In vitro effects of preservative-free and preserved prostaglandin analogs on primary cultured human conjunctival fibroblast cells

Effects of topical prostaglandin drops on angiogenesis in an in ovo chick chorioallantoic membrane model

BACKGROUND

To investigate the effects of bimatoprost, latanoprost and travoprost on angiogenesis in the chick chorioallantoic membrane (CAM) model in ovo.

MATERIALS AND METHODS

Fifty fertilized specific-pathogen-free chick eggs were used in this preclinical, prospective, experimental embryo study. Eggs were randomly distributed into 5 groups of ten eggs. Eggs were placed in the incubator after disinfection of their shells with alcohol and monitored appropriate temperature and humidity. On the 3rd day of incubation, a small window was opened on the eggshell. Bimatoprost in group 1, latanoprost in group 2, travoprost in group 3, bevacizumab in group 4, phosphate-buffered-saline (PBS) used in group 5 was applied by injection to CAM. The sterile film was glued onto the broken part of the shell and the eggs were placed in the incubator again. On the 8th day of incubation, eggs were opened and vascular structures on CAMs were examined. Digital photographs were taken, analysed in the ImageJ open source image processing software and differences between groups were evaluated. Thereafter, VEGF (Vascular endothelial growth factor) levels were measured appropriately in the embryo samples.

RESULTS

All embryos in the prostaglandin groups and the PBS control group were observed to have life signs confirmed by heart rate. In 8 embryos in the bevacizumab group, no life signs were confirmed, while 2 embryos with life signs showed severe hypoplasia. Vascular density, number of vessels and VEGF levels in the bimatoprost, latanoprost and travoprost groups, there were statistically significantly higher than the PBS control group.

CONCLUSION

This study demonstrates that topical prostaglandin drops increase angiogenesis in the chick CAM model in ovo.

Ocular Surface Changes in Prostaglandin Analogue-Treated Patients

Glaucoma is the second leading cause of blindness globally. Reducing intraocular pressure (IOP) has been acknowledged to be the main therapy for glaucoma. Prostaglandin analogues (PGAs) have become the first-line therapy for patients with glaucoma due to their powerful efficacy for lowering (IOP). However, usage of PGAs can also cause several notable side effects, including the changes in ocular surface. The relationship between PGAs and ocular surface changes is complicated and still remains unclear. In the present review, we summarize the recent studies of the effects of PGAs on ocular changes as well as the possible mechanisms that might provide new considerations during clinical medication.

Tear biomarkers in latanoprost and bimatoprost treated eyes

Purpose

Prostaglandin analogues (PGA’s) are the mainstay and first line of treatment in current glaucoma practise. Though latanoprost and bimatoprost are the most commonly used PGA’s with minimal side effects at lower concentrations like bimaotoprost 0.01%, direct comparison of their cytokine/MMP profile in tears has not been evaluated earlier. The study intends to ascribe PGA to the upregulation of MMPs, Cytokines and Chemokines mediating varied pathways to result in side effects of the drugs.

Methods

Tear sample collection was done from outer canthus of 30 eyes of 30 patients (primary open angle glaucoma (n = 26 and n’ = 20), normal tension glaucoma (n = 4 and n’ = 10), in latanoprost (n) 0.005% and bimatoprost (n’) 0.01% group respectively, with a mean age of 62±10.5 years) on >6 months of PGA use using Tear flo^TM Schirmer filter strip. Tear samples from 30 eyes of 30 cataract patients without drug treatment were used as the control. Gelatinolytic activity of MMP-9 and MMP-2 were examined by substrate gelatine zymography MMP-1 and TIMP-1 concentrations from tears samples with PGAs were evaluated by ELISA while cytokine concentration in the eluted tears was evaluated using a convenient bioplex kit assay (Milliplex MAP kit, HCYTMAG-60K-PX41, Millipore, Massachusetts, United States). The mean duration of use of PGA in both groups did not differ significantly (median 1.3 years in bimatoprost and 1.1 years in latanoprost eyes, p = 0.6).

Results

The tear MMP-9 expression was higher in eyes receiving latanoprost while the MMP-2 expression was higher in eyes receiving bimatoprost with MMP1 protein levels being higher in the former. Latanoprost treated eyes had marginally elevated tear cytokines involved in tissue remodelling while bimatoprost eyes showed elevated cytokines regulating allergic pathways.

Conclusion

Differential cytokine and MMP expression indicates differential signalling pathways mediating different cellular effects (evident as clinical and side effects) with the two drugs which can be explored further.

