A double-masked, randomized clinical trial comparing latanoprost with unoprostone in patients with open-angle glaucoma or ocular hypertension

Omidenepag, a non-prostanoid EP2 receptor agonist, induces enlargement of the 3D organoid of 3T3-L1 cells

2D and 3D cultures of 3T3-L1 cells were employed in a study of the effects of Omidenepag (OMD), interacting with a non-prostanoid EP2 receptor, on adipogenesis. Upon adipogenesis, the effects on lipid staining, the mRNA expression of adipogenesis-related genes (Pparγ, CEBPa, Ap2, and Glut4) and the extracellular matrix (ECM) including collagen type 1, 4 and 6, and fibronectin, and the size and physical property of 3D organoids were compared between groups that had been treated with EP2 agonists (butaprost and OMD) and PGF2α. Upon adipogenesis, these significantly suppressed lipid staining and the mRNA expression of related genes. EP2 agonists and PGF2α influenced the mRNA expression of ECM in different manners, and these effects were also different between 2 and 3D cultures. Examining the physical properties by a microsqueezer indicated that the solidity of the 3D organoids became significantly lowered upon adipogenesis and these effects were not affected by EP2 agonists. In contrast, 3D organoid stiffness was markedly enhanced by the presence of PGF2α. These observations indicate that EP2 agonists affect the adipogenesis of 3T3-L1 cells in different manners, as compared to PGF2α, suggesting that OMD may not induce PGF2α related orbital fat atrophy, called the deepening of the upper eyelid sulcus (DUES).

Effect of prostaglandin analogs: Latanoprost, bimatoprost, and unoprostone on matrix metalloproteinases and their inhibitors in human trabecular meshwork endothelial cells

Bimatoprost, latanoprost, and unoprostone are prostaglandin F_2α analogs (PGAs) and are used to lower intraocular pressure. We investigated the free acid effects of these three prostaglandin analogs: bimatoprost, latanoprost, and unoprostone on human matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMP) in the trabecular meshwork (TM) cells. Immunoblot results show that all three PGAs generally increased MMPs-1,9 and TIMPs-4. Additionally, bimatoprost and latanoprost both increased MMP-3 and TIMP-2, while unoprostone had an indeterminate effect on both. Zymography results show that all three PGAs except unoprostone increased intermediate MMP-1 activity while bimatoprost and latanoprost increased MMP-9 activity. Together, these data suggest that the balance between MMPs and TIMPs correlate to the relative intraocular pressure lowering effectiveness observed in clinical studies of these PGAs.

Acceptability, adherence and economic analyses of a new clinical pathway for the identification of non-responders to glaucoma eye drops: a prospective observational study

BACKGROUND/AIMS

Assess whether a new clinical pathway for glaucoma was acceptable to patients and healthcare professionals and whether it provided useful clinical information on non-responsiveness and non-adherence to the treatment of elevated intraocular pressure with latanoprost eye drops.

METHODS

A single arm non-randomised prospective observational study incorporating new glaucoma/ocular hypertension patients. To assess issues of acceptability, qualitative observation and interviews were conducted with patients and healthcare professionals. To determine clinical responsiveness, intraocular pressures were measured before and 4 hours after a clinician-instilled eye drop over two distinct appointments. Adherence data were collected using a Medicine Event Monitoring System. Economic analyses compared the costs between novel and standard care pathways.

RESULTS

Of 72 patients approached, 53 entered the study (74.3%) and 50 completed all procedures (94.3%). Intraocular pressure was reduced more than 15% in 83 out of 92 study eyes by final visit (90.2%). The non-response rate was 5.1% once the effect of low adherence was minimised. For the 1376 drop instillation days under observation, eye drops were instilled as prescribed on 1004 days (73.0%), over-instilled on 137 days (9.9%) and not instilled on 235 days (17.1%). The Cardiff Model of Glaucoma Care involved negligible cost, although acceptance for healthcare professionals showed variation.

CONCLUSIONS

The Cardiff Model of Glaucoma Care offers novel clinical and adherence insights at marginal costs while acceptable to patients. Healthcare professionals felt that 4 hour and 4 week follow-up appointments could cause administrative problems. A streamlined version of the pathway has therefore been developed to facilitate clinical adoption.

TRIAL REGISTRATION NUMBER

ISRCTNID:ISRCTN75888393.

Intraocular Pressure Lowering Effect of Latanoprost as First-line Treatment for Glaucoma

PURPOSE

The purpose of this study was to assess the intraocular pressure (IOP) - reducing effect of latanoprost in treatment-naïve patients with newly detected open-angle glaucoma with no restriction of the level of untreated IOP.

METHODS

Eighty-six patients (105 eyes) with a diagnosis of open-angle glaucoma received IOP-lowering therapy with latanoprost. The IOP reduction 1 and 3 months after initiation of treatment was recorded.

RESULTS

Mean untreated IOP for all eyes was 26.2 mm Hg (ranging from 10 to 51 mm Hg). The mean pressure reduction was 7.9 mm Hg (28%), with equivalent average levels at 1 and 3 months. The reduction in IOP ranged from -2.3 to 25.3 mm Hg after 1 month, and from -1.3 to 33.3 mm Hg after 3 months. The pressure-lowering effect was considerably more pronounced in eyes with higher untreated IOP; the reduction increased by 0.55 mm Hg per mm Hg higher untreated IOP. Four eyes, with untreated IOP within statistically normal limits, had no or negative IOP-reduction. A regression model predicted that IOP reduction ended at untreated IOP≤16 mm Hg. Multiple regression analysis showed that an additional IOP-lowering effect of 1.28 mm Hg was achieved in eyes with pseudoexfoliation glaucoma.

CONCLUSIONS

To the best of our knowledge, this paper is the first to report the IOP-reducing effect of latanoprost treatment at all untreated IOP levels in newly detected glaucoma patients. The effect was proportional to the untreated IOP at all levels above 16 mm Hg and better at higher untreated IOP levels, also in relative terms. Our results further confirm the indication of latanoprost as a first-line therapy for glaucoma.

Intraocular Pressure, Safety and Quality of Life in Glaucoma Patients Switching to Latanoprost from Adjunctive and Monotherapy Treatments

Purpose

To evaluate efficacy, safety and quality of life in ocular hypertensive or open-angle glaucoma patients changed to latanoprost from previous therapy.

Methods

A prospective, multicenter, active-controlled design in which qualified patients had their previous therapy substituted for latanoprost and were followed for at least thee months.

Results

In 1068 patients, latanoprost was continued 92% throughout the 36-month observation period. Latanoprost treatment reduced the intraocular pressure (IOP)(p < 0.001) when compared to previous monotherapies including: beta-blockers (-4.0 ± 3.7 mmHg, 42%), alpha-antagonists (-3.9 ± 3.0 mmHg, 14%), miotics (-3.8 ± 3.5 mmHg, 2%), or carbonic anhydrase inhibitors (CAI) (-3.8 ± 3.6 mmHg, n = 16%), and adjunctive therapy including: beta-blocker and CAI (-3.7 ± 3.1 mmHg, n = 12%), alpha-agonist (-3.7 ± 3.4 mmHg, n = 5%), or pilocarpine (-3.4 ± 3.7 mmHg, n = 6%), or CAI and alpha-agonist (-4.6 ± 6.4 mm Hg, n = 2%)(p < 0.0017). The most common adverse event with latanoprost was ocular allergy (1.5% incidence). Patients showed a preference for latanoprost for many systemic and ocular quality of life measures on a non-validated questionnaire (p < 0.05).

