Effects of latanoprost and timolol-XE on hydrodynamics in the normal eye

Reexamining Ophthalmic Drugs, Safety and Tolerability in Phase 1 Clinical Trials

Purpose

The purpose of this study was to evaluate the safety and tolerability profile of drugs used for treating common eye disorders when applied to normal healthy volunteers (NHVs) as explored in phase 1 trials.

Subjects and Methods

A total of 166 NHVs were identified in six phase 1 trials, examined in a retrospective analysis. The primary endpoints were visual comfort (by ocular comfort index, OCI) and safety (laboratory evaluations, vital signs (VS), visual acuity (VA), intraocular pressure (IOP), lissamine green and fluorescein staining, conjunctival hyperemia, chemosis, and adverse events’ incidence (AE)).

Results

Compared to baseline, 75.9%, 40.4% and 73.7% of NHV (for lubricant, hypotensive and antibiotic treatments, respectively) improved their OCI score by their final visit. Laboratory evaluations and VS were within normal ranges in 88% of NHV. Similar results were found for VA, corneal and conjunctival staining, and chemosis. IOP decreased significantly in the hypotensive agents’ group, trace to mild hyperemia was reported in 32.1%, 27.1%, and 6.8%, respectively. Additionally, lubricant and hypotensive investigational drugs (ID) had a lower risk of incidence of AE than approved drugs (OR 0.856, 95% CI [0.365, 1.999] and 0.636, 95% CI [0.096, 4.197], respectively). Meanwhile, on antibiotic drugs, the risk for ID-related AE was higher (OR 1.313, 95% CI [0.309, 5.583]).

Conclusion

Phase 1 trials are important in order to ensure the safety and tolerability of ophthalmic medications. This study demonstrates that NHVs do not face a significant risk of harm in these studies, since 98% of the reported AE were mild, and all AE were resolved by the end of the study in which they appeared.

Trial Registration

This is a retrospective study of six previously conducted clinical trials, registered on clinicaltrials.gov with the following registration IDs: NCT04081610, NCT03524157, NCT03520348, NCT03966365, NCT03965052 and, NCT03519516.

Direct and crossover effects of brinzolamide, betaxolol, and latanoprost on choroidal thickness

PURPOSE

To investigate the acute effects of brinzolamide, betaxolol, and latanoprost (drugs commonly used in the medical management of glaucoma) on choroidal thickness using enhanced depth imaging optical coherence tomography (EDI-OCT).

METHODS

Ninety healthy volunteers were evaluated in this prospective study. Participants were randomly divided into 3 groups. Brinzolamide, betaxolol, and latanoprost were administered into the left eyes of the first group (n = 30), second group (n = 30), and third group (n = 30), respectively, and artificial tear (Sodium hyaluronate) was instilled into the right eyes of all participants. Subfoveal choroidal thickness (SFCT) was measured using EDI-OCT before and 45 minutes after administration of the antiglaucomatous drops.

RESULTS

SFCT revealed a significant increase in the left eye (administered antiglaucomatous drop) in the brinzolamide (p = 0.001) and betaxolol groups (p = 0.049) and a significant increase also in the right eye (administered artificial drop) in the brinzolamide (p = 0.001) and betaxolol groups (p = 0.001). However, SFCT did not reveal a significant increase in the left eye (p = 0.213) or in the right eye (p = 0.062) in the latanoprost group.

CONCLUSION

Brinzolamide and betaxolol caused an increase in SFCT, while latanoprost had no significant effect on SFCT.

Bimatoprost sustained-release intracameral implant reduces episcleral venous pressure in dogs

OBJECTIVE

To determine the effect of a bimatoprost sustained-release intracameral implant (Bimatoprost SR) on episcleral venous pressure (EVP) in normal dogs.

METHODS

Normotensive beagle dogs were randomized to receive Bimatoprost SR 30 μg (n = 7) or sham injection (needle insertion only, n = 7) in one eye on day 1. EVP was measured with an episcleral venomanometer through day 65. Episcleral aqueous outflow vessels were identified using fluorescence imaging following intracameral injection of indocyanine green in one additional animal. A separate cohort of dogs that had been trained for conscious intraocular pressure (IOP) measurements received Bimatoprost SR 30 μg (n = 8) in one eye; IOP was evaluated through day 66.

RESULTS

Baseline mean EVP was 10.0 mmHg in the Bimatoprost SR group and 10.4 mmHg in the sham group. Eyes treated with Bimatoprost SR exhibited a transient increase in mean EVP that peaked at day 8, followed by a decrease to levels below baseline. From day 29 to day 65, the change in mean EVP from baseline ranged from -2.4 to -3.9 mmHg (P < 0.05 vs. sham). Baseline mean IOP in eyes treated with Bimatoprost SR was 14.9 mmHg, and a steady IOP reduction was maintained through day 66. Bimatoprost SR-treated eyes exhibited a selective, sustained dilation of aqueous outflow vessels that was not observed in sham-treated eyes.

CONCLUSIONS

In normal dogs, Bimatoprost SR was associated with a transient increase in EVP followed by a sustained decrease. Changes in EVP were accompanied by a sustained dilation of aqueous outflow vessels.

Effects of Betaxolol and Latanoprost on Ocular Blood flow and Visual Fields in Patients with Primary Open-Angle Glaucoma

Purpose

To evaluate the effects of betaxolol and latanoprost on ocular blood flow and visual fields in patients with primary open-angle glaucoma (POAG) by means of an obseiver-masked, prospective clinical study.

METHODS

Thirty-two patients with newly diagnosed POAG were included in the study. The patients were randomized into two groups. The first group was treated with betaxolol 0.50% twice daily and the second group with latanoprost 0.005% once daily. Baseline and post-treatment examinations on the first and third months of treatment included intraocular pressure (IOP) measurement, automated visual field testing, and ocular blood flow assessment. For evaluation of visual fields, mean defect and pattern standard deviation indices were used. Ocular blood flow was assessed by means of color Doppler imaging of the central retinal artery (CRA) and the temporal short posterior ciliary artery (PCA). For each vessel, peak systolic (PSV) and end-diastolic (EDV) blood flow velocities were measured and resistivity index (RI) calculated.

