Ocular irritation reversibility assessment of a laundry detergent using the Porcine Corneal Opacity Reversibility Assay (PorCORA): a focused study.

Consumer product manufacturers utilise a spectrum of alternative ocular irritation assays, as these tests do not require the use of live animals. Despite their usefulness, no regulatory-accepted assay assesses the reversibility of ocular damage, a key criterion of GHS ocular classification, like the rabbit eye test (i.e., Draize Rabbit Eye Test [DRET]) . The Porcine Corneal Opacity Reversibility Assay (PorCORA), an ex vivo intact corneal tissue culture model, predicts the reversibility of damage by ocular irritants. Inclusion of the damage reversibility endpoint in the PorCORA supplements other alternative test methods for ocular irritation, by assessing induced eye damage and the ability of this damage to reverse (heal) without the use of live animals to distinguish between Globally Harmonised System of Classification and Labelling of Chemicals (GHS) ocular classifications. In this focused study, results of a Bovine Corneal Opacity and Permeability (BCOP) test of a laundry detergent, neat and 10% dilution, (product mixture from S.C. Johnson & Son, Inc. [SCJ]) classified the product into GHS Category 1; however, the BCOP test cannot assess the reversibility of ocular damage. The laundry detergent was evaluated using the PorCORA, where ocular damage induced by the detergent was fully reversed within seven days. Evaluation of the reversibility of ocular damage using the PorCORA in this focused study can add strength to the weight-of-evidence (WoE) analysis approach in ocular hazard assessment. This WoE approach strengthens the argument that the PorCORA can be used to supplement BCOP data, and that this laundry detergent is not an irreversible eye irritant.

Further optimisation of a macromolecular ocular irritation test (OptiSafeTM).

PURPOSE: OptiSafeTM (OS) is a shelf stable, nonanimal test for ocular irritation. A recent database search found that half of the OS false positive (FP) materials were associated with reactive oxygen chemistries but were not eye irritants in vivo (based on historical rabbit studies by other groups). We hypothesized that naturally occurring tear antioxidants protect the eye from reactive chemistries in vivo and that specific tear chemistries might help explain why some materials are FP for nonanimal tests but are reported as nonirritants in the live animal. To test this hypothesis, a prior study evaluated tear antioxidants and found that the tear antioxidant ascorbic acid, added at human physiological tear levels to the OS test, specifically reduced the measured values for these FPs but did not reduce the true-positive rate. Based on these findings, the OS test method was further optimized. The purpose of the current study was to comprehensively evaluate the performance of the further optimized test method for detection of ocular irritants. MATERIALS AND METHODS: The OS test measures chemically induced damage to macromolecules and relates these measured values to ocular irritancy. To improve the performance of OS, we made updates to the material to be tested physiochemical handling procedures, prediction model, and test method to include tear-level concentrations of ascorbic acid. We then retested the 78 chemicals from the prior OS-coded validation study in triplicate and compared the accuracy of the 'nonirritant versus irritant' prediction for the further optimized method with the prior results. RESULTS: We report that for the detection of 'nonirritant' versus 'irritant' (GHS NC versus categories 2B/A and 1) test substances, the further optimized OS test with ascorbic acid compared with the original version has a FP rate that is reduced from 40.0 to 22.2%, the false-negative (FN) rate remains at 0.0%, and the accuracy improved from 80.3% to 89.2%. CONCLUSION: A comparison to OECD-adopted tests demonstrates that the further optimized OS test, like the original method, has a higher accuracy and lower FN rate for the detection of 'nonirritants' versus 'irritants' (GHS Category NC versus 2B/A and 1) than the other eye irritation tests (BCOP, EpiOcularTM Eye Irritation Test, ICE, Ocular Irritection®, and STE).

Evaluation of ocular symptoms in COVID-19 subjects in inpatient and outpatient settings.