Conclusions

In a clinical setting, patients who have their mono- and adjunctive therapy treatment substituted for latanoprost may on average experience reduced IOP, deceased side effects and increased quality of life measures.

Association between SNPs of Metalloproteinases and Prostaglandin F2α Receptor Genes and Latanoprost Response in Open-Angle Glaucoma

PURPOSE

To determine whether single nucleotide polymorphisms (SNPs) of genes coding for matrix metalloproteinases (MMPs) and the prostaglandin F2α receptor gene (PTGFR) are related to a response to latanoprost in a white Spanish population of glaucomatous patients.

DESIGN

Case-control study.

PARTICIPANTS

One hundred twenty-four patients with open-angle glaucoma.

METHODS

Genotyping was performed in 117 patients with primary open-angle glaucoma with a minimum treatment duration of 4 weeks. Candidate genes and individual polymorphisms were selected according to the effect on the mechanism of action of latanoprost. Multi-SNP haplotype analyses for associations also were tested.

MAIN OUTCOME MEASURES

Diurnal intraocular pressure reduction and genotyping of the SNPs in the MMPs and PTGFR.

RESULTS

The PTGFR SNPs were associated with positive (rs6686438, rs10786455) and negative (rs3753380, rs6672484, rs11578155) responses to latanoprost. Multiple testing found 2 genes, PTGFR and MMP-1, were related to refractoriness to latanoprost.

CONCLUSIONS

The SNPs of the PTGFR and MMP-1 genes may determine the latanoprost response in a white European Spanish population. This study identified 5 SNPs related to the latanoprost response; 1 SNP, rs3753380, already has been associated with a poor response to latanoprost in a healthy Japanese population. Latanoprost is a commonly used antiglaucomatous drug, and increased knowledge of its mechanism of action will lead to advances in pharmacogenetics.

An evidence-based review of unoprostone isopropyl ophthalmic solution 0.15% for glaucoma: place in therapy

Glaucoma is a progressive, neurodegenerative optic nerve disease that can cause significant visual morbidity and affects over 60 million people worldwide. The only known modifiable risk factor for glaucoma at this time is elevated intraocular pressure (IOP), which may be treated with medications, laser therapy, and/or incisional surgery. Topical ocular medications are commonly used as first-line therapy for glaucoma, although side effects may limit their use. Unoprostone is a novel 22-carbon ocular hypotensive agent that may be advantageous in treating some patients with open angle glaucoma or ocular hypertension. Unlike the 20-carbon prostanoids, such as latanoprost, that lower IOP primarily through an increase in uveoscleral outflow, unoprostone may lower IOP through increased aqueous outflow via the conventional trabecular meshwork pathway. Although not as efficacious as other prostanoids, unoprostone is effective for IOP reduction both as monotherapy and adjunctive therapy with timolol. Unoprostone has decreased affinity for the prostaglandin F2α receptor, which may explain its well tolerated ocular and systemic side effect profile compared with other prostanoids.

Prostanoid receptor EP2 as a therapeutic target

Cycoloxygenase-2 (COX-2) induction is prevalent in a variety of (brain and peripheral) injury models where COX-2 levels correlate with disease progression. Thus, COX-2 has been widely explored for anti-inflammatory therapy with COX-2 inhibitors, which proved to be effective in reducing the pain and inflammation in patients with arthritis and menstrual cramps, but they have not provided any benefit to patients with chronic inflammatory neurodegenerative disease. Recently, two COX-2 drugs, rofecoxib and valdecoxib, were withdrawn from the United States market due to cardiovascular side effects. Thus, future anti-inflammatory therapy could be targeted through a specific prostanoid receptor downstream of COX-2. The PGE2 receptor EP2 is emerging as a pro-inflammatory target in a variety of CNS and peripheral diseases. Here we highlight the latest developments on the role of EP2 in diseases, mechanism of activation, and small molecule discovery targeted either to enhance or to block the function of this receptor.

Clinical options for the reduction of elevated intraocular pressure

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

Evaluation of investigator bias in industry-funded clinical trials of latanoprost

OBJECTIVE

To determine whether sponsorship of prostaglandin analogue (PGA) clinical trials results in investigator bias in outcomes when studying intraocular pressure (IOP).

DESIGN

Retrospective, observational cohort study.

METHODS

A PubMed search was performed for latanoprost or Xalatan, bimatoprost or Lumigan, and travoprost or Travatan, with limits to humans, clinical trials, and English language. Inclusion criteria included randomized controlled trials, open-angle glaucoma, monotherapy with a PGA, baseline IOP ≥ 21 mm Hg, washout period, and minimum 1-month follow-up. Each article was reviewed by 2 independent reviewers. The results of IOP for each PGA were categorized as being sponsored by the parent company (the company manufacturing the PGA); by the competing company (the company manufacturing competing glaucoma therapy); or by a nonindustry source. The mean IOP and changes in IOP from baseline were compared among the 3 categories of sponsorship.

RESULTS

Only studies involving latanoprost were analyzed because of the low number of studies meeting the inclusion criteria for bimatoprost and travoprost. We found 29 and 13 studies that provided 1- and 3-month data, respectively, for analysis. The mean baseline IOPs in the 3 groups (parent company, competing company, nonindustry) were not significantly different (p = 0.47). The mean IOP at 1 (p = 0.72) and 3 months (p = 0.59) and the change in IOP from baseline (p = 0.83 and 0.90, respectively) were not significantly different in the 3 groups. A random-effects metaregression controlling for the covariates of blinding, naïveté to PGAs, and baseline IOP < 24 mm Hg or ≥ 24 mm Hg did not change the findings.

CONCLUSION

There was no evidence of investigator bias in determining outcomes for IOP in these clinical trials of latanoprost.

A review of the use of latanoprost for glaucoma since its launch

INTRODUCTION

Prostaglandins are increasingly used as first choice treatment for glaucoma because they are highly effective, lack relevant systemic side effects and require just once-daily administration. Latanoprost is an ester prodrug analog of prostaglandin F2α, which reduces intraocular pressure (IOP) by increasing uveoscleral outflow. Latanoprost 0.005% has received European and US approval as the first-line drug for reducing IOP in patients with open-angle glaucoma or ocular hypertension. Following the recent patent expiry for Xalatan®, a number of latanoprost generics have entered the glaucoma market.

AREAS COVERED

This review, achieved through PubMed and Medline research methods, describes the composition, pharmacokinetics, mode of action, efficacy, side effects and safety profile of latanoprost.

EXPERT OPINION

Latanoprost was the first prostaglandin analog introduced in glaucoma management and it dramatically changed the market of the disease thanks to its efficacy and safety. Conjunctival hyperemia, which is commonly found after latanoprost use, is associated with a minor efficacy and duration of trabeculectomy; yet, from the ophthalmologist's perspective, this side effect seems largely counterbalanced by the high efficacy and safety of this compound. It is always advisable to consider the pro-inflammatory mode of action of latanoprost because this may have negative effects in particular patients (i.e., those with uveitis and cystoid macular edema) for whom caution and close follow-up is necessary.

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.

Aqueous humor concentrations of bimatoprost free acid, bimatoprost and travoprost free acid in cataract surgical patients administered multiple topical ocular doses of LUMIGAN or TRAVATAN

PURPOSE

To quantify the aqueous humor (AH) concentrations of bimatoprost (amide), travoprost (isopropyl ester), and their hydrolysis products, bimatoprost free acid (BFA) and travoprost free acid (TFA), after multiple topical ocular doses of LUMIGAN and TRAVATAN, respectively, in patients awaiting cataract surgery.