The Role of the P2X7 Receptor in Ocular Stresses: A Potential Therapeutic Target

The P2X7 receptor is expressed in both anterior and posterior segments of the eyeball. In the ocular surface, the P2X7 receptor is activated in case of external aggressions: preservatives and surfactants induce the activation of P2X7 receptors, leading to either apoptosis, inflammation, or cell proliferation. In the retina, the key endogenous actors of age-related macular degeneration, diabetic retinopathy, and glaucoma act through P2X7 receptors’ activation and/or upregulation of P2X7 receptors’ expression. Different therapeutic strategies aimed at the P2X7 receptor exist. P2X7 receptor antagonists, such as divalent cations and Brilliant Blue G (BBG) could be used to target either the ocular surface or the retina, as long as polyunsaturated fatty acids may exert their effects through the disruption of plasma membrane lipid rafts or saffron that reduces the response evoked by P2X7 receptor stimulation. Treatments against P2X7 receptor activation are proposed by using either eye drops or food supplements.

Tafluprost Ophthalmic Solution 0.0015 %: A Review in Glaucoma and Ocular Hypertension

Tafluprost ophthalmic solution 0.0015 % preserved with benzalkonium chloride (BAK) 0.001 % is available in several Asian countries, including Japan. In pivotal trials, BAK-preserved tafluprost ophthalmic solution 0.0015 % lowered intraocular pressure (IOP) more effectively than placebo in Asian patients with normal-tension glaucoma and was at least as effective as latanoprost ophthalmic solution 0.005 % in Asian patients with primary open-angle glaucoma or ocular hypertension. In other prospective studies in Asian patients with glaucoma or ocular hypertension, tafluprost ophthalmic solution 0.0015 % was at least as effective as latanoprost ophthalmic solution 0.005 % or travoprost ophthalmic solution 0.004 % in terms of IOP lowering, and was considered easier to use and/or store. The efficacy of tafluprost ophthalmic solution 0.0015 % was maintained in the longer term. Tafluprost ophthalmic solution 0.0015 % was generally well tolerated. In conclusion, BAK-preserved tafluprost ophthalmic solution 0.0015 % remains a useful option for the treatment of Asian patients with glaucoma and ocular hypertension.

Comparison of the Efficacy of Fluorometholone With and Without Benzalkonium Chloride in Ocular Surface Disease

PURPOSE

The purpose of this study was to compare the cytotoxicity and antiinflammatory effect of preserved and unpreserved 0.1% fluorometholone (FML).

METHODS

Drug-induced morphological changes and cytotoxicity were examined in human corneal epithelial cells. Dry eye was induced in mice by treatment with 0.2% benzalkonium chloride (BAC) for the first 2 weeks, and then, the eyes (4 groups; Normal saline, BAC, preserved FML, and unpreserved FML) were treated thrice daily with each formulation for the next 2 weeks. Corneal tissues were embedded in paraffin and stained with hematoxylin and eosin for histopathological examination. Immunofluorescence staining was performed for tumor necrosis factor-α, interleukin-6, and human leukocyte antigen-DR. Terminal deoxynucleotidyl transferase dUTP nick end labeling assay was performed to evaluate drug-induced cytotoxicity.

RESULTS

BAC and preserved FML caused cell shrinkage and detachment from the plate in a dose-dependent manner, and cell viability decreased significantly. However, cytotoxicity was reduced on treatment with unpreserved FML. Hematoxylin-eosin staining revealed surface desquamation, irregular surface, loss of cell borders, and stromal shrinkage in the group treated with BAC. On BAC exposure, tumor necrosis factor-α, interleukin-6, and human leukocyte antigen-DR were strongly detected, and cytotoxicity was markedly increased, as evidenced by a positive result in the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Ocular surface damage and inflammation were slightly reduced on treatment with preserved FML. In comparison, unpreserved FML did not induce morphological changes; moreover, decreased cell cytotoxicity and ocular surface inflammation were observed.

CONCLUSIONS

The cytotoxicity of antiinflammatory eye drops evaluated in this study was induced by the preservative BAC. Accordingly, unpreserved FML is more effective than preserved eye drops in decreasing ocular inflammation.

Effect of benzalkonium chloride-free travoprost on intraocular pressure and ocular surface symptoms in patients with glaucoma previously on latanoprost: an open-label study

Background

Prostaglandin analogs reduce intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension; however, these medications may affect the ocular surface and elicit ocular discomfort when preserved with benzalkonium chloride (BAK).