PURPOSE: Evaluation of subtle ocular involvement and clinically significant conjunctivitis symptoms in a group of patients with COVID-19 in outpatient and inpatient settings. METHOD: Overall, 1083 patients infected with SARS-CoV-2 were recruited as subjects. Patients were divided into inpatients (group 1, n = 371) and outpatients (group 2, n = 712). Demographical and general medical data included age, sex, and comorbidities. Patients whose diagnosis was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR) were called by phone, and their chronic ocular disease, previous ocular surgery, ocular medication, contact lens wear and ocular irritation symptoms were queried during the active disease period. RESULTS: The mean age of the patients was 44.2 ± 16.5 (19-97) years; 635 (58.6%) were male, and 448 (41.4%) were female. Comorbidity, chronic ocular disease, ophthalmic medication and previous ocular surgery rates were significantly higher in group 1 (p < 0.05), while contact lens wear was not significantly different between groups. The main complaints received from patients were sore eye or burning sensation, foreign body sensation, itching and red eye and were significantly higher in group 1. Clinically significant conjunctivitis symptoms, such as red eye, ocular discharge and eyelid edema, were observed in 28 patients (2.6%), with 14 (3.8%) patients in group 1 and 14 (2%) patients in group 2. CONCLUSION: Clinically significant conjunctivitis symptoms were detected in 28 subjects in the inpatient and outpatient groups. As systemic findings of COVID-19 intensify.

Validation of the OptiSafe™ eye irritation test.

PURPOSE: OptiSafe is an in chemico test method that identifies potential eye irritants based on macromolecular damage following test chemical exposure. The OptiSafe protocol includes a prescreen assessment that identifies test chemicals that are outside the applicability domain of the test method and thus determines the optimal procedure. We assessed the usefulness and limitations of the OptiSafe test method for identifying chemicals not requiring classification for ocular irritation (i.e. bottom-up testing strategy). MATERIALS AND METHODS: Seventeen chemicals were selected by the lead laboratory and tested as an independent study. Ninety-five unique coded chemicals were selected by a validation management team to assess the intra- and interlaboratory reproducibility and accuracy of OptiSafe in a multilaboratory, three-phased validation study. Three laboratories (lead laboratory and two naïve laboratories) evaluated 35 chemicals, with the remaining 60 chemicals evaluated by the lead laboratory only. Test method performance was assessed by comparing classifications based on OptiSafe results to classifications based on available retrospective in vivo data, using both the EPA and GHS eye irritation hazard classification systems. No prospective in vivo testing was conducted. RESULTS: Phase I testing of five chemicals showed that the method could be transferred to naïve laboratories; within-lab reproducibility ranged from 93% to 100% for both classification systems. Thirty coded chemicals were evaluated in Phase II of the validation study to demonstrate both intra- and interlaboratory reproducibility. Intralaboratory reproducibility for both EPA and GHS classification systems for Phase II of the validation study ranged from 93% to 99%, while interlaboratory reproducibility was 91% for both systems. Test method accuracy for the EPA and GHS classification systems based on results from individual laboratories ranged from 82% to 88% and from 78% to 88%, respectively, among the three laboratories; false negative rates ranged from 0% to 7% (EPA) and 0% to 15% (GHS). When results across all three laboratories were combined based on the majority classification, test method accuracy and false negative rates were 89% and 0%, respectively, for both classification systems, while false positive rates were 25% and 23% for the EPA and GHS classification systems, respectively. Validation study Phase III evaluation of an additional 60 chemicals by the lead laboratory provided a comprehensive assessment of test method accuracy and defined the applicability domain of the method. Based on chemicals tested in Phases II and III by the lead laboratory, test method accuracy was 83% and 79% for the EPA and GHS classification systems, respectively; false negative rates were 4% (EPA) and 0% (GHS); and false positive rates were 40% (EPA) and 42% (GHS). Potential causes of false positives in certain chemical (e.g. ethers and alcohols) or hazard classes are being further investigated. CONCLUSION: The OptiSafe test method is useful for identifying nonsurfactant substances not requiring classification for ocular irritancy. OptiSafe represents a new tool for the in vitro assessment of ocular toxicity in a tiered-testing strategy where chemicals can be initially tested and identified as not requiring hazard classification.