METHODS

In 2 separate open-label, sparse-sampling trials, glaucoma patients with cataracts received LUMIGAN (bimatoprost ophthalmic solution, 0.03%) or TRAVATAN (travoprost ophthalmic solution, 0.004%) bilaterally once daily for at least 21 days prior to cataract surgery. Anterior chamber paracentesis was performed at selected times up to 5 h after the last dose and an AH sample was collected. AH samples were assayed by an independent bioanalytical laboratory using a sensitive and validated tandem LC-MS/MS method. The assay lower limits of quantitation were 0.59 nM for bimatoprost, 0.29 nM for BFA, and 0.44 nM for TFA.

RESULTS

AH concentrations of BFA (17-phenyl-trinor PGF(2alpha)) were quantifiable in all but one sample at 0.5 h. The maximum concentration achieved (C(max)) of BFA was 30.9 + or - 16.41 nM (n =5), observed at 2 h postdose. AH concentrations of bimatoprost amide were lower than BFA at all time points, with a C(max) of 6.81 + or - 1.36 nM (n = 7) at 1 h postdose. For TFA, measurable AH concentrations were obtained at all time points with a TFA C(max) of 3.91 + or - 2.27 nM (n = 5), which was observed at 3 h after the dose (all data are mean + or - SEM).

CONCLUSIONS

Once daily topical ocular administration of LUMIGAN or TRAVATAN for 3 weeks resulted in significant concentrations of BFA and TFA in the AH. Quantifiable levels of bimatoprost amide were also measured. Maximum concentrations of BFA (30.9 nM) and TFA (3.91 nM) in the anterior chamber are sufficient to fully activate the FP prostanoid receptors in the target cells of the ciliary muscle and trabecular meshwork. Both bimatoprost in LUMIGAN and travoprost in TRAVATAN are essentially prodrugs that are rapidly hydrolyzed to their respective free acids that induce the IOP-lowering effect observed with both drugs in vivo.

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.

Unoprostone isopropyl rescues retinal progenitor cells from apoptosisin vitro

PURPOSE

Unoprostone isopropyl is an ocular hypotensive that was originally produced as a prostaglandin F2alpha analogue and is eventually recognized as a synthetic docosanoid. The compound is recently suggested to have potent neuroprotective ability in the retina. The purpose of this study is to test whether and how the biologically active metabolites of unoprostone isopropyl rescue retinal neuro-glial progenitor cells from apoptosis.

METHODS

R28 cells were deprived of serum for 24 hr with or without varying concentrations of unoprostone metabolite M1 or M2 or vehicle in the presence or absence of specific inhibitors against several types of signal transduction proteins. Immunocytochemistry against activated caspase-3 with Hoechst nuclear staining was performed.

RESULTS

Up to 15%of R28 cells became pyknotic and activated caspase-3 immunoreactive after 24-hr serum withdrawal. M1, but not M2, significantly reduced apoptotic cells in a dose-dependent fashion with a maximal effect at 100 microM (p < .0001). LY294002, the phosphatidylinositol 3-OH kinase (PI3K) inhibitor, and KT5823, the protein kinase G (PKG) inhibitor, reversed the antiapoptotic effect of M1.

CONCLUSIONS

The unoprostone metabolite M1 protects retinal neuro-glial progenitor R28 cells from apoptosis induced by serum deprivation via the PI3K and PKG pathways.

Commercially available prostaglandin analogs for the reduction of intraocular pressure: similarities and differences

Over the last 12 years, the pharmacological management of glaucoma and ocular hypertension has significantly changed with the introduction of the prostaglandin analogs, specifically, latanoprost, bimatoprost, and travoprost. Their ability to effectively reduce intraocular pressure with once-per-day dosing, their comparable ocular tolerability with timolol, and their general lack of systemic side effects have made them the mainstay of pharmacological therapy for glaucoma and ocular hypertension in most parts of the world. A review of their pharmacology reveals that they are all prodrugs that are converted to their respective free acids within the eye to activate the prostanoid FP receptor and to reduce intraocular pressure by enhancing the uveoscleral and the trabecular meshwork outflow pathways. A review of numerous prospective, randomized comparative studies indicates that no clinically significant differences exist among these agents regarding their ability to lower intraocular pressure.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Additional reduction in intraocular pressure achieved with latanoprost in normal-tension glaucoma patients previously treated with unoprostone

PURPOSE

To determine whether treatment with latanoprost eye drops is able to further reduce intraocular pressure (IOP) in normal-tension glaucoma (NTG) patients whose IOP has been well controlled with unoprostone.

PATIENTS AND METHODS

A total of 34 eyes (34 individuals) with NTG that had been treated with 0.12% unoprostone eye drops twice daily for >or=3 months were switched to treatment once daily with eye drops containing 0.005% latanoprost. IOP was measured before and 1, 2, and 3 months after the switch to latanoprost.

RESULTS

The mean IOP of all eyes was decreased significantly by 1.8, 2.9, and 2.3 mmHg at 1, 2, and 3 months after the switch from unoprostone to latanoprost treatment. The IOP of patients with an initial IOP of <or=12 or >12 mmHg was reduced by 11.0 or 19.9%, respectively, after 3 months on latanoprost. The IOP of 30 (88.2%) of the 34 eyes was further reduced by the switch from unoprostone to latanoprost.

CONCLUSIONS

Latanoprost reduced the IOP of NTG patients who had already been treated with unoprostone, even though both drugs are prostaglandin-related. Switching to latanoprost might thus achieve a maximal decrease in IOP and thereby better prevent damage to the optic nerve and loss of visual field in NTG patients.

Correlation between individual differences in intraocular pressure reduction and outflow facility due to latanoprost in normal-tension glaucoma patients

PURPOSE

The amount of intraocular pressure (IOP) reduction achieved by the use of latanoprost eyedrops varies among patients, and there are even nonresponders. This report examines whether there is any correlation between the amount of individual variability in IOP reduction and the uveoscleral outflow facility after latanoprost eyedrop instillation in normal-tension glaucoma patients.

METHODS

Sixteen normal-tension glaucoma patients (mean age, 56.4 years) were enrolled in the study to investigate the relationship between the amount of IOP reduction and outflow facility. Before treatment, subjects underwent circadian IOP measurement and then tonography, and the outflow facility was calculated. Subsequently, patients began treatment once daily with latanoprost instillation in one eye. After 4 weeks of daily latanoprost treatment, circadian IOP was measured again.

RESULTS

Mean pretreatment outflow facility was 0.23 +/- 0.05 microl/min per mmHg. On average, latanoprost instillation decreased IOP by 2.8 mmHg, but the reduction varied among individuals from -0.3 mmHg to 5.8 mmHg. No significant correlation was noted between the outflow facility and the IOP decline associated with latanoprost.

CONCLUSION

Because there was no significant correlation between individual IOP reduction by latanoprost and outflow facility, the differences in substantial change in uveoscleral outflow after latanoprost administration may be one explanation for the individual variation in IOP reduction after treatment with this drug.

Cost-effectiveness of monotherapy treatment of glaucoma and ocular hypertension with the lipid class of medications

PURPOSE

Cost-effectiveness evaluation of monotherapy with the newer lipid class of intraocular pressure (IOP)-lowering medications in glaucoma and ocular hypertension.