Results

After exclusion of one noncompliant patient, the study was completed with 31 eyes of 31 patients. Both drugs significantly reduced IOP (p<0.05). The mean IOP lowering effect of latanoprost was significantly higher than that of betaxolol (p=0.03). Visual field indices exhibited no significant changes in either group (p>0.05). There were no significant changes in PSV or EDV measurements of CRA or PCA in either group (p>0.05). RI decreased in both CRA and PCA with both drugs. The mean changes between baseline and 3 month blood flow measurements were not significantly different between betaxolol and latanoprost (p>0.05).

CONCLUSIONS

Over a treatment period of 3 months, both betaxolol and latanoprost tended to improve ocular blood flow without one of them being superior to the other. The results suggest that the direct (non IOP-dependent) influence on ocular circulation is better for betaxolol than for latanoprost. In addition, neither drug caused significant generalized improvements in visual fields during this period.

Effect of Cromakalim Prodrug 1 (CKLP1) on Aqueous Humor Dynamics and Feasibility of Combination Therapy With Existing Ocular Hypotensive Agents

Purpose

Cromakalim prodrug 1 (CKLP1) is a water-soluble ATP-sensitive potassium channel opener that has shown ocular hypotensive properties in ex vivo and in vivo experimental models. To determine its mechanism of action, we assessed the effect of CKLP1 on aqueous humor dynamics and in combination therapy with existing ocular hypotensive agents.

Methods

Outflow facility was assessed in C57BL/6 mice by ex vivo eye perfusions and by in vivo constant flow infusion following CKLP1 treatment. Human anterior segments with no trabecular meshwork were evaluated for effect on pressure following CKLP1 treatment. CKLP1 alone and in combination with latanoprost, timolol, and Rho kinase inhibitor Y27632 were evaluated for effect on intraocular pressure in C57BL/6 mice and Dutch-belted pigmented rabbits.

Results

CKLP1 lowered episcleral venous pressure (control: 8.9 ± 0.1 mm Hg versus treated: 6.2 ± 0.1 mm Hg, P < 0.0001) but had no detectable effect on outflow facility, aqueous humor flow rate, or uveoscleral outflow. Treatment with CKLP1 in human anterior segments without the trabecular meshwork resulted in a 50% ± 9% decrease in pressure, suggesting an effect on the distal portion of the conventional outflow pathway. CKLP1 worked additively with latanoprost, timolol, and Y27632 to lower IOP, presumably owing to combined effects on different aspects of aqueous humor dynamics.

Conclusions

CKLP1 lowered intraocular pressure by reducing episcleral venous pressure and lowering distal outflow resistance in the conventional outflow pathway. Owing to this unique mechanism of action, CKLP1 works in an additive manner to lower intraocular pressure with latanoprost, timolol, and Rho kinase inhibitor Y27632.

Ocular hypotensive safety and systemic absorption of AR-13324 ophthalmic solution in normal volunteers

PURPOSE

To evaluate the ocular and systemic safety and systemic absorption of AR-13324 in normotensive, healthy volunteers.

DESIGN

Open-label, noncomparative, single-arm phase 1 clinical trial.

METHODS

setting: Phase 1 clinical trials unit. patient or study population: Eighteen normal adult volunteers. intervention or observation procedures: Subjects received AR-13324 ophthalmic solution 0.02% once daily in the morning in each eye for 8 days.

MAIN OUTCOME MEASURES

Plasma concentrations of AR-13324 and its presumed human metabolite, AR-13503, and ocular safety measures.

RESULTS

There were no observed plasma AR-13324 concentrations higher than the lower limit of quantitation at any time point in any subject. Only 1 plasma sample from 1 subject (day 8 at 8 hours after dose administration) had an AR-13503 concentration higher than the lower limit of quantitation (0.11 ng/mL). AR-13324 dosed once daily in the morning produced substantial reductions in baseline intraocular pressure of up to 6 mm Hg that were statistically significant (P < .001) at all time points after dose administration. All but 1 subject exhibited transient conjunctival hyperemia to some degree in the 8-hour period after morning dosing.

CONCLUSIONS

AR-13324 ophthalmic solution 0.2%, administered once daily in the morning for 8 days, produced little or no quantifiable systemic exposure to the parent compound or a presumed metabolite. Clinically and statistically significant reductions in intraocular pressure were observed in these normotensive subjects that were more pronounced compared with what has been observed commonly with other ocular hypotensive therapies in this population.

Effects of antiglaucoma drugs on blood flow of optic nerve heads and related structures

An association between glaucoma development or progression and compromised ocular blood flow has been postulated as a result of population-based studies and prospective cohort studies. Blood flow in the optic nerve head (ONH) is of primary importance in the pathogenesis of glaucoma. The potential to modify the blood flow in the ONH and its related structures has been reported in various agents, including topical antiglaucoma drugs and systemic drugs such as calcium channel antagonists, which are reviewed in this manuscript. Clinical implications of the improvement in ocular blood flow on the treatment of glaucomatous optic neuropathy require further investigation.

Topical application of 0.005% latanoprost increases episcleral venous pressure in normal dogs

INTRODUCTION

Episcleral venous pressure (EVP) has an important role in intraocular pressure (IOP) homeostasis and accounts for more than 70% of the IOP in the normal dog. A frequently used species in glaucoma research is the normotensive dog especially when evaluating the efficacy of prostaglandin analogues and prostamides; however, aqueous humor dynamic studies in normal dogs are lacking, and the effect of 0.005% latanoprost on canine EVP is not known. We sought to determine the effects to the EVP of topically applied 0.005% latanoprost in the normotensive beagle dog.

METHODS

Female beagle dogs (n = 14) were used and each had a normal ophthalmic examination on study entry. EVP was determined using a standard episcleral venomanometer. Animals were dosed in one eye with 0.005% latanoprost, and the effects on EVP were compared with the averaged baseline EVP's determined in the predosing phase and the fellow nondosed eye. The Mixed Model Repeated Measures method was used to analyze the EVP data.

RESULTS

During the dosing phase of the study with topical 0.005% latanoprost, the mean EVPs of dosed eyes were significantly higher than that of nondosed eyes (P < 0.0001).