Toxicology study of long-term administration of rhKGF-2 eye drops on rabbit corneas.

Keratinocyte growth factor -2 promotes corneal repair. Its mechanism of action involves regulating regeneration and migration of corneal cells, as well as activating corneal limbal stem cells. However, KGF-2 being a carcinogenic growth factor and its potential adverse effect in over dosage long-term treatment had not yet been reported. In this study, we used New Zealand white rabbits to study possible toxic effects of ocular administration of recombinant human keratinocyte growth factor-2 eye drops. Animals in the medium- and high-dose groups had some ocular irritant reactions during the course of drug administration; however this reaction was harmless to the cornea and it ended up when administration was stopped. Serum biochemistries were largely unaffected by treatment. Pathological examinations were unremarkable. We found that over-dosed administration of these eye drops caused some ocular irritation, but this irritant reaction was harmless to the eye, and it reversed after the drug was stopped. There were no apparent systemic effects of the drug.

Lack of respiratory and ocular effects following acute propylene glycol exposure in healthy humans.

OBJECTIVE: Propylene glycol (PG) is a widely used solvent, chemical intermediate and carrier substance for foods, pharmaceutical and cosmetic products. Professional and occupational exposure to PG aerosol and vapor may occur from theatrical smoke generators and during application of deicing products to airplanes. While PG is considered to have low toxicity, the results of one study suggested that brief (1-min) exposure to PG mist elicited ocular and respiratory effects in humans. Because the high concentrations and brief exposure duration in that study were not representative of most occupational exposures, a controlled experimental exposure study was conducted to clarify or confirm the earlier findings. MATERIALS AND METHODS: Ten males and 10 females were exposed to PG aerosol for 4 hrs at 20 and 100 mg/m3 and 30 min at 200 mg/m3. Total PG exposure concentrations (droplets plus gas phase) were 95.6, 442.4 and 871 mg/m3 for the three conditions, respectively. Participants rode a stationary bicycle to simulate physical effort at regular intervals during exposure. Objective measures evaluated in this study included ocular irritation via eye blink task and eye photography and pulmonary function via spirometry, while subjective measures included health symptoms ratings, irritation and dryness ratings of eyes, nose, throat and mouth. RESULTS: Objective measures of pulmonary function and ocular irritation did not reveal any exposure-related changes. Exposure-related changes in symptom reporting were observed; however, the highest symptom ratings did not exceed "slight" on the scale. CONCLUSIONS: The results indicate at the concentrations and acute durations tested, PG does not affect human respiratory function or produce ocular irritation.

Dose-Response Functions for the Olfactory, Nasal Trigeminal, and Ocular Trigeminal Detectability of Airborne Chemicals by Humans.

We gathered from the literature 47 odor and 37 trigeminal (nasal and ocular) chemesthetic psychometric (i.e., detectability or dose-response) functions from a group of 41 chemicals. Vapors delivered were quantified by analytical methods. All functions were very well fitted by the sigmoid (logistic) equation: y = 1 / (1 + e({-(x-C)/D})), where parameter C quantifies the detection threshold concentration and parameter D the steepness of the function. Odor and chemesthetic functions showed no concentration overlap: olfactory functions grew along the parts per billion (ppb by volume) range or lower, whereas trigeminal functions grew along the part per million (ppm by volume) range. Although, on average, odor detectability rose from chance detection to perfect detection within 2 orders of magnitude in concentration, chemesthetic detectability did it within one. For 16 compounds having at least 1 odor and 1 chemesthetic function, the average gap between the 2 functions was 4.6 orders of magnitude in concentration. A quantitative structure-activity relationship (QSAR) using 5 chemical descriptors that had previously described stand-alone odor and chemesthetic threshold values, also holds promise to describe, and eventually predict, olfactory and chemesthetic detectability functions, albeit functions from additional compounds are needed to strengthen the QSAR.

Tiered application of the neutral red release and EpiOcular™ assays for evaluating the eye irritation potential of agrochemical formulations.

