality and intensity of pain temporally after initial (acute) dosing and after 6 days of chronic dosing. The visual analog scale, an objective measure of pain, allows a subject to grade their perceived intensity of pain on a line between 0 and 100 mm.

RESULTS

Of 28 subjects enrolled in the study, 27 completed the protocol (1 subject was lost to follow-up). Dorzolamide demonstrated statistically greater peak ocular pain (21.4 +/- 22.3 mm) compared with placebo (1.9 +/- 4.4 mm) (P<0.0001) after chronic dosing. Time of mean peak pain for dorzolamide products was 15 seconds after dosing. The pain was statistically greater with dorzolamide compared with placebo for 50 seconds after dosing. On average the discomfort associated with dorzolamide lasted 38.9 +/- 17.9 seconds after dosing. The average pain per second for the first minute was 7.1 +/- 10.1 mm for dorzolamide. No differences in pain intensity were observed after acute and chronic dosing. The discomfort with dorzolamide was characterized after chronic dosing as "burning" (14.8 +/- 25.0 mm) and was associated with tearing (1.9 +/- 5.2 mm).

CONCLUSION

Dorzolamide caused more ocular pain after instillation than placebo. However, the pain was characterized as mild and quickly resolved.

Tolerability and efficacy of dorzolamide versus acetazolamide added to timolol

PURPOSE

Evaluate the safety and efficacy of dorzolamide versus acetazolamide when added to once daily 0.5% timolol maleate ophthalmic gel forming solution (timolol gel).

METHODS

This was a randomized, double-masked, multicenter, active-controlled, parallel group study of 215 patients with open-angle glaucoma or ocular hypertension. Following a two-week treatment period with timolol gel, patients with IOP > or = 22 mm Hg and who tolerated one week of acetazolamide 250-mg q.i.d. either were randomized to acetazolamide or dorzolamide 2% three times daily for 12 weeks.

RESULTS

In 155 randomized patients (dorzolamide, N = 80, acetazolamide, N = 75), compared to the dorzolamide, acetazolamide had a statistically greater number of systemic adverse events (dorzolamide 50%, acetazolamide 75%, p = 0.001), adverse events associated with carbonic anhydrase inhibitor (CAI) therapy (dorzolamide 26%, acetazolamide 53%, p < 0.001) and discontinuations due to CAI adverse experiences (dorzolamide 8%, acetazolamide 24%, p = 0.007). Intent to treat analysis found that changes from baseline in IOP were similar at both troughs (dorzolamide 1.4 +/- 0.46 mm Hg, acetazolamide 0.8 +/- 0.47 mm Hg, p = 0.386). However, per-protocol analysis found statistically improved pressure control with acetazolamide (0.1 +/- 0.42 mm Hg) compared to dorzolamide (1.9 +/- 0.43 mm Hg) (p = 0.009).

CONCLUSIONS

This study found a greater incidence of systemic and CAI adverse experiences and discontinuations due to acetazolamide compared to dorzolamide.

Dorzolamide and ocular blood flow in previously untreated glaucoma patients: a controlled double-masked study

PURPOSE

The aim of this study was to investigate the haemodynamic effects of topical dorzolamide treatment in eyes with newly detected and previously untreated glaucoma.

METHODS

Forty-seven patients with open angle glaucoma were consecutively randomized to dorzolamide versus placebo TID during a 6-week double-masked treatment trial. Ocular blood flow was investigated at baseline and on therapy using colour Doppler imaging of the retrobulbar vessels and scanning laser ophthalmoscope fluorescein angiograms of the retinal circulation.

RESULTS

None of the flow parameters, retrobulbar or retinal, changed significantly on therapy when the results were analysed with the Bonferroni method. Analysis with non-simultaneous tests also failed to reveal any significant changes either in retrobulbar flow velocities in the central retinal artery, ophthalmic artery or in the short posterior ciliary arteries, or in the retinal parameters (arm-retina time, arteriovenous passage time, mean dye velocity or macular capillary velocity), while capillary velocities at the optic disc decreased significantly in the dorzolamide group (P = 0.03). Intraocular pressure reduction was significantly more pronounced in the dorzolamide group (P = 0.002), with - 4.8 +/- 2.9 mmHg (P < 0.0001) versus -1.8 +/- 3.0 mmHg in the placebo group (P = 0.006).

CONCLUSIONS

The present study indicated no measurable vascular effects from topical dorzolamide treatment in previously untreated glaucoma eyes.