CONCLUSIONS

The increase in EVP in the dog with exposure to topical 0.005% latanoprost has not been observed in other species that have been studied, such as in the mouse and in humans, where the drug had no significant effect on the EVP. This response may be unique to dogs and suggests that dogs may not fully mimic human aqueous humor dynamics with topical 0.005% latanoprost. Although frequently performed in human studies, EVP should not be regarded to be a constant value in aqueous humor dynamic studies in the normal beagle dog.

Measurement of episcleral venous pressure

Episcleral venous pressure (EVP) is an important determinant of intraocular pressure (IOP) and can be measured by using various techniques. It has been measured non-invasively by estimating the pressure required to compress an episcleral vein to a predetermined endpoint. However, the lack of objective endpoints makes EVP measurement in humans uncertain, and a wide range of mean EVP has been reported in the literature. We review the evidence for physiologic regulation of EVP and its role in glaucoma therapy, techniques that have been used to measure EVP and the need for objective measurements, and reported values for EVP. We also review recent progress toward developing an objective technique for EVP measurement.

Clinical utility and differential effects of prostaglandin analogs in the management of raised intraocular pressure and ocular hypertension

Prostaglandin analogs (PGA) are powerful topical ocular hypotensive agents available for the treatment of elevated intraocular pressure (IOP). Latanoprost 0.005% and travoprost 0.004% are prodrugs and analogs of prostaglandin F2α. Bimatoprost 0.03% is regarded as a prostamide, and debate continues as to whether it is a prodrug. The free acids of all 3 PGAs reduce IOP by enhancing uveoscleral and trabecular outflow via direct effects on ciliary muscle relaxation and remodeling of extracellular matrix. The vast majority of clinical trials demonstrate IOP-lowering superiority of latanoprost, bimatoprost and travoprost compared with timolol 0.5%, brimonidine 0.2%, or dorzolamide 2% monotherapy. Bimatoprost appears to be more efficacious in IOP-lowering compared with latanoprost, with weighted mean difference in IOP reduction documented in one meta-analysis of 2.59% to 5.60% from 1- to 6-months study duration. PGAs reduce IOP further when used as adjunctive therapy. Fixed combinations of latanoprost, bimatoprost or travoprost formulated with timolol 0.5% and administered once daily are superior to monotherapy of its constituent parts. PGA have near absence of systemic side effects, although do have other commonly encountered ocular adverse effects. The adverse effects of PGA, and also those found more frequently with bimatoprost use include ocular hyperemia, eyelash growth, and peri-ocular pigmentary changes. Iris pigmentary change is unique to PGA treatment. Once daily administration and near absence of systemic side effects enhances tolerance and compliance. PGAs are often prescribed as first-line treatment for ocular hypertension and open-angle glaucoma.

Effects of Topical Travoprost and Unoprostone on Optic Nerve Head Circulation in Normal Rabbits

PURPOSE

To evaluate the effect, and the duration of the effect, of topically administrated travoprost and unoprostone on optic nerve head (ONH) circulation in Dutch rabbits.

METHODS

First, travoprost (0.004% solution) or unoprostone (0.12% solution) was unilaterally instilled once, or once daily (travoprost) or twice daily (unoprostone) for 7 days in Dutch rabbits. The ONH tissue blood velocity (NB(ONH)) was measured using the laser speckle method at 30 and 60 min after a single instillation of travoprost or unoprostone, and before and at 1, 6, and 12 hr (travoprost or unoprostone) and 24 hr (travoprost only) after the last instillation of the aforementioned 7-day instillation regimen. Second, similar experiments were conducted with indomethacin (5 mg/kg) pretreatment.

RESULTS

Both travoprost and unoprostone significantly increased NB(ONH) only in the treated eyes after a single instillation (p = 0.011 to 0.038); this effect was abolished by indomethacin pretreatment. In the 7-day instillation regimen, NB(ONH) was increased by 11%, 40%, 17%, 16%, and 12% only in the treated eyes just before and at 1, 6, 12, and 24 hr after the final instillation of travoprost, respectively, and increased by 10%, 25%, 13%, and 14% only in the treated eyes just before and at 1, 6, 12 hr after the final instillation of the unoprostone, respectively.

CONCLUSIONS

Topical travoprost or unoprostone significantly increased the ONH blood velocity with a single instillation and the effect persisted for 24 hr after a 7-day instillation. The effects of these drugs against retinal and ONH circulation are probably associated with the production of endogenous prostaglandins.

Local effect of topical FP-receptor agonists on retinal vessels of the ipsilateral posterior retina in normal rabbit eyes

PURPOSE

To determine whether a topically instilled prostaglandin analogue inhibits endothelin-1 (ET-1)-induced vasoconstrictive effects in the posterior retina by its local effects, and the duration of the effect in normal rabbit eyes.

METHODS

Travoprost, a potent selective FP-agonist, or unoprostone, a prostone that also has a weak non-selective FP-agonistic activity, solution was instilled once, or once daily (travoprost) or twice daily (unoprostone) for 7 days in one randomly chosen Dutch rabbit eye, and vehicle in the contralateral eye. ET-1 was intravitreously injected in both eyes 30 min after a single instillation of a test drug or its vehicle, or just after, 30, 60, 90 or 180 min after the final instillation of a 7-day instillation, and fundus photographed before, 30 and 60 min after the injection to study whether difference was seen in the ET-1-induced constriction of retinal vessels between the drug- and vehicle-instilled eyes. The same experimental procedures were conducted with indomethacin pretreatment.

RESULTS

In the rabbit eyes where travoprost was instilled for 7 days, the ET-1-induced constriction of retinal vessels was significantly inhibited only on the drug-treated side, when ET-1 was injected 30 or 60 min after the final instillation (P = 0.026-0.005), which was abolished by indomethacin pretreatment. A single instillation of travoprost or unoprostone and 7-day instillation of unoprostone showed no effect.

CONCLUSIONS

After a 7-day instillation in normal rabbit eyes, topical travoprost suppressed ET-1-induced vasoconstrictive effects only in the ipsilateral posterior retina by its local effect; this effect was maintained at least for 30 min and mediated by endogenous prostaglandins.