Agrochemical formulations have been underrepresented in validation efforts for implementing alternative eye irritation approaches but represent a significant opportunity to reduce animal testing. This study assesses the utility of the neutral red release assay (NRR) and EpiOcular™ assay (EO) for predicting the eye irritation potential of 64 agrochemical formulations relative to Draize data. In the NRR, formulations with an NRR50 value ≤ 50 mg/mL were categorized as UN GHS Cat 1 and those >250 mg/mL were classified as UN GHS Non Classified (NC). The accuracy, sensitivity, and specificity were 78, 85 and 76% and 73, 85 and 61% for identifying UN GHS 1 and NC formulations, respectively. Specificity was poor for formulations with NRR50 > 50 to ≤250 mg/mL. The EO (ET-40 method) was explored to differentiate formulations that were UN GHS 1/2 and UN GHS NC. The EO resulted in accuracy, sensitivity, and specificity of 65%, 58% and 75% for identifying UN GHS NC formulations. To improve the overall performance, the assays were implemented using a tiered-approach where the NRR was run as a first-tier followed by the EO. The tiered-approach resulted in improved accuracy (75%) and balanced sensitivity (73%) and specificity (77%) for distinguishing between irritating and non-irritating agrochemical formulations.

Clinical effect of four different ointment bases on healthy cat eyes.

OBJECTIVE: To describe the effects of long-term treatment with four different eye ointment bases (OBs) in cats. ANIMALS STUDIED: Ten healthy cats. PROCEDURES: The study was performed in two periods. Four different OBs were tested. Hundred grams of OB contained the following: OB-A: 35.17 g liquid paraffin (lp), 64.83 g white petrolatum (wp); OB-B: 10.03 g lp, 84.95 g wp 5.02 g lanolin; OB-C: 18.34 g lp, 51.40 g wp, 25.00 mg KH2 PO4 , 57.00 mg K2 HPO4 , 18.90 g eucerinum anhydricum, 11.28 g water for injections; and OB-D: 70 g unguentum lanalcoli, 20 g lp, 10 g aqua conservans. One eye was treated, and the other served as a negative control. Cats received the OBs TID for 28 days. The two study periods were separated by a 4-month washout phase. Samples for conjunctival impression cytology, swabs for bacteriologic and mycologic examination, and cytobrush samples for FHV-1 and Chlamydophila felis PCR detection were obtained. Both eyes were examined daily. Severity of ocular symptoms was scored using a modified Draize eye irritation test. A total of five eyes were treated with OB-A, five with OB-B, four with OB-C, and five with OB-D. RESULTS: Treated eyes had significantly higher clinical scores. Eyes receiving OB-A had the highest overall clinical score. The results of bacteriologic and mycologic examination concur with the previously published data. All samples tested were negative for FHV-1 and Chlamydophila felis. There was no significant difference between treated and control eyes upon cytological examination. CONCLUSION: The application of OBs resulted in clinical symptoms in treated eyes. The long-term use of ointments is not well tolerated in cats and may lead to ocular irritation.

Cationic microemulsion of voriconazole for the treatment of fungal keratitis: in vitro and in vivo evaluation.

Aim: This investigation aimed to develop a voriconazole-loaded chitosan-coated cationic microemulsion (CVME) to treat fungal keratitis. Methods: Microemulsions were prepared using water titration, and the optimized microemulsion was coated with chitosan to prepare CVME. The physicochemical parameters, ocular irritation potential, in vitro antifungal efficacy and in vitro release studies were performed. The in vivo antifungal efficacy study was conducted in a fungal infection-induced rabbit eye model. Results: The developed CVME displayed acceptable physicochemical properties and excellent mucoadhesive behavior and showed a sustained release profile. Ex vivo and in vivo studies concluded that higher permeability and improved antifungal efficacy were observed for CVME than drug suspension (DS). Conclusion: The prepared CVME7 is a viable alternative to treating fungal keratitis with existing approaches.