Methods

This was an open-label, single-arm study conducted in Latin America from February 2012 to May 2013. Patients with open-angle glaucoma or ocular hypertension who were intolerant of latanoprost 0.005 % were transitioned to receive once-daily BAK-free travoprost 0.004 % containing polyquaternium-1 (Travatan® preserved with POLYQUAD® [PQ], Alcon Laboratories, Inc; Fort Worth, TX) for 12 weeks. Mean change in IOP from baseline (primary efficacy endpoint) and the percentage of patients who achieved a target IOP of ≤18 mmHg were evaluated at all on-therapy visits. Ocular hyperemia, patient preference, and self-projected adherence were assessed at week 12. Adverse events (AEs) were monitored throughout the study.

Results

All enrolled patients were included in the analysis (n = 191); the majority of patients (90.6 %, n = 173/191) completed the study. Mean (SD) patient age was 67.5 (11.3) years, and mean baseline IOP was 14.8 mmHg. Mean IOP was reduced by 0.94 mmHg at week 6 and by 1.09 mmHg at week 12 (P < 0.001 for both). A greater percentage of patients achieved a target IOP of ≤18 mmHg at week 6 (93.1 %; n = 163/175) and week 12 (93.3 %; n = 166/178) compared with baseline (89.5 %; n = 171/191). There was a 10.5 % increase in the percentage of patients with “none/trace” amounts of hyperemia. Most patients preferred the study medication (81.5 %; n = 141/173) and were confident that they would adhere to their preferred medication (90.8 %; n = 157/173). No serious AEs were reported, and eye irritation (3.7 %; n = 7/191) was the most common treatment-related AE.

Conclusions

Transitioning from BAK-containing latanoprost 0.005 % to BAK-free travoprost 0.004 % preserved with PQ reduced IOP in patients with open-angle glaucoma or ocular hypertension who were intolerant of latanoprost. BAK-free travoprost 0.004 % is a viable alternative for patients who require switching their IOP-lowering medications because of tolerability issues.

Trial registration

ClinicalTrials.gov identifier, NCT01510145

In Vivo Effects of Preservative-free and Preserved Prostaglandin Analogs: Mouse Ocular Surface Study

Purpose

Chronic use of topical hypotensive agents induces several side effects caused by preservatives. The purpose of this study was to evaluate the effects of prostaglandin analogs with varying concentrations of benzalkonium chloride (BAC), preservative-free (PF), and alternative preservatives on mouse corneal tissue.

Methods

Thirty-five, 8- to 10-week-old female C57BL/6 mice (five mice for each group) were used for this study. To the control group, we applied normal saline, and to each drug-treated group we applied 0.02% BAC, bimatoprost 0.01% (with BAC 0.02%), latanoprost 0.005% (with BAC 0.02%), travoprost 0.004% (with 0.001% polyquad) or tafluprost 0.0015% with/without 0.001% BAC, once a day (9 p.m.) for 4 weeks. Corneal fluorescein staining was evaluated in all groups. After harvest, the corneal tissues were embedded in paraffin and then Hematoxylin-Eosin stain was performed for histopathological examination. Immunofluorescence staining was done against TNF-α, IL-6, HLA DR, pJNK, and pAkt.

Results

In corneal fluorescein staining, severe punctate epithelial keratitis was seen in the groups of 0.02% BAC, 0.02% BAC containing bimatoprost 0.01% and latanoprost 0.005%. The surface desquamation, irregular surface, loss of cell borders, anisocytosis and stromal shrinkage were observed in the groups of BAC-containing eye drops. Moreover, the groups treated with BAC-containing eye drops have high inflammatory markers, significantly decreased cell viability-related signal, pAkt, and higher apoptosis-inducing signal, pJNK, than the control group. On the other hand, travoprost 0.004% and PF tafluprost 0.0015% have less cellular morphologic changes, lower inflammation, and higher cellular viability than BAC-containing formulations.

Conclusions

Corneal damage, increased inflammation and apoptosis and low cell viability were observed in BAC-containing groups. PF or alternatively preserved glaucoma medications seem to be a reasonable and viable alternative to those preserved with BAC.