Short-term effects of topical tafluprost on retinal blood flow in cats

PURPOSE

The aim of this study was to determine the short-term effects of topical tafluprost, a novel prostaglandin F(2) derivative, on feline retinal circulation.

METHODS

Seventeen (17) adult cats were anesthetized with enflurane and mechanically ventilated. One (1) drop of tafluprost (0.0015%; n = 8), latanoprost (0.005%; n = 5), or control vehicle (n = 4) was instilled in 1 eye and the fellow eye was untreated. We measured the intraocular pressure (IOP), vessel diameter, and blood velocity simultaneously for 120 min in the large retinal arterioles and calculated the retinal blood flow (RBF) with a laser Doppler velocimetry system.

RESULTS

Tafluprost 0.0015% significantly increased RBF (maximum change, 42.8 +/- 4.2% [mean +/- standard error of the mean; P < 0.01) and blood velocity (maximum change, 24.1 +/- 3.3%; P < 0.01) for 120 min after instillation; there was no significant change in vessel diameter. Latanoprost 0.005% significantly increased RBF (maximum change, 31.7 +/- 3.4%; P < 0.05); there was no significant change in vessel diameter and blood velocity. There were no significant differences in the IOP reduction among the three groups.

CONCLUSIONS

We observed, for the first time, that topical tafluprost significantly increased RBF in cats, suggesting that dual-action tafluprost may be a beneficial antiglaucomatous agent for reducing IOP and increasing RBF.

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.

The influence of diclofenac ophthalmic solution on the intraocular pressure-lowering effect of topical 0.5% timolol and 0.005% latanoprost in primary open-angle glaucoma patients

The aim of this randomized, prospective, masked clinical study has been to verify the influence of a non-steroidal anti-inflammatory drug ophthalmic solution on intraocular pressure reduction induced by 0.5% timolol and 0.005% latanoprost eyedrops in patients affected by primary open-angle glaucoma. Thirty-two glaucomatous patients, compensated with 0.5% timolol, were randomized into two study groups (A and B). Timolol was continued for the first 2 weeks in all subjects. On the 15th day, in both groups timolol was replaced by latanoprost, and this regimen lasted up to the end of the follow-up (8 weeks). At the beginning of the 2nd week of the study, group A additionally started a 5-week therapy with topical 0.1% diclofenac; during the same period, group B received placebo eyedrops with identical modalities. Intraocular pressure was recorded at 7-day intervals during the first 7 weeks and at the 10th week. Non-steroidal anti-inflammatory drug and placebo did not modify the effect of timolol on intraocular pressure. In both groups, latanoprost induced a significant decrease in intraocular pressure. Diclofenac-treated patients exhibited a marked fall in intraocular pressure (p<0.01), whereas in placebo-treated patients, this diminution was less noticeable (p<0.05). After diclofenac withdrawal, in group A intraocular pressure significantly increased (p<0.01), remaining approximately at the same level up to the end of the study. In group B, at the same checks no significant variations in intraocular pressure occurred. In primary open-angle glaucoma patients, diclofenac significantly enhances the hypotensive effect of latanoprost, without influence on timolol efficacy. Because non-steroidal anti-inflammatory drugs are widely employed in medical practice, supplementary ophthalmologic checks should be scheduled during the co-administration of these compounds and prostaglandin analogues.

A comparison of the effects of dorzolamide/timolol fixed combination versus latanoprost on intraocular pressure and pulsatile ocular blood flow in primary open-angle glaucoma patients

PURPOSE

To evaluate the effects of dorzolamide/timolol fixed combination (D/T) compared to latanoprost on intraocular pressure (IOP) and pulsatile ocular blood flow (POBF) in primary open-angle glaucoma (POAG) patients.

METHODS

Thirty patients with POAG were randomized in an open-label, cross-over study. Intraocular pressure reduction was achieved by 4 weeks medical therapy with D/T twice daily or latanoprost 0.005% dosed once in the evening. During a 4-week run-in and a 4-week wash-out period between study arms, patients ceased use of all other glaucoma medications and used timolol maleate 0.5% twice daily. Primary efficacy variables were IOP and POBF.

RESULTS

There was no difference in baseline IOP and POBF parameters between the two study arms. Both D/T and latanoprost statistically significantly reduced IOP by 4.6 mmHg (p < 0.0001) and 3.75 mmHg (p < 0.0001) and increased POBF by 2.048 microl/second (p = 0.0030) and 2.147 microl/second (p = 0.0009), respectively. Repeated measures anova detected significant changes in POBF with treatment (p = 0.0361). Dorzolamide/timolol fixed combination statistically significantly increased pulse volume by 0.767 microl (p = 0.0087), while latanoprost therapy had no significant effect (p = 0.2407).

CONCLUSIONS

Both drugs had similar effects in terms of IOP reduction. Dorzolamide/timolol significantly increased pulse volume while latanoprost had no effect. Further studies are necessary to establish whether the enhancement of choroidal blood flow can prevent glaucoma progression.

Comparison of the nocturnal effects of once-daily timolol and latanoprost on intraocular pressure

PURPOSE

To compare the nocturnal effects of once-daily timolol and latanoprost on intraocular pressure (IOP) in patients with ocular hypertension or early glaucomatous changes.

DESIGN

Prospective, open-label, experimental study with crossover design.

METHODS

Eighteen patients with ocular hypertension or early glaucomatous changes (aged 41 to 79 years) each received topical treatments with timolol (0.5% Timoptic-XE), latanoprost (0.005% Xalatan), and no IOP-lowering medication, for at least 4 weeks. Timolol was given once in the morning upon awakening and latanoprost once in the evening at bedtime. At the end of each treatment period, the patient was housed in a sleep laboratory for 24 hours and IOP was measured every 2 hours using a pneumatonometer. Measurements were taken sitting and supine during the 16-hour diurnal/wake period and only supine during the 8-hour nocturnal/sleep period. Mean diurnal and nocturnal IOP levels were compared among the treatments with timolol, latanoprost, and no medication.

RESULTS

In the diurnal period, the mean IOP under the timolol or the latanoprost treatment was significantly less than the mean IOP under no medication in both the sitting and the supine positions. There was no statistical difference between the timolol and latanoprost treatments. In the nocturnal period, supine IOP with timolol treatment was not different from the supine IOP with no medication but was significantly higher than supine IOP with the latanoprost treatment.