DESIGN

Retrospective pharmacoeconomic analysis.

METHODS

Analysis included all published studies measuring IOP reduction from untreated baseline with once-daily bimatoprost (Lumigan), latanoprost (Xalatan), or travoprost (Travatan) monotherapy in patients with elevated IOP. Percentage IOP reduction at the final study visit was calculated using the early morning IOP measurement to control for diurnal variation in IOP. Patient-weighted average percentage IOP reductions were computed for each medication. Cost per 2.5-ml bottle was determined using PriceAlert 2005 (February). Cost-effectiveness was defined as monthly cost of medication per patient-weighted average 1% reduction in IOP.

RESULTS

Studies included 951 bimatoprost, 1598 latanoprost, and 765 travoprost patients. The AWP in February, 2005 for a 2.5-ml bottle was 62.10 dollars for bimatoprost, 61.29 dollars for latanoprost, and 62.19 dollars for travoprost. Patient-weighted average IOP reduction was 32.4% for bimatoprost, 29.6% for latanoprost, and 29.0% for travoprost. Calculated cost-effectiveness was 1.92 dollars for bimatoprost, 2.07 dollars for latanoprost, and 2.14 dollars for travoprost. Incremental cost-effectiveness ratio (ICER) analysis showed an incremental cost of 0.29 dollars for each additional 1% IOP reduction provided by bimatoprost over latanoprost. The rank order of the cost-effectiveness of the drugs (bimatoprost > latanoprost > travoprost) was robust in sensitivity analyses to cost and efficacy.

CONCLUSIONS

On the basis of AWP and patient-weighted average percentage IOP reduction in published studies, bimatoprost had the most favorable cost-effectiveness among the drugs compared. Cost-effectiveness should be considered along with traditional clinical safety and efficacy measures to make individual and group healthcare decisions.

Analytic review of bimatoprost, latanoprost and travoprost in primary open angle glaucoma

OBJECTIVE

The objective of this review was to evaluate different measures of efficacy of the intraocular pressure (IOP) lowering lipid class agents bimatoprost, latanoprost and travoprost in the treatment of primary open angle glaucoma. Study arms of timolol in trials including the above mentioned lipid class drugs were also included.

METHODS

MEDLINE and EMBASE were searched for randomized clinical trials including one or more of the lipid class drugs bimatoprost, latanoprost and travoprost. The study results were pooled, and the simple, weighted IOP-lowering efficacy was compared among the lipid class drugs and timolol, where data were available. Efficacy parameters were reviewed, including mean reduction of IOP and percentage of patients achieving different levels of IOP.

RESULTS

161 articles were identified of which 42 were included in the analysis. A total of 9295 patients participated in the included trials. Based on all studies, timolol on average had a weighted mean IOP reduction of 22.2%, while latanoprost, travoprost and bimatoprost had a weighted mean IOP reduction of 26.7%, 28.7% and 30.3%, respectively. Analysis of target achievement to various IOP levels shows that bimatoprost seems more efficacious than latanoprost. The direct comparisons (head-to-head studies) also show that bimatoprost is the most efficacious treatment, however it is not conclusive whether latanoprost or travoprost is better in reducing IOP.

CONCLUSIONS

This review shows that bimatoprost seems to be the most efficacious treatment in lowering IOP. Head-to-head studies confirm this.

Clinical Predictors of Latanoprost Treatment Effect

PURPOSE

To determine the relationship between latanoprost efficacy and clinical features of glaucoma.

PATIENTS AND METHODS

Study design was retrospective, observational case series. The charts of all patients who underwent a one-eyed therapeutic trial of latanoprost during the course of their clinical care between 1997 and 2001 were reviewed. Intraocular pressures of both eyes prior to and one month after initiation of latanoprost were recorded. Latanoprost treatment effect was calculated by subtracting the change in intraocular pressure (IOP) in the fellow eye from the change in the treated eye. The effect of optic disc stage, age, race, sex, diagnosis, involved eye, type and number of other glaucoma medications, pattern of cupping (concentric, focal, or indeterminate), and pre-treatment IOP was correlated with the treatment effect. The stage of glaucoma was determined by determining the disc damage likelihood scale (DDLS) stage.

RESULTS

One hundred eighty-six cases were included. Latanoprost treatment effect was 4.5 +/- 5.7 mm Hg, was moderately correlated with pre-treatment IOP (Pearson's r = 0.527, P < 0.01), and was weakly inversely correlated with advancing disc stage (Pearson's r = -0.194, P < 0.01) and age (Pearson's r = -0.175, P < 0.05). It was independent of the other variables studied (P > 0.05).

CONCLUSION

Most clinical parameters examined in this study were not correlated with latanoprost treatment response. A moderate direct correlation was noted with pre-treatment IOP and a weak inverse correlation was noted with optic disc stage and age.

Intraocular pressure fluctuations in response to the water-drinking provocative test in patients using latanoprost versus unoprostone

Impairment of outflow facility in glaucoma causes large intraocular pressure (IOP) fluctuations that have been shown to be a risk factor for disease progression. The water-drinking provocative test (WDT) has been proposed as an indirect measurement of outflow facility to compare intraocular pressure responses of glaucoma eyes to different drugs. This study was a double-masked, randomized, parallel-group clinical trial comparing the IOP fluctuations in response to the WDT in patients using latanoprost versus unoprostone. After completing a wash-out of ocular hypotensive medications, patients with primary openangle glaucoma or ocular hypertension were randomized to receive either latanoprost (N=40) or unoprostone (N=42). IOP was measured before treatment and at 8 weeks after treatment (baseline IOP for WDT), followed by the WDT. IOP fluctuations and maximum IOP after water ingestion were compared between the two groups. Analysis of covariance was used to adjust for the effects of baseline IOP and treatment efficacy. The mean percentage reduction of IOP was 27% in patients using latanoprost, as compared to 13% in patients using unoprostone (p<0.001). Patients on treatment with latanoprost had significantly less IOP fluctuations in response to the WDT, compared to patients using unoprostone. From an overall baseline IOP of 20.0 mmHg and an overall treatment efficacy of 20%, the mean+/-standard error of the mean (SEM) of the IOP fluctuation during the WDT was 5.3+/-0.4 mmHg in the unoprostone group, and 3.6+/-0.4 mmHg in the latanoprost group (p=0.005, ANCOVA). This could represent an additional benefit of latanoprost over unoprostone in controlling the intraocular pressure of glaucomatous patients.

Switching to latanoprost monotherapy for 24 weeks in glaucoma patients

PURPOSE

To investigate the intraocular pressure lowering effect in glaucoma patients switched to latanoprost therapy from isopropyl unoprostone given as monotherapy or in combination with a beta-blocker.

METHODS

Patients with primary open angle glaucoma or normal tension glaucoma treated with 0.12% isopropyl unoprostone as monotherapy or in combination with a beta-blocker were eligible for this single-center clinical study. Of the 51 patients (51 eyes) enrolled, 18 were men and 33 were women aged 62.1 +/- 12.3 years (mean +/- SD). Twenty-two patients had primary open angle glaucoma, and 29 patients had normal tension glaucoma. Intraocular pressure was measured twice within 3 months prior to the switch, and the mean value was taken as the baseline. The patients were then switched to latanoprost (0.005%) monotherapy (once-daily administration), and changes in intraocular pressure were monitored. One physician measured intraocular pressure after 4, 8, 16, and 24 weeks of administration in this 24-week study.