Nanotechnology can help resolve problems that are currently associated with eye medications. Microemulsions (MEs) are mixtures containing tiny droplets of oil and water, which are made stable by ingredients called surfactants (meaning a type of soap) and co-surfactants. The ability for medications to be released slowly in MEs makes them suitable for eye medications because they reduce the number of times eye drops need to be used each day. This study wanted to create a medicine called voriconazole-loaded chitosan-coated cationic microemulsion (CVME) to treat a fungal infection in the eye called keratitis. We made MEs by gradually adding a combination of oil, surfactant, and water together. Then, we coated the best MEs with a substance called chitosan to make CVME. We tested its physical and chemical properties, whether it irritated the eyes, how well it could fight fungus, and how it released medicine. We tested CVME on rabbits with a fungal eye infection. CVME had good physical and chemical properties and stuck well to the mucus on the surface of the eyes. It released the medicine slowly. The system created in this study is very important for treating fungal infections because it helps the medicine stay on the eye surface longer and allows it to better reach the infected areas of the eye. CVME7 might be a better option for treating fungal keratitis instead of other methods that are currently used.

Expansion of the application domain of a macromolecular ocular irritation test (OptiSafe™).

The OptiSafe (OS) test is shelf-stable, macromolecular eye irritation test that does not include any animal ingredient or component ("vegan"). The purpose of this study was to evaluate the test's accuracy for an expanded application domain for both the original and recently updated OS method. This study involved the testing of additional ocular corrosives and previously excluded foaming agents ("surfactants") using both the original and updated OS methods and then combining these data with prior validation data for a total of 147 chemicals. Predictivity was evaluated by a statistical comparison of the OptiSafe predictions with historical in vivo "Draize" rabbit eye data for the same chemicals (from public databases). We report that for the detection of chemicals not requiring classification for eye irritation [Globally Harmonized System of Classification and Labeling of Chemicals (GHS) No Category], the accuracy, specificity, and sensitivity were 92.8%, 79.6%, and 100.0%, respectively, for the updated method; for the detection of chemicals inducing extreme eye damage/corrosion (GHS Category 1), the accuracy, specificity, and sensitivity were 79.4%, 71.8%, and 91.7%, respectively, for the updated method. Results indicate that both the original and updated methods have a high accuracy for the expanded application domain that included ocular corrosives and surfactants.

Tobramycin-loaded nanoparticles of thiolated chitosan for ocular drug delivery: Preparation, mucoadhesion and pharmacokinetic evaluation.

The present work aimed to develop nanoparticles of tobramycin (TRM) using thiolated chitosan (TCS) in order to improve the mucoadhesion, antibacterial effect and pharmacokinetics. The nanoparticles were evaluated for their compatibility, thermal stability, particle size, zeta potential, mucoadhesion, drug release, kinetics of TRM release, corneal permeation, toxicity and ocular irritation. The thiolation of chitosan was confirmed by 1H NMR and FTIR, which showed peaks at 6.6 ppm and 1230 cm-1, respectively. The nanoparticles had a diameter of 73 nm, a negative zeta potential (-21 mV) and a polydispersity index of 0.15. The optimized formulation, NT8, exhibited the highest values of mucoadhesion (7.8 ± 0.541h), drug loading (87.45 ± 1.309%), entrapment efficiency (92.34 ± 2.671%), TRM release (>90%) and corneal permeation (85.56%). The release pattern of TRM from the developed formulations was fickian diffusion. TRM-loaded nanoparticles showed good antibacterial activity against Pseudomonas aeruginosa. The optimized formulation NT8 (0.1% TRM) greatly increased the AUC(0-∞) (1.5-fold) while significantly reducing the clearance (5-fold) compared to 0.3% TRM. Pharmacokinetic parameters indicated improved ocular retention and bioavailability of TRM loaded nanoparticles. Our study demonstrated that the TRM-loaded nanoparticles had improved mucoadhesion and pharmacokinetics and a suitable candidate for effective treatment of ocular bacterial infections.

Polyaphron Formulations Stabilised with Different Water-Soluble Polymers for Ocular Drug Delivery.