CONCLUSION

Although both once-daily timolol and latanoprost were effective in lowering IOP during the diurnal period, only latanoprost reduced IOP during the nocturnal period.

Latanoprost : an update of its use in glaucoma and ocular hypertension

Latanoprost (Xalatan) is an ester analogue of prostaglandin F2alpha that reduces intraocular pressure (IOP) by increasing uveoscleral outflow. The IOP-lowering efficacy of latanoprost 0.005% lasts for up to 24 hours after a single topical dose, which allows for a once-daily dosage regimen. In patients with ocular hypertension or open-angle glaucoma, a single drop of latanoprost 0.005% solution (about 1.5 microg) administered topically once daily reduced diurnal IOP by 22 to 39% over 1 to 12 months' treatment in well-controlled trials; efficacy was maintained during treatment periods of up to 2 years. At this dosage, latanoprost was significantly more effective than timolol 0.5% twice daily in 3 of 4 large, double-blind, randomised studies, was generally as effective as bimatoprost or travoprost, and was significantly more effective than dorzolamide, brimonidine or unoprostone. Furthermore, in patients whose IOP was poorly controlled with timolol, switching to latanoprost monotherapy was at least as effective at lowering IOP as adding dorzolamide or pilocarpine to the regimen. Latanoprost has also shown significant additive effects when used in combination with one or more other glaucoma medications. The fixed combination of latanoprost plus timolol was significantly more effective than either of its individual components in two double-blind randomised studies and more effective than the fixed combination of dorzolamide and timolol in a 3-month, evaluator-masked study. Data in patients with angle-closure glaucoma are limited, but in patients with elevated IOP after undergoing iridotomy, latanoprost 0.005% once daily was significantly more effective than timolol 0.5% twice daily at reducing IOP over 12 weeks of treatment in a large double-blind, randomised study. Latanoprost is generally well tolerated and, unlike timolol, induces minimal systemic adverse events. In well-controlled, 6-month trials, the most commonly occurring drug-related ocular events in latanoprost recipients were mild to moderate conjunctival hyperaemia (3 to 15%) and iris colour change (2 to 9%); these seldom required patient withdrawal although the latter may be permanent. Latanoprost 0.005% as a single daily drop has shown good IOP-lowering efficacy in patients with open-angle glaucoma or ocular hypertension and does not produce the cardiopulmonary adverse effects associated with beta-blockers. Thus, latanoprost is a valuable addition to the first-line treatment options for patients with open-angle glaucoma or ocular hypertension. In addition, adjunctive treatment with latanoprost in patients who are refractory to beta-blocker therapy is a viable, second-line treatment option. Although preliminary findings are promising, wider clinical experience is required to define the place of latanoprost in the treatment of angle-closure glaucoma.

Sustained perimacular vascular and visual response to topical beta blockers in normal human eyes

PURPOSE

To assess visual and circulatory responses to treatment with topical beta adrenergic antagonists.

DESIGN

Institutional prospective randomized clinical trial in normal adults.

METHODS

Twenty adults (36 (mean) +/- 8 (S.D.) years) underwent repeated baseline perimetry (Humphrey 30-2), contrast sensitivity (Vector Vision), perimacular microcirculatory studies (Oculix blue-field entoptic simulator), intraocular pressure (IOP), heart rate (HR), and blood pressure (BP) testing. Subjects commenced either timolol 0.5% or betaxolol 0.5% twice daily on day 1, were retested on days 3 and 35, discontinued treatment for 21 days, whereupon repeated tests were performed. Treatment responses were compared by paired t-test.

RESULTS

Timolol-treated eyes showed improvement in contrast sensitivity (P=0.03) and pericentral perimetric thresholds (P=0.01), but corresponding increases among betaxolol-treated eyes were significantly higher (P=0.03 and 0.04, respectively, relative to timolol-treated eyes). Leukocyte velocity increased with both drugs, each with post-withdrawal carryover (P< or =0.03). Significant IOP reduction (approximately 2.5 mmHg) occurred in both groups, BP fell 2.8 mmHg among betaxolol-treated subjects (P=0.02), and HR was 2 bpm slower among timolol-treated subjects (P=0.03), but all reverted to baseline values after washout.

CONCLUSIONS

Both treatment groups demonstrated significant changes in visual function and perimacular hemodynamics, sustained after the terminal 3-week washout period.

The effects of antiglaucoma and systemic medications on ocular blood flow

Based on the body of evidence implicating ocular blood flow disturbances in the pathogenesis of glaucoma, there is great interest in the investigation of the effects of antiglaucoma drugs and systemic medications on the various ocular vascular beds. The primary aim of this article was to review the current data available on the effects of antiglaucoma drugs and systemic medications on ocular blood flow. We performed a literature search in November 2002, which consisted of a textword search in MEDLINE for the years 1968-2002. The results of this review suggest that there is a severe lack of well-designed long-term studies investigating the effects of antiglaucoma and systemic medications on ocular blood flow in glaucomatous patients. However, among the 136 articles dealing with the effect of antiglaucoma drugs on ocular blood flow, only 36 (26.5%) investigated the effects of medications on glaucoma patients. Among these 36 articles, only 3 (8.3%) were long-term studies, and only 16 (44.4%) were double-masked, randomized, prospective trials. Among the 33 articles describing the effects of systemic medications on ocular blood flow, only 11 (33.3%) investigated glaucoma patients, of which only one (9.1%) was a double-masked, randomized, prospective trial. Based on this preliminary data, we would intimate that few antiglaucoma medications have the potential to directly improve ocular blood flow. Unoprostone appears to have a reproducible antiendothelin-1 effect, betaxolol may exert a calcium-channel blocker action, apraclonidine consistently leads to anterior segment vasoconstriction, and carbonic anhydrase inhibitors seem to accelerate the retinal circulation. Longitudinal, prospective, randomized trials are needed to investigate the effects of vasoactive substances with no hypotensive effect on the progression of glaucoma.