RESULTS

The mean intraocular pressures were 16.0 +/- 2.4 mmHg at baseline, 13.7 +/- 2.3 mmHg after 4 weeks, 13.1 +/- 2.1 mmHg after 8 weeks, 13.6 +/- 2.0 mmHg after 16 weeks, and 13.3 +/- 2.4 mmHg after 24 weeks. A significant decrease in intraocular pressure was noted at all time points in both groups (paired t-test, p < 0.0001), and the intraocular pressure lowering effect persisted through week 24 of administration (analysis of variance, p < 0.0001).

CONCLUSIONS

Switching to latanoprost monotherapy elicits further reduction in intraocular pressure in patients with primary open angle glaucoma or normal tension glaucoma.

Effect of Different Dose Schedules of 0.15% Unoprostone Isopropyl on Intraocular Pressure and Pupil Size in the Glaucomatous Beagle

The changes in intraocular pressure (IOP) and pupil size (PS) after instillations of 0.15% unoprostone isopropyl (Rescula, Novartis Ophthalmics, Duluth, GA) were investigated in the spontaneous glaucoma Beagle model. From the first-day baseline IOP of 27.3+/-3.2 mmHg placebo eye and 32.8+/-5.1 mmHg control eye, the mean+/-standard error of the mean (SEM) diurnal changes after 0.15% unoprostone, at 8 AM once-daily for the next 4 days, were 15.5+/-1.3 mmHg, 14.7+/-1.9 mmHg, 16.1+/-1.1 mmHg, and 17.0+/-1.5 mmHg, respectively, and were significantly different from the control eye. After 0.15% unoprostone was instilled at 8 PM, the mean+/-SEM baseline changes from the baseline IOP (insert drug eye 9 AM) in the drug eyes were 5.9+/-2.5 mmHg, 5.2+/-4.1 mmHg, 9.7+/-2.5 mmHg, and 3.6+/-3.6 mmHg, respectively. When 0.15% unoprostone was instilled twice-daily, the mean+/-SEM baseline IOP (insert drug eye 9 AM) changes were 13.6+/-0.7 mmHg, 13.9+/-1.4 mmHg, 11.3+/-1.0 mmHg, and 9.3+/-1.4 mmHg, respectively, and were significantly different from the control eyes. Miosis occurred within 2 hours and lasted several hours. Unoprostone isopropyl instilled once-daily (AM or PM), as well as twice-daily, produces significant decreases in IOP and PS in the glaucomatous Beagle.

Low incidence of iris pigmentation and eyelash changes in 2 randomized clinical trials with unoprostone isopropyl 0.15%

OBJECTIVE

To assess whether iris color and eyelash changes occur with the use of unoprostone for 2 years.

DESIGN

The 2 clinical trials described herein were prospective, randomized, double-masked, active-controlled, parallel group, multicenter studies.

PARTICIPANTS

A total of 1131 patients with primary open-angle glaucoma or ocular hypertension participated in 2 clinical trials and received either unoprostone isopropyl 0.15% (659), timolol maleate 0.5% (331), or betaxolol hydrochloride 0.5% (141), 1 drop per eye twice daily for up to 24 months.

METHODS

Color photographs (1:1 magnification) were taken of the iris and eyelid of each patient at baseline and at regular intervals thereafter through month 24 using a standardized camera system. Photography included 7 views of each eye plus a calibration photograph and a patient identification photograph, for a total of 16 photographs per patient per visit. Two independent (masked) readers subjectively compared baseline iris colors to subsequent visits. Side view photographs of the upper and lower eyelashes were used for the eyelash length analysis, with each having sufficient depth of field and a sufficient number of eyelashes in focus. Similarly, frontal eyelash views were used for the eyelash density analysis.

MAIN OUTCOME MEASURES

Changes from baseline in iris color and eyelash length and density within and between treatment groups.

RESULTS

Seven cases of iris color change (1.06%) were confirmed in patients treated with unoprostone for up to 24 months; no confirmed cases were reported in the timolol or betaxolol groups. In the unoprostone group, cases of iris color change were confirmed at months 12 (1 case), 18 (2 cases), and 24 (4 cases). No clinically relevant differences were observed among treatment groups for changes from baseline in eyelash length or density.

CONCLUSION

Although iris hyperpigmentation and abnormal eyelash changes may occur after treatment with unoprostone, the incidence of these events appears to be low in the 2-year clinical study.

Bimatoprost versus latanoprost in lowering intraocular pressure in glaucoma and ocular hypertension: results from parallel-group comparison trials

This review evaluated the clinical evidence of the comparative efficacy and safety of bimatoprost and latanoprost in lowering intraocular pressure (IOP) in patients with glaucoma and ocular hypertension. Four head-to-head, randomized, and controlled clinical trials of bimatoprost and latanoprost with treatment periods ranging from 1 to 6 months were identified from searches of the MEDLINE database through February 2004. According to a review and comparison of the results, bimatoprost, when compared with latanoprost, was associated with greater mean reductions in IOP, greater mean increases in the percentage of patients demonstrating target IOP, and greater response rates. The differences between drugs were not always statistically significant. Overall, the between-group differences in mean IOP ranged from 0 to 1.5 mm Hg. In 92% of the IOP measurements, the mean IOP was lower among patients given bimatoprost than among those given latanoprost; in the remaining 8%, the IOP reduction was equal. Transient, mild conjunctival hyperemia was the most frequently reported adverse effect associated with either drug, but it occurred more frequently with bimatoprost. Overall, both drugs were well tolerated. As a 1-mm Hg change in IOP has been shown to reduce the risk of progression in patients with glaucoma (according to the Early Manifest Glaucoma Trial), the greater efficacy demonstrated by bimatoprost in lowering IOP may be clinically significant.

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.

Current management of glaucoma

PURPOSE OF REVIEW

This study reviews current concepts in the goals of glaucoma therapy, interventional sequence, and options for the management of glaucoma in light of recent clinical trials.

RECENT FINDINGS

Recent randomized prospective trials of ocular hypertension and glaucoma have provided evidence for more specific treatment goals in glaucoma therapy. In addition, the advent of the prostaglandin analogs, advances in laser technology, and innovative techniques for filtering surgery have expanded the armamentarium that ophthalmologists use in the treatment of glaucoma.

SUMMARY

Despite continued advances in laser and incisional surgery, medical therapy still appears to be the primary means by which intraocular pressure is controlled. Initial medical therapy has changed with the introduction of prostaglandin analogs, which are replacing beta-antagonists as the drug of first choice. Laser trabeculoplasty, using either photocoagulative (argon and diode) or photodisruptive (frequency doubled Nd:YAG) lasers, is still reserved for patients who do not improve with medical therapy, although there is good evidence that initial laser trabeculoplasty is just as effective as initial medical therapy. Trabeculectomy with antifibrotic agents (5-fluorouracil or mitomycin C) is still the next step in intraocular pressure control, and glaucoma drainage implants are reserved for refractory cases. Cyclophotocoagulation is a last resort procedure because of poor visual outcomes and is reserved for patients with intractable pain and vision thought not to be useful.

The safety and efficacy of unoprostone 0.15% versus brimonidine 0.2%

PURPOSE

To compare the efficacy and safety of unoprostone versus brimonidine both given twice daily in ocular hypertensive or primary open-angle glaucoma subjects.