As drug delivery to the eye has evolved over the last decades, researchers have explored more effective treatments for ocular diseases. Despite this, delivering drugs to the cornea remains one of the most problematic issues in ophthalmology due to the poor permeability of the cornea and tear clearance mechanisms. In this study, four different types of polyaphron formulations are prepared with 10% poloxamer 188 (P188), 10% poly(2-ethyl-2-oxazoline), 1% polyquaternium 10, and 3% sodium carboxymethylcellulose solutions mixed with 1% Brij® L4 in a caprylic/capric triglycerides solution. Their physicochemical characteristics, rheological properties, and stability are assessed. Additionally, a polyaphron with 3% polyquaternium 10 was prepared for the assessment of ex vivo corneal retention along with four other polyaphrons. The best retention on the ex vivo cornea was displayed by the 3% polyquaternium 10-based formulation. The 10% poloxamer 188 along with 1% polyquaternium 10-based polyaphrons appeared to be the most stable among the four prepared formulations. A toxicological evaluation of these formulations was performed using a slug mucosal irritation test and bovine corneal opacity and permeability assay, with all four polyaphrons proving good biocompatibility with ocular tissues. The developed drug delivery systems demonstrated an excellent potential for ocular drug delivery.

Effects of Face-Mask Use on Dry Eye Disease Evaluated Using Self-Reported Ocular Surface Disease Index Scores: A Cross-Sectional Study on Nurses in Saudi Arabia.

BACKGROUND: Wearing face masks has been an essential part of healthcare workers' lives since the coronavirus disease 2019 (COVID-19) pandemic. This study aims to determine the association between prolonged face mask-wearing and dry eye disorder (DED) among female nurses. METHODS: An online questionnaire-based cross-sectional study was conducted at King Abdulaziz University Hospital, Jeddah, Saudi Arabia, between May 2021 and February 2022. It covered sociodemographic data, conditions associated with ocular irritation, and questions related to mask-wearing duration. The Ocular Surface Disease Index (OSDI) survey was used to measure DED severity. Binary logistic regression analysis was done and Odd's ratios (OR) with 95% confidence intervals (CI) were reported. RESULTS: A total of 266 female nurses responded to this study. The majority of the sample (71.1%) fell in the normal-mild DED category (OSDI 0-22), while (28.9%) were categorized as the moderate-severe DED category (OSDI >22). We found a significant independent association of dry eye disorder with wearing a mask for >6 hours/day (OR 2.066, 95% CI: 1.083-3.944). Other significant predictors of DED in this study were wearing corrective eyeglasses (OR 2.382, 95% CI: 1.296-4.376) and having rheumatoid arthritis (OR 17.289, 95% CI: 1.794-166.7). CONCLUSION: Wearing a face mask for > 6 hours/day was significantly associated with moderate to severe DED among female nursing staff. Ophthalmologists should be aware of this adverse effect in order to promote ways to relieve this condition.

Development of a novel ex vivo model for chemical ocular toxicity assessment and its applicability for hair straightening products.

This study developed an air-liquid interface (ALI) corneal model using explants bovine eyes for ocular toxicity assessment of ten chemicals and seven hair straightening mixtures. It was successfully maintained physiologically viable and normal for six days. Both eye damage (GHS cat. 1) and irritating (GHS cat. 2) chemicals induced corneal injury in our model. However, cat. 2 irritants triggered moderate damage when compared to cat. 1 agents, which induced a marked cytotoxicity profile. The mixtures were also able to trigger viability reduction associated with histopathological changes in the corneal tissues, especially when the exposure was via aerosol particles. Thus, the chemical exposure microenvironment simulation seemed to provide more reliable toxicological data. Moreover, mixture-induced corneal damage correlated with increased ROS levels, suggesting a close correlation between tissue death and oxidative stress. Besides mixtures showing the potential to induce moderate/mild ocular toxicity, we could verify that the corneal tissue damage showed reversibility due to the recovery from the injury after exposure to some of the mixtures. Hence, our ex vivo corneal model seems to be a simple and cost-effective approach for future studies related to further investigating the reversibility of damage in the cornea triggered by chemicals and their mixtures.