Effects of Four Formulations of Prostaglandin Analogs on Eye Surface Cells. A Comparative Study

We evaluated the cytotoxic effects of four prostaglandin analogs (PGAs) used to treat glaucoma. First we established primary cultures of conjunctival stromal cells from healthy donors. Then cell cultures were incubated with different concentrations (0, 0.1, 1, 5, 25, 50 and 100%) of commercial formulations of bimatoprost, tafluprost, travoprost and latanoprost for increasing periods (5 and 30 min, 1 h, 6 h and 24 h) and cell survival was assessed with three different methods: WST-1, MTT and calcein/AM-ethidium homodimer-1 assays. Our results showed that all PGAs were associated with a certain level of cell damage, which correlated significantly with the concentration of PGA used, and to a lesser extent with culture time. Tafluprost tended to be less toxic than bimatoprost, travoprost and latanoprost after all culture periods. The results for WST-1, MTT and calcein/AM-ethidium homodimer-1 correlated closely. When the average lethal dose 50 was calculated, we found that the most cytotoxic drug was latanoprost, whereas tafluprost was the most sparing of the ocular surface in vitro. These results indicate the need to design novel PGAs with high effectiveness but free from the cytotoxic effects that we found, or at least to obtain drugs that are functional at low dosages. The fact that the commercial formulation of tafluprost used in this work was preservative-free may support the current tendency to eliminate preservatives from eye drops for clinical use.

[Original preparations versus generics--latanoprost: how similar is different?]

BACKGROUND

To test the interchangeability of the commercially available (in Germany) latanoprost drugs and their generics respectively, the concentration of the active substance was tested. Guidelines of the European Medicines Agency postulate a sufficient bioequivalence, if the range of the agent is within 80-125% of the original drug.

METHODS

All compounds of latanoprost were procured registered. The concentration of latanoprost and benzalkoniumchloride was measured by high-performance liquid chromatography (HPLC) in a validated reference labroratory for 23 generics. In addition, the mean volume of drops and the pH of the formulation were measured. The packaging label and the readability of the enclosed information leaflet were checked.

RESULTS

All products contained less than 50 μg/ml latanoprost. The deviating reduction of the active substance (mean: - 7.39%, ± 2.8%) was accompanied by fluctions of the eyedrops' mass (mean: 0.03 g, ± 0.002 g). The concentration of benzalkonium chloride was mostly increased (median: 5.45%, min: - 2.5%, max: 11.5%). The pH of the original drug and the generics (median 6.78, min: 6.62, max: 6.81) was similar to the original drug, but was significantly different from an unpreserved formulation (pH 7.18). Due to type size, the packaging leaflet was illegible for humans with impaired vision.

CONCLUSIONS

Before prescribing generics in ophthalmology, different factors have to be considered, which might influence the amount of IOP lowering in effect. In the absence of healthcare research it is still unclear, how different bottle forms of eyedrops--such as appearance (e.g. Cyrillic characters) or pressure point (administration)--reduce the adherence of glaucoma patients.

Efficacy and tolerability of mono-compound topical treatments for reduction of intraocular pressure in patients with primary open angle glaucoma or ocular hypertension: an overview of reviews

AIM

To evaluate the existing evidence on relative efficacy and tolerability of topical mono-compound intraocular pressure (IOP)-lowering drugs in treatment of primary open angle glaucoma (POAG) and ocular hypertension (OHT).

METHODS

In this systematic review of systematic reviews/meta-analyses of randomized controlled trials a thorough and sensitive search of PubMed, Embase and Cochrane Databases was performed. Individual study methodological quality and quality of evidence were assessed using the AMSTAR checklist and the GRADE system, respectively. The relationships between individual drugs were evaluated based on the best available evidence.

RESULTS

Of the 133 initial non-duplicate records, 16 studies met the inclusion criteria. Five achieved an overall "moderate" (none achieved "high") quality of evidence and evaluated prostaglandin analogues (PGAs) - latanoprost, travoprost, and bimatoprost; timolol; "other beta-blockers;" carbonic anhydrase inhibitors (CAI) as a group or dorzolamide separately; and brimonidine. "Moderate quality" refers to efficacy and incidence of conjunctival hyperemia. Quality of evidence regarding other tolerability aspects was low. PGAs should be considered equivalent regarding efficacy, but latanoprost was relevantly better tolerated than the other two. Non-PGA compounds did not relevantly differ between each other in either efficacy or safety. Timolol and brimonidine were relevantly less effective than all PGAs. The same was true for CAI vs bimatoprost. Regarding tolerability, timolol was superior to all PGAs and brimonidine and CAI were superior to bimatoprost.

CONCLUSION

No high quality evidence on relative efficacy and tolerability of the most commonly used mono-compound IOP-lowering drugs for POAG/OHT exists. Moderate quality evidence indicates latanoprost as a treatment with the most favorable trade-off between benefits and harms.