Evaluating pulsatile ocular blood flow analysis in normal and treated glaucomatous eyes

PURPOSE

To evaluate pulsatile ocular blood flow (POBF) analysis in normal subjects and glaucoma patients by comparison of POBF measurements with functional (as determined by visual field [VF]) and structural (as determined by optical coherence tomography [OCT]) measures.

DESIGN

Prospective, cross-sectional study.

METHODS

Forty-one eyes of 24 consecutive glaucoma patients and 20 eyes of 10 healthy subjects were studied; POBF analysis was performed on all subjects at the same visit as VF testing and OCT retinal nerve fiber layer (NFL) thickness measurement. The mean results of normal and glaucomatous eyes were compared for each method. Correlation between measurements obtained with each modality and the discriminating power using receiver operator characteristic curves was tested.

RESULTS

The mean POBF (standard deviation [SD]) in the normal group was 1,010.4 (292.8) microl/min and 989.3 (305.5) microl/min in the glaucoma group (P =.90). Significant differences between groups were found for VF mean deviation and pattern standard deviation (P =.02, P =.004, respectively) and OCT mean NFL thickness (P <.0001). No correlation was found between POBF parameters and intraocular pressure, VF, or OCT variables except for intraocular pressure in glaucoma group (r = -.43, P =.003). The area under the receiver operator characteristic curves was higher for VF indexes and OCT mean NFL thickness than POBF parameters for distinguishing between normal and glaucomatous eyes.

CONCLUSIONS

The wide range of normal values and the low discriminating power of POBF between normal and glaucomatous eyes limits the clinical use of the device for glaucoma patients.

Comparative analysis of the effects of dorzolamide and latanoprost on ocular hemodynamics in normal tension glaucoma patients

PURPOSE

To compare the effects of latanoprost (Xalatan) and dorzolamide (Trusopt) on ocular hemodynamics in normal-tension glaucoma patients.

METHODS

A randomized, single-masked, parallel design study was conducted. After a 4-week washout period, 20 normal tension glaucoma patients, recruited from a single university-based ophthalmology clinic, received either latanoprost once daily or dorzolamide 3 times daily for 4 weeks. The subjects were examined at baseline and post-treatment. Outcome measures included heart rate (HR), blood pressure (BP), logMar visual acuity (VA), contrast sensitivity (CS), intraocular pressure (IOP), color Doppler imaging (CDI), and fluorescein angiography with the Rodenstock scanning laser ophthalmoscope (SLO). CDI measurements of the retrobulbar vessels included peak systolic velocity, end diastolic velocity, and the calculated resistance index. Arterio-venous passage time (AVP) in the superior and inferior temporal retina was calculated from the SLO angiograms.

RESULTS

Neither dorzolamide nor latanoprost had any statistically significantly effect on HR or BP. Both drugs significantly lowered IOP without altering calculated ocular perfusion pressure (p<0.05). There was no statistically significant difference in any CDI measurement. Dorzolamide significantly decreased AVP time in the superior retina (p=0.011), while latanoprost did not (p=0.62).

CONCLUSIONS

Dorzolamide, unlike latanoprost, significantly reduced AVP times in the superior temporal retina in normal tension glaucoma (NTG) patients.

Effect of different dose schedules of bimatoprost on intraocular pressure and pupil size in the glaucomatous Beagle

The changes in intraocular pressure and pupil size in glaucomatous dogs were evaluated after instillations of 0.03% bimatoprost (Lumigan, Allergan, Irvine, CA USA) once in the morning, or once in the evening, or twice daily in five day multiple dose studies. Applanation tonometry (IOP) and pupil size (PS) measurements were obtained at 8 am, 10 am, 12 noon, 2 pm, and 4 pm in 8 glaucoma dogs. Methylcellulose (0.5% as placebo) was instilled in the control eye, and 0.03% bimatoprost was instilled in the opposite drug eye. Methylcellulose (0.5%) and 0.03% bimatoprost were instilled the second through the fifth days with instillations in the morning (8:30 am), or evening (8 pm), or twice daily (8:30 am and 8 pm). The mean +/- SEM diurnal changes in IOP from baseline values after 0.03% bimatoprost at 8 am once daily for the next four days were 25.0 +/- 3.2 mm Hg, 25.6 +/- 2.9 mm Hg, 25.5 +/- 3.0 mm Hg, and 26.0 +/- 3.2 mm Hg respectively, and were significantly different from the control eye. After bimatoprost was instilled at 8 pm, the mean +/- SEM changes in IOP from baseline values in the drug eyes were 27.3 +/- 2.4 mm Hg, 26.6 +/- 2.2 mm Hg, 27.2 +/- 2.5 mm Hg, and 27.3 +/- 2.6 mm Hg respectively. When 0.03% bimatoprost was instilled twice daily, the mean +/- SEM changes in IOP from baseline values were 39.1 +/- 2.3 mm Hg, 39.9 +/- 2.2 mm Hg, 39.9 +/- 2.3 mm Hg, and 39.6 +/- 2.1 mm Hg respectively, and were significantly different from the control eyes. Miosis of varying duration was frequent during the three studies. Bimatoprost instilled once daily (am or pm) as well as twice daily produces significant decreases in IOP and PS in the glaucomatous Beagle.

Changes in intraocular pressure and ocular perfusion pressure after latanoprost 0.005% or brimonidine tartrate 0.2% in normal-tension glaucoma patients

OBJECTIVE

To evaluate and compare the effects of latanoprost 0.005% once daily and brimonidine tartrate 0.2% twice daily in patients with normal-tension glaucoma (NTG).

DESIGN

A randomized, open-label, crossover study.

PARTICIPANTS

Twenty-eight NTG patients with progressive visual field defects/optic disc excavation, new disc hemorrhage, or field defects that threatened fixation.

INTERVENTION

Patients were randomly allocated to one of two groups. Patients in group 1 were treated with latanoprost, lubricant, and brimonidine for 4 weeks each, whereas patients in group 2 were treated with brimonidine, lubricant, and latanoprost for 4 weeks each.

MAIN OUTCOME MEASURES

Intraocular pressure (IOP), pulse rate, and blood pressure were measured at 8 am, 12 noon, and 4 pm after each 4-week treatment. Ocular perfusion pressure (OPP) was calculated.