Structural aspects of isozyme selectivity in the binding of inhibitors to carbonic anhydrases II and IV

Carbonic anhydrase inhibitors are effective in lowering intraocular pressure, the primary indication of glaucoma. Human carbonic anhydrase II, and possibly carbonic anhydrase IV (CAII and CAIV, respectively), help regulate fluid secretion into the anterior chamber of the eye. Because inhibitors currently formulated as drugs to treat glaucoma were designed to target CAII, an understanding of the structural basis of CAII-CAIV discrimination by inhibitors would be useful for probing the role of each isozyme in the etiology of the disease. Here, we report the X-ray crystal structures of three novel thieno[3,2-e]-1,2-thiazine-6-sulfonamides complexed with CAII and the computationally predicted structures of the same compounds complexed with CAIV. All three compounds bind with similar affinity to CAII, but they bind with up to 100-fold lower affinities to CAIV. Comparisons of experimentally determined structures of CAII-inhibitor complexes and computationally predicted structures of CAIV-inhibitor complexes allow us to rationalize these affinity trends and outline molecular features that may contribute to high-affinity inhibitor binding to CAIV. This study demonstrates how experimental structure determination methods and computational structure prediction methods can be used together to answer questions that cannot be answered by either method alone.

Effects of topical application of a 2% solution of dorzolamide on intraocular pressure and aqueous humor flow rate in clinically normal dogs

OBJECTIVE

To evaluate effects of topical application of a 2% solution of dorzolamide on intraocular pressure (IOP) and aqueous humor flow rate in clinically normal dogs.

ANIMALS

15 Beagles.

PROCEDURE

The IOP was measured in both eyes of all dogs for 3 days to determine baseline values. In a single-dose study, 50 microl of dorzolamide or control solution was applied in both eyes at 7:00 AM, and IOP was measured 7 times/d. In a multiple-dose study, dorzolamide or control solution was applied to both eyes 3 times/d for 6 days, and IOP was measured 4 times/d during treatment and for 5 days after cessation of treatment. Aqueous humor flow rate was measured for all dogs fluorophotometrically prior to treatment and during the multiple-dose study.

RESULTS

In the single-dose study, dorzolamide significantly decreased IOP from 30 minutes to 6 hours after treatment. Mean decrease in IOP during this time span was 3.1 mm Hg (18.2%). Maximal decrease was detected 6 hours after treatment (3.8 mm Hg, 22.5%). In the multiple-dose study, dorzolamide decreased IOP at all time points, and maximal decrease was detected 3 hours after treatment (4.1 mm Hg, 24.3%). Mean aqueous humor flow rate decreased from 5.9 to 3.4 microl/min (43%) after treatment in the dorzolamide group.

CONCLUSIONS AND CLINICAL RELEVANCE

Topical application of a 2% solution of dorzolamide significantly decreases IOP and aqueous humor flow rate in clinically normal dogs. Therefore, topical administration of dorzolamide should be considered for the medical management of dogs with glaucoma.

Effect of topical administration of 2% dorzlamide hydrochloride or 2% dorzlamide hydrochloride-0.5% timolol maleate on intraocular pressure in clinically normal horses

OBJECTIVE

To evaluate the effect of topical administration of 2% dorzolamide hydrochloride or 2% dorzolamide hydrochloride-0.5% timolol maleate on intraocular pressure (IOP) in clinically normal horses.

ANIMALS

18 healthy adult horses without ocular abnormalities.

PROCEDURE

The IOP was measured at 5 time points (7 AM, 9 AM, 11 AM, 3 PM, 7 PM) over 11 days. On days 1 and 2, baseline values were established. On days 3 through 5, horses received 2% dorzolamide HCI (group D, n = 9) or 2% dorzolamide HCl-0.5% timolol maleate (group DT, 9) in 1 randomly assigned eye every 24 hours immediately following each daily 7 AM IOP measurement. On days 6 through 9, each drug was given every 12 hours (7 AM and 7 PM) in the treated eye. Measurements on days 10 and 11 assessed return to baseline. Mixed linear regression models compared mean IOP difference for each drug at each time period.

RESULTS

Mean IOP decreased significantly in all eyes during the 2 dose/d period, compared with the baseline, 1 dose/d, and follow-up periods.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of either drug every 24 hours for short-term treatment does not reduce IOP significantly. Administering either drug every 12 hours induced a significant reduction of IOP; however, controlling for all variables, the reduction was less than 2 mm Hg.