METHODS

After a 1-month washout period a baseline diurnal curve was measured every 2 hours from 08:00 hours (trough) to 20:00 hours in subjects with a trough intraocular pressure (IOP) and the pressure 24 mmHg. Qualified subjects were randomized to either brimonidine or unoprostone. After 6 weeks of treatment the period 1 diurnal curve was performed. Subjects were then switched to the opposite treatment for 6 weeks and the period 2 diurnal curve was performed.

RESULTS

A total of 33 subjects were included in this study. In the brimonidine-treated group the trough IOP 20.1 +/- 2.8 mmHg was reduced from baseline up to 8 hours after dosing. In the unoprostone-treated group the trough IOP was 19.5 +/- 3.0 mmHg, which was statistically equal to that of brimonidine (p = 0.21), was reduced from baseline for 12 hours after dosing. Brimonidine decreased the IOP statistically more than unoprostone at 10:00 and 12:00 hours (p < 0.0001 and p = 0.02, respectively), while unoprostone reduced the IOP more than brimonidine at 18:00 and 20:00 hours (p = 0.002 and p = 0.05, respectively). Safety levels were similar between groups, but unoprostone caused more ocular stinging than brimonidine (p = 0.008).

CONCLUSION

This study suggests that twice daily brimonidine demonstrates a statistically greater peak reduction in IOP than unoprostone. However, unoprostone, but not brimonidine, decreased IOP over the complete 12-hour daytime dosing cycle.

Brimonidine 0.2% vs unoprostone 0.15% both added to timolol maleate 0.5% given twice daily to patients with primary open-angle glaucoma or ocular hypertension

PURPOSE

To compare the efficacy and safety of brimonidine 0.2% vs unoprostone 0.15%, both added to timolol maleate 0.5% each given twice daily.

METHODS

In this prospective, multi-centred, double-masked, crossover comparison, patients were randomized to one treatment group for a 6-week treatment period, and then crossed over to the opposite treatment. Measurements were performed at 0800, 1000, 1600, 1800, and 2000 h at baseline and at the end of each treatment period.

RESULTS

In all, 33 patients entered this trial and 29 completed. The baseline trough intraocular pressure (IOP) was 23.3+/-2.4 and the diurnal curve IOP was 22.0+/-1.3 mmHg. For the brimonidine and timolol maleate treatment group, the trough IOP was 21.6+/-3.3 and the diurnal curve IOP was 19.8+/-2.1 mmHg, while the timolol and unoprostone treatment showed a trough IOP of 20.9+/-3.8 and a diurnal curve IOP of 19.3+/-2.4 mmHg. There was no significant difference between treatment groups at any time point for the diurnal curve, or in the reduction from baseline (P>0.05). Both treatments failed to statistically reduce the IOP from baseline at 1800 h. There was no difference between treatment groups regarding ocular and systemic unsolicited adverse events, but patients admitted to more dryness (P=0.02) and burning upon instillation (P<0.0001) with unoprostone by survey.

CONCLUSION

Brimonidine 0.2% or unoprostone 0.15% added to timolol maleate 0.5% provide similar efficacy and safety throughout the daytime diurnal curve.

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

OBJECTIVE

To evaluate changes in intraocular pressure and pupil size in glaucomatous dogs after instillation of 0.004% travoprost once in the morning, or once in the evening, or twice daily in 5-day multiple dose studies.

MATERIALS AND METHODS

Applanation tonometry (IOP) and pupil size (PS) measurements were obtained at 8 a.m., 10 a.m., 12 noon, 2 p.m. and 4 p.m. in eight glaucoma dogs. Methylcellulose (0.5% as placebo) was instilled in the control eye, and 0.004% travoprost was instilled in the opposite drug eye. Methylcellulose (0.5%) and 0.004% travoprost were instilled on the 2nd through to the 5th day with instillations in the morning (8.30 a.m.), or evening (8 p.m.), or twice daily (8.30 a.m. and 8 p.m.).

RESULTS

The mean +/- SEM diurnal changes from baseline IOP in the control and placebo eyes in all three studies ranged from 1.2 +/- 0.3 mmHg to 3.2 +/- 0.9 mmHg. The mean +/- SEM diurnal changes from the baseline IOP after 0.004% travoprost at 8 a.m. once daily for the next 4 days were 19.0 +/- 2.7 mmHg, 24.7 +/- 2.7 mmHg, 24.9 +/- 3.1 mmHg, and 24.7 +/- 3.1 mmHg, respectively, and were significantly different from the control eye. After travoprost was instilled at 8 p.m., the mean +/- SEM baseline changes from the baseline IOP in the drug eyes were 23.5 +/- 2.2 mmHg, 24.2 +/- 2.2 mmHg, 24.5 +/- 2.3 mmHg, and 24.2 +/- 2.3 mmHg, respectively. When 0.004% travoprost was instilled twice daily, the mean +/- SEM baseline IOP changes were 27.7 +/- 2.1 mmHg, 28.1 +/- 2.1 mmHg, 28.4 +/- 2.2 mmHg, and 28.5 +/- 2.2 mmHg, respectively, and were significantly different from the control eyes. Miosis of varying duration was frequent during the three studies.

CONCLUSION

Travoprost instilled once daily (a.m. or p.m.) as well as twice daily produces significant decreases in IOP and PS in the glaucomatous Beagle.

Efficacy and safety of timolol maleate/latanoprost fixed combination versus timolol maleate and brimonidine given twice daily

PURPOSE

To evaluate the efficacy and safety of the timolol maleate/latanoprost fixed combination (TLFC) given once each evening versus brimonidine and timolol solution given twice daily as concomitant therapy in primary open-angle glaucoma or ocular hypertension patients.

METHODS

Qualified subjects were begun on timolol alone twice daily for 1 month and then randomized to either TLFC or brimonidine and timolol concomitant therapy for 6 weeks. Patients were then switched to the other treatment regimen. Intraocular pressures (IOPs) were measured every 2 hours between 08 : 00 and 20 : 00 hours at baseline and at the end of periods 1 and 2.

RESULTS

This study found that in 32 subjects the IOP diurnal curve on timolol alone (20.9 +/- 2.8 mmHg) decreased to 17.9 +/- 3.2 mmHg when patients were treated with TLFC and to 19.0 +/- 2.4 mmHg when patients were treated with brimonidine and timolol (p = 0.02). Intraocular pressures at individual time-points were statistically similar between the groups at the 08 : 00 trough and 2 and 4 hours after dosing. However, beyond 4 hours after dosing, TLFC-treated subjects demonstrated a trend towards lower IOPs at each 2-hour time-point that was not statistically significant after a Bonferroni correction (p <or= 0.05). The incidence of both solicited and unsolicited side-effects was similar between groups.

CONCLUSION

This study suggests that TLFC given in the evening reduces the mean daytime diurnal IOP more than brimonidine and timolol given concomitantly twice daily.

Four years later: a clinical update on latanoprost

PURPOSE

Almost five years have elapsed since the introduction of latanoprost on several markets and considering the large number of publications dealing with it, the authors felt that it was worth re-evaluating the drug.

METHODS

The criterion used to select trials for inclusion in the review was: all articles mentioning the drug in common electronic data-bases; these were then screened and considered, on the basis of methodological quality.