RESULTS

Latanoprost and brimonidine reduced the average IOP by 3.6 +/- 1.9 mmHg (P < 0.001) and 2.5 +/- 1.3 mmHg (P < 0.001), respectively, with a significant difference between the two regimens (P = 0.009). Both drugs significantly reduced IOP at each time point. Latanoprost decreased IOP significantly more than did brimonidine at 8 am (11.7 +/- 2.2 mmHg vs. 13.7 +/- 2.1 mmHg, P = 0.004) and 4 pm (11.4 +/- 2.1 mmHg vs. 13.2 +/- 2.9 mmHg, P = 0.004), but IOP was equal between the two agents at 12 noon (11.5 +/- 2.6 mmHg vs. 11.5 +/- 2.3 mmHg, P = 0.967). IOP was maintained at 12 mmHg or lower in 18 (66.7%) of 27 patients after treatment with latanoprost and in 9 (33.3%) of 27 patients after treatment with brimonidine. Latanoprost monotherapy reduced IOP by 30% in 8 patients (29.6%), but brimonidine monotherapy did not reduce IOP by that much in any of the patients. OPP increased after latanoprost treatment (P < 0.001) but did not increase after brimonidine treatment (P = 0.355). There was no significant change in pulse rate or blood pressure.

CONCLUSIONS

Both latanoprost and brimonidine reduce IOP in NTG patients. Brimonidine has a peak IOP-lowering effect equal to that of latanoprost but produces a higher mean diurnal IOP than does latanoprost because of its shorter effect. Latanoprost might favorably alter optic disc blood perfusion by increasing OPP.

Effect of latanoprost 0.005% and brimonidine tartrate 0.2% on pulsatile ocular blood flow in normal tension glaucoma

AIM

To determine the effect of brimonidine tartrate 0.2% and latanoprost 0.005% on pulsatile ocular blood flow (POBF) in patients with normal tension glaucoma (NTG).

METHOD

NTG patients with progressive optic neuropathy, new disc haemorrhage, or field defects that threatened fixation were enrolled into a randomised, investigator masked, crossover study. Group I patients received 4 weeks each of latanoprost, lubricant, and brimonidine, while group II patients received 4 weeks each of brimonidine, lubricant, and latanoprost. Diurnal POBF was measured at baseline and after each 4 week treatment.

RESULTS

25 patients completed the study and had reliable POBF measurement at each visit. There was no significant diurnal change in baseline POBF (p = 0.768). Latanoprost increased POBF by 213 (SD 257) micro l/min (22.8%, p <0.001) while brimonidine increased it by 97 (183) micro l/min (10.4%, p = 0.014). POBF increased at 8 am (p = 0.004), 12 noon (p = 0.002), and 4 pm (p <0.001) with latanoprost, while it increased only at 8 am (p = 0.016) with brimonidine. After adjusting for the factor of IOP, neither latanoprost nor brimonidine increased POBF significantly.

CONCLUSIONS

Latanoprost increases the mean POBF that is related to its IOP lowering effect. The increase in POBF noted after brimonidine is within the range of long term variation and may not be attributable to the drug effect.

Comparative effects of latanoprost (Xalatan) and unoprostone (Rescula) in patients with open-angle glaucoma and suspected glaucoma

PURPOSE

To compare, in paired eyes of open-angle glaucoma patients and glaucoma suspects, hydrodynamic and visual changes after 1 month of topical latanoprost in one eye and unoprostone in the other.

DESIGN

Single-center, institutional randomized clinical trial.

METHODS

After completing a washout period off all topical medication, 25 adults (mean age 54 +/- SEM 2 years) with bilateral open-angle glaucoma or glaucoma suspect status underwent morning (8 to 10 AM) and afternoon (1 to 3 PM) measurements of intraocular pressure (IOP), pulsatile ocular blood flow (POBF), contrast, sensitivity, frequency doubling technology, and Humphrey 10-2 perimetry (HVFA II) in both eyes. Each then started unoprostone 0.15% (Rescula) in one randomly assigned eye and latanoprost 0.005% (Xalatan) in the other. Unoprostone was administered at 8 AM and 8 PM and latanoprost at 8 PM with placebo at 8 AM, both from masked bottles. After 28 days, differences were determined for each measured variable by two-tailed paired t test.

RESULTS

Starting from similar baseline IOP levels, after 1 month of treatment, the mean morning IOP values differed according to the topical agent received (16.2 +/- SEM 0.6 mm Hg for latanoprost vs 17.9 +/- 0.7 mm Hg for unoprostone; P =.001). These morning pressures were 2.6 mm Hg lower than baseline in the eyes receiving latanoprost (P <.0001), and 1.6 mm Hg lower in unoprostone-treated eyes (P =.02). Afternoon values were 3.1 +/- SEM 0.6 lower than corresponding baseline in eyes receiving latanoprost, and 2.4 +/- SEM 0.6 mm Hg in unoprostone-treated eyes (P <.0001 from baseline for both medications; interdrug mean IOP difference; P =.04). Eyes receiving unoprostone showed a 1.7-db improvement in frequency doubling mean deviation (P =.03), the only significant visual function change observed. Pulsatile ocular blood flow increased 30% relative to baseline in eyes receiving latanoprost, (P <.0001) and 16% in eyes receiving unoprostone (P =.05) by the morning of day 28. That afternoon, mean POBF had increased 30% (P <.0001) relative to afternoon baseline values among eyes receiving latanoprost and 18% (P =.03) among those receiving unoprostone (interdrug change difference, P =.05). Humphrey perimetry and contrast sensitivity remained stable with both prostanoids.

CONCLUSIONS

Both latanoprost and unoprostone produced significant reductions in IOP and increases in POBF, with stable central and perimacular visual function. Latanoprost once daily produced IOP reduction and POBF increases nearly twofold greater than those obtained with unoprostone twice daily. These differences in IOP and POBF change between unoprostone and latanoprost were statistically significant.

Latanoprost and brimonidine: therapeutic and physiologic assessment before and after oral nonsteroidal anti-inflammatory therapy

PURPOSE

To assess, before and during oral nonsteroidal anti-inflammatory drug coadministration, latanoprost's and brimonidine's hypotensive action in eyes at risk of glaucomatous progression, assessing the effect of each drug on ocular perfusion and visual function.