RESULTS

Experimental data suggest that latanoprost acts by remodeling the extracellular matrix in the ciliary muscle, thus increasing the flow of aqueous humor through the ciliary muscle bundles of the uveoscleral pathway. POAG: Latanoprost persistently improves the pulsatile ocular blood flow in primary open angle glaucoma (POAG). Recent trials confirmed the greater IOP-lowering efficacy of latanoprost vs. timolol, dorzolamide, brimonidine and unoprostone. Trials lasting up to 24 months showed that latanoprost is effective in long-term treatment of POAG and ocular hypertension (OH), with no signs of loss of efficacy when compared to timolol or dorzolamide. Latanoprost provides better control of circadian IOP. Non-responders to beta-blockers should preferably be switched to latanoprost monotherapy before a combination therapy is started. The possibility of a fixed combination of latanoprost and timolol has been explored, with promising results. NTG: Latanoprost is effective in normal tension glaucoma (NTG), lowering IOP, improving pulsatile ocular blood flow and increasing ocular perfusion pressure. OTHER GLAUCOMAS: Latanoprost may provide effective IOP control in angle-closure glaucoma after iridectomy, in pigmentary glaucoma, glaucoma after cataract extraction and steroid-induced glaucoma. However, latanoprost was effective in only a minority of pediatric cases of glaucoma and is contraindicated in all forms of uveitic glaucoma.

SAFETY

In the articles reviewed, new or duration-related adverse events were reported.

Conjunctival hyperemia and the use of topical prostaglandins in glaucoma and ocular hypertension

The prostaglandin derivatives are thought to lower intraocular pressure (IOP) primarily by increasing uveoscleral outflow. The ocular side effect, hyperemia, appears to occur via a secondary, unrelated mechanism. Variations in the IOP-lowering effect and incidence of hyperemia associated with these drugs are a function of their different chemical structures. Among the currently approved prostaglandin derivatives, hyperemia occurs in as many as 50% of patients treated with travoprost and as few as 5% of patients treated with latanoprost. The side effect of hyperemia may be of concern to the ophthalmologist for at least 2 reasons: hyperemia may compromise the outcome of filtration surgery, and it may represent a cosmetic problem to the patient thereby leading to non-compliance. The extent to which hyperemia may contribute to patient noncompliance and the effect of administration of the prostaglandin derivatives on outcome of filtration surgery remain to be determined. Until more definitive data are available, when selecting a prostaglandin analogue for ocular hypotensive therapy, it seems prudent to choose an agent with a low incidence of hyperemia.

Timolol 0.5%/dorzolamide 2% fixed combination vs timolol maleate 0.5% and unoprostone 0.15% given twice daily to patients with primary open-angle glaucoma or ocular hypertension

OBJECTIVE

To compare the efficacy and safety of timolol 0.5%/dorzolamide 2% fixed combination vs timolol maleate 0.5% and unoprostone 0.15% given twice daily.

DESIGN

Prospective multicenter, randomized, double-masked, crossover comparison study.

METHODS

Primary open-angle glaucoma or ocular hypertension patients were randomly assigned to one of the treatment groups for a 6-week treatment period and then crossed over to the opposite treatment. Diurnal curve testing was performed at 8:00 AM, 10:00 AM, 4:00 PM, 6:00 PM, and 8:00 PM at baseline and the end of each treatment period. The run-in medicine was timolol twice daily for 28 days.

RESULTS

Thirty-two patients completed this trial. The baseline trough pressure was 24.3 +/- 3.0 mm Hg, and the diurnal curve was 23.4 +/- 3.2 mm Hg. For the fixed combination the treatment trough pressure was 20.8 +/- 4.1 mm Hg and the diurnal curve was 19.6 +/- 3.6 mm Hg, whereas timolol and unoprostone concomitant therapy showed a treatment trough pressure of 20.1 +/- 4.5 mm Hg and a diurnal pressure of 19.8 +/- 4.1 mm Hg. There was no significant difference between treatment groups at any time point, for the diurnal curve, or in the extended reduction from baseline. There was no difference between treatment groups regarding ocular and systemic unsolicited or solicited adverse events. Burning, stinging, and conjunctival hyperemia were the adverse events most noted. There were no serious adverse events during this trial.

CONCLUSIONS

This study suggests that both timolol/dorzolamide 2% fixed combination and concomitant timolol maleate 0.5% and unoprostone 0.15% therapy provide similar efficacy and safety throughout the daytime diurnal curve.

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.

Randomized clinical trial of latanoprost and unoprostone in patients with elevated intraocular pressure

PURPOSE

To compare the intraocular pressure (IOP)-lowering effect and safety of latanoprost 0.005% once daily with that of unoprostone 0.15% twice daily for patients with primary open-angle glaucoma or ocular hypertension.

DESIGN

Randomized clinical trial.

METHODS

In a prospective, 8-week, investigator-masked, parallel-group study conducted at numerous centers in the United States, 165 previously treated patients with IOP >or= 25 mm Hg in one or both eyes after washout were randomly assigned to receive either latanoprost 0.005% once daily in the evening or unoprostone 0.15% twice daily. Observations procedures were Goldmann applanation tonometry, best-corrected visual acuity, slit lamp biomicroscopy, and ophthalmoscopy. The main outcome measure was change in the mean of the IOPs measured at 8:00 AM, 12 noon, and 4:00 PM between baseline (before treatment) and after 8 weeks of treatment.

RESULTS

The change in the mean +/- SD of the IOPs measured at 8:00 AM, 12 noon, and 4:00 PM was -7.2 +/- 3.2 mm Hg (28%) for latanoprost (25.3 +/- 2.8 mm Hg at baseline to 18.2 +/- 2.8 mm Hg at 8 weeks) and -3.9 +/- 2.6 mm Hg (15%) for unoprostone (25.5 +/- 3.3 mm Hg at baseline to 21.6 +/- 4.0 mm Hg; P <or=.001. No serious adverse event related to either medication was reported.

CONCLUSIONS

Over an 8-week period, latanoprost 0.005% once daily lowered IOP more than unoprostone 0.15% twice daily in patients with elevated IOP. Both agents were safe and well tolerated.

A comparative clinical study of latanoprost and isopropyl unoprostone in Japanese patients with primary open-angle glaucoma and ocular hypertension

PURPOSE

To compare the efficacy and safety of latanoprost versus isopropyl unoprostone (unoprostone) in Japanese patients with primary open-angle glaucoma (POAG) or ocular hypertension (OH).

METHODS

An 8-week, multicenter, randomized, comparative study was performed in 48 Japanese patients with POAG or OH. Four patients (two in each group) withdrew from the study, but their data were included in the safety assessment but not in the intraocular pressure (IOP) evaluation. The patients were randomly treated with latanoprost 0.005% once daily or unoprostone 0.12% twice daily for 8 weeks. IOP was measured at baseline and 2, 4, and 8 weeks after treatment. In addition, ocular and systemic adverse events were recorded.

RESULTS

The baseline IOPs were similar between the latanoprost (n = 25) and unoprostone (n = 19) groups (24.3 +/- 2.4 mm Hg vs 23.3 +/- 2.1 mm Hg, respectively, = 0.18). The IOP reductions from baseline at 2, 4, and 8 weeks after treatment were 5.8 +/- 2.4, 6.6 +/- 2.5, and 6.7 +/- 2.0 mm Hg in the latanoprost group, and 3.8 +/- 2.0, 3.5 +/- 2.3, and 3.3 +/- 3.0 mm Hg in the unoprostone group, respectively. The IOP reduction in the latanoprost group at 8 weeks was larger than that in the unoprostone group ( < 0.001, analysis of covariance). Five adverse events were observed in 4 (15%) of 27 patients in the latanoprost group, and five adverse events were observed in 4 (20%) of 21 patients in the unoprostone group. There was no difference in the incidence of adverse events between groups ( = 0.71).