METHODS

Twenty consenting adults with open-angle glaucoma or ocular hypertension underwent a double-masked, bilateral, randomized prospective study. Treatment started with either latanoprost 0.005% in the morning and placebo in the evening, or brimonidine 0.2% twice daily in one eye; after 1 week starting the other in the fellow eye. After another week, oral indomethacin 25 mg four times a day, commenced for 2 more weeks. Intraocular pressure, ocular circulation, and visual function were monitored pretreatment, after unilateral monotherapy (day 7), bilateral ocular therapy (day 14), and coadministered oral indomethacin (day 28). Intrasubject differences (interocular and intraocular relative to baseline) were determined by two-tailed paired t test.

RESULTS

A loss of the significance of intraocular pressure reduction with brimonidine was noted after oral indomethacin coadministration (-14%; P =.004 for brimonidine alone versus -11%; P =.3 with indomethacin). Significant intraocular pressure reduction with latanoprost persisted despite indomethacin (-25%; P <.0001 for latanoprost alone versus -30%; P <.0001 with indomethacin). Pulsatile ocular blood flow increased 40% with latanoprost, but was unchanged with brimonidine (interdrug difference, P =.004). Midperipheral retinal microcirculation increased 23% (P =.03) with latanoprost. Humphrey perimetry and contrast sensitivity remained consistently at or above baseline with both latanoprost and brimonidine. Indomethacin had no significant effect on ocular perfusion or visual function measures.

CONCLUSIONS

Circulatory and hydrodynamic findings differed substantially for the two drugs. The loss of significance of intraocular pressure reduction with brimonidine during indomethacin treatment may be clinically important.

Effect of different dose schedules of latanoprost on intraocular pressure and pupil size in the glaucomatous Beagle

OBJECTIVE

To evaluate the changes in intraocular pressure and pupil size in glaucomatous dogs after instillation of 0.005% latanoprost (Xalatan, Pharmacia and Upjohn, Kalamazoo, MI, USA) once in the morning, or once in the evening, or twice daily in five-day multiple-dose studies. Animals studied Eight Beagles with the moderate stage of inherited primary open-angle glaucoma.

PROCEDURES

Applanation tonometry (IOP) and pupil size (PS) measurements were obtained at 8 am, 10 am, 12 noon, 2 pm, and 4 pm in eight glaucoma dogs. Methylcellulose (0.5% as placebo) was instilled in the control eye, and 0.005% latanoprost was instilled in the opposite drug eye. Control and drug eyes were selected using a random table. For these three studies, 0.5% methylcellulose and 0.005% latanoprost were instilled the second through the fifth days with instillations in the morning (8.30 am), or evening (8 pm), or twice daily (8.30 am and 8 pm). Statistical comparisons between drug groups included control, placebo, and treated (0.005% latanoprost) eyes for three multiple-dose studies.

RESULTS

In the 8-am latanoprost study, the mean +/- SEM diurnal declines in IOP for the placebo and drug eyes for the first day were 6.5 +/- 3.6 mmHg and 8.4 +/- 4.0 mmHg, respectively. The mean +/- SEM diurnal changes in IOP after 0.005% latanoprost at 8 am once daily for the next four days were 23.3 +/- 5.0 mmHg, 25.4 +/- 2.1 mmHg, 25.7 +/- 1.7 mmHg, and 26.1 +/- 1.7 mmHg, respectively, and were significantly different from the control eye. A significant miosis also occurred starting 2 h postdrug instillation, and the resultant mean +/- SD pupil size was 1.0 +/- 0.1 mm. In the first day of the second latanoprost study, the mean +/- SEM diurnal changes in the placebo and drug eye IOPs were 11.6 +/- 3.8 mmHg, and 12.0 +/- 4.4 mmHg, respectively. For the following four days with latanoprost instilled at 8 pm, the mean +/- SEM diurnal changes in IOP in the drug eyes were 24.9 +/- 2.1 mmHg, 22.4 +/- 1.8 mmHg, 21.6 +/- 1.9 mmHg, and 26.6 +/- 2.2 mmHg, respectively. Compared to the fellow placebo eyes, the diurnal changes in IOP were significantly different. Significant changes in pupil size were similar to the IOP changes, with miosis throughout the day and return to baseline pupil size the following morning before drug instillation. In the last study, the mean +/- SEM diurnal changes in IOP for the placebo and drug eyes for the first day were 6.6 +/- 2.1 mmHg and 9.4 +/- 2.8 mmHg, respectively. For the four subsequent days with latanoprost instilled twice daily, the mean +/- SEM diurnal IOP changes were 19.6 +/- 1.5 mmHg, 19.1 +/- 1.4 mmHg, 19.9 +/- 1.7 mmHg, and 20.3 +/- 0.7 mmHg, respectively, and were significantly different from the placebo eyes. The mean changes in PS were 3.1 +/- 0.7 mm.

CONCLUSION

0.005% latanoprost instilled once daily (am or pm) as well as twice daily produces significant decreases in IOP and PS in the glaucomatous Beagle. The evening instillation of 0.005% latanoprost produced less daily fluctuations in IOP than when the drug was instilled in the morning. 0.005% latanoprost instilled twice daily produced the greatest decline in IOP with the least daily fluctuations, but longer duration miosis.

The impact of glaucoma medication on parameters of ocular perfusion

Whereas intraocular pressure is considered a major risk factor in glaucoma, growing evidence now indicates that ocular ischemia plays a major role too. By virtue of this and because many existing medications are able to interact with vasculature, altering ocular blood flow, it is essential that current and future medications for glaucoma be evaluated for their effect on ocular circulation. The authors review published papers examining the effect of topical and some systemic medications on ocular blood flow, focusing mostly on data from the human eye. The authors provide a comprehensive review on the effect of subclasses of medications (eg, carbonic anhydrase inhibitors, beta-blockers, alpha-adrenergic agonists, and prostaglandin analogues on optic nerve head, and on retinal, choroidal, and retrobulbar circulation. The various claims for enhancements or reduction of ocular circulation within each class of medication are reviewed and evaluated.