CONCLUSION

Latanoprost produced a statistically greater reduction in IOP than unoprostone in Japanese patients with POAG or OH.

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.

Reappraising first-line treatment in glaucoma management

Despite treatment, glaucoma patients may still suffer vision loss because of inadequate control of intraocular pressure or late presentation. This article reviews the latest evidence supporting a reappraisal of first-line treatment in the management of glaucoma, including a review of latanoprost, recently approved for first-line treatment of glaucoma and ocular hypertension.

Current status of prostaglandin therapy: latanoprost and unoprostone

Latanoprost, a prostaglandin F(2alpha) analog prodrug, and unoprostone, an analog of a prostaglandin metabolite, have been shown to be effective in decreasing intraocular pressure when used alone or in combination with other ocular hypotensive agents. The increase in the uveoscleral outflow and some of the side effects are probably FP-receptor mediated, which may account for some differences between the cited drugs. This article reviews the recent literature available on the clinical efficacy of these prostanoids, as well as the studies directly comparing these drugs.

Medical treatment of normal tension glaucoma

Normal-tension glaucoma was previously thought to be pressure insensitive, as medical treatment hardly reduced intraocular pressure and it did not prevent visual field loss. In the last decade, however, evidence has shown that the treatment of normal-tension glaucoma by lowering intraocular pressure can slow the deterioration of visual fields, hence the glaucomatous process. It was shown that a reduction of IOP of at least 30% is needed to induce a favorable alteration in the course of normal-tension glaucoma. New agents, such as prostaglandin analogs, the alpha(2)-adrenoceptor agonist brimonidine, and carbonic anhydrase inhibitors, have become available and may be of use in the treatment of normal-tension glaucoma. Monotherapy with prostaglandin analogs may meet the target of a reduction of IOP with 30%, but combination therapy will be needed in many cases. Few studies have been performed with brimonidine, travoprost, and bimatoprost, and it is suggested that more attention should be given to studies with these agents, as about 30% of patients with open angles and glaucomatous visual field defects have normal-tension glaucoma. Although neuroprotection is the goal of the future, no hard data are available yet which demonstrate that treatment with these agents will indeed result in preservation of visual fields.

New glaucoma medications in the geriatric population: efficacy and safety

Glaucoma can be considered a disease of the aging eye. Most medications used to treat glaucoma are in topical eyedrop form and may cause numerous untoward systemic effects in older persons. In recent years, several new ocular hypotensive medications have become available. These medications are being used more commonly because there is a growing trend by ophthalmologists to aggressively lower intraocular pressure. Therefore, geriatricians require a comprehensive knowledge of medications used to treat glaucoma, in addition to an understanding of their mechanism of action profiles of untoward effects and possible interactions with other diseases or medications. Therefore, we performed a review of the medications recently introduced into clinical practice. We selected drugs approved by the U.S. Food and Drug Administration between 1996 and September 2001. The safety profiles of these agents and their untoward side effects were reviewed by class: topical carbonic anhydrase inhibitors (brinzolamide: ocular tolerance, taste perversion), beta-adrenoceptor antagonists (timolol: bradycardia and bronchospasm), alpha-adrenergic agonists (brimonidine: oral dryness, headache, and fatigue), and prostaglandin analogs (latanoprost, bimatoprost, travoprost, and unoprostone isopropyl: ocular hyperemia, iris color changes). The function of this review is to make geriatricians more aware of the efficacy and untoward effects of medications recently introduced into clinical practice. We recommend that geriatricians perform a medication review on all medications their patients use, including eye drops.

Prostaglandin analog treatment of glaucoma and ocular hypertension

OBJECTIVE

To review available data related to the use of prostaglandin analogs (bimatoprost, latanoprost, travoprost, unoprostone) in the management of ocular hypertension and open-angle glaucoma.

DATA SOURCES

Primary and review articles were identified from a MEDLINE search (1966-May 2001) and requested information from product manufacturers.

STUDY SELECTION AND DATA EXTRACTION

All available information, including that published in articles and abstracts, which was deemed relevant was included in this review. Limited data have been published to date.

DATA SYNTHESIS

The prostaglandin analogs appear to be effective, well-tolerated agents for the reduction of intraocular pressure (IOP) in patients with primary open-angle glaucoma and ocular hypertension. This drug class offers an alternative for patients who do not achieve control with another topical antiglaucoma agent or for those with a contraindication to first-line therapy with beta-adrenergic antagonists. Based on preliminary clinical data, bimatoprost, latanoprost, and travoprost appear to be at least as effective as timolol, while the effectiveness of unoprostone is similar or slightly less. Prostaglandin analogs may be used in conjunction with other antiglaucoma medications, although further studies must establish the optimal combination. Whether clinical experience will yield outcomes in favor of one of the prostaglandin analogs remains to be determined. Patients should be educated on adverse events associated with prostaglandin analogs, particularly the potential for changes in the pigmentation of the iris and eyelashes.

CONCLUSIONS

Bimatoprost, latanoprost, and travoprost appear to be equivalent to the current standard of therapy in the topical treatment of elevated IOP. Further clinical data published in article versus abstract format is required to better assess potential differences among these 3 agents.

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.

A comparison of intraocular pressure-lowering effect of prostaglandin F2 -alpha analogues, latanoprost, and unoprostone isopropyl

PURPOSE

To compare the intraocular pressure-lowering effect of unoprostone isopropyl (unoprostone) 0.12% and latanoprost 0.005%. A correlation between the intraocular pressure-lowering effect of unoprostone and latanoprost was also evaluated.

METHODS

A single-masked randomized study included 18 patients between 49 and 68 years (mean, 60.7 +/- 5.1 years) with an intraocular pressure of both eyes from 21 to 27 mm Hg. The patients were prospectively randomized to receive latanoprost in the right eye and unoprostone in the left eye, or unoprostone in the right eye and latanoprost in the left eye. The patients were followed up for 8 weeks. This study evaluated the intraocular pressure-lowering effect and incidence of drug-related side effects.

RESULTS

Mean baseline intraocular pressure was 22.8 +/- 1.2 mm Hg in latanoprost-treated eyes and 22.4 +/- 1.0 mm Hg in unoprostone-treated eyes; there was no statistically significant difference between these groups. Mean intraocular pressure at 8 weeks after the start of the administration was 16.7 +/- 2.0 mm Hg in latanoprost-treated eyes and 19.0 +/- 1.5 mm Hg in unoprostone-treated eyes. Patients in the latanoprost-treated group showed a greater intraocular pressure reduction compared with those in the unoprostone-treated group. Mean intraocular pressure changes in latanoprost-treated eyes were significantly greater at every visit (P < 0.0001). A change of intraocular pressure at 8 weeks in the latanoprost-treated eyes was significantly correlated with that in the contralateral unoprostone-treated eyes (r = 0.665, P = 0.0013) (Figure). There was no significant difference in the rate of ocular side effects between latanoprost- and unoprostone-treated eyes.

CONCLUSIONS

Latanoprost appears to have a more beneficial effect for intraocular pressure control compared with unoprostone. An intraocular pressure reduction in the latanoprost-treated eyes was significantly correlated with that in the contralateral unoprostone-treated eyes. There was no significant difference in the incidence of ocular side effects between both drugs. Further investigation using more cases and longer follow-up periods are needed.