Ascorbic acid specifically reduces the misclassification of nonirritating reactive chemicals in the OptiSafe™ macromolecular eye irritation test.

Recently, we showed that the addition of physiological concentrations of ascorbic acid, a tear antioxidant, to the OptiSafe™ macromolecular eye irritation test reduced the false-positive (FP) rate for chemicals that had reactive chemistries, leading to the formation of reactive oxygen species (ROS) and molecular crosslinking. The purpose of the current study was to 1) increase the number of chemicals tested to comprehensibly determine whether the antioxidant-associated reduction in OD is specific to FP chemicals associated with ROS chemistries and 2) determine whether the addition of antioxidants interferes with the detection of true positive (TP) and true negative (TN) ocular irritants. We report that when ascorbic acid is added to the test reagents, retesting of FP chemicals with reactive chemistries show significantly reduced OD values (P < 0.05). Importantly, ascorbic acid had no significant effect on the OD values of TP or TN chemicals regardless of chemical reactivity. These findings suggest that supplementation of ascorbic acid in alternative ocular irritation tests may help improve the detection of TN for those commonly misclassified reactive chemicals.

Cellular viability and death biomarkers enables the evaluation of ocular irritation using the bovine corneal opacity and permeability assay.

The BCOP assay is used in the identification of chemicals that cause no ocular irritation or serious damage. However, this method has not been found to adequately discriminate between mild from moderate ocular irritation (category 2A/2B), based upon the animal data. In this study, we aimed to establish methods for discerning ocular irritation by chemicals. We used the BCOP assay and the fluorescence staining methods based on biomarkers for cellular viability and death. The potential for ocular irritation by 12 chemicals from different UN GHS categories was assessed by the BCOP assay. Cryosections of bovine corneas were obtained. The necrotic nucleus was TUNEL labeled, cytoplasmic f-actin was stained by phalloidin while the nucleus was stained by DAPI. The depth of injury (DOI) was then measured. According to BCOP assay, in vivo data of Draize eye test and DOI, the results showed that category NC irritants caused ≤ 10 % epithelial DOI, irritants of category 2B caused >10 % epithelial DOI and showed no stromal damage, while category 2A showed damage to the stroma. Based on these results, the GHS prediction model could distinguish between GHS 2A and 2B. Authenticating the viability of BCOP by DOI measurements can provide a more reliable basis for classifying ocular irritants.

Thermosensitive Poly(DHSe/PEG/PPG Urethane)-Based Hydrogel Extended Remdesivir Application in Ophthalmic Medication.

The spread of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the coronavirus disease 2019 (COVID-19) outbreak beginning in March 2020. Currently, there is a lack of suitable dose formulations that interrupt novel coronavirus transmission via corneal and conjunctival routes. In the present study, we developed and evaluated a thermosensitive gelling system based on a selenium-containing polymer for topical ocular continuous drug release. In detail, di-(1-hydroxylundecyl) selenide (DHSe), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) were polymerized to form poly(DHSe/PEG/PPG urethane). The polymer was used to carry poorly water-soluble remdesivir (RDV) at room temperature to form the final thermosensitive in situ gel, which exhibited a typical sol-gel transition at 35 °C. The formed polymer was further characterized by rheology, thermology, and scanning electron microscopy. In vitro release studies and in vivo retention and penetration tests indicated that the thermogel provided the prolonged release of RDV. The RDV-loaded in situ gel was proven to be non-biotoxic against human corneal epithelial cells, with good ocular tolerance and biocompatibility in rabbit eyes.

A microelectric cell sensing technique for in vitro assessment of ocular irritation.

The animal-based Draize test remains the gold standard for assessment of ocular irritation. However, subjective scoring methods, species differences, and animal welfare concerns have spurred development of alternative test methods. In this study, a novel in vitro method for assessing ocular irritancy was developed using a microelectric cell sensing technology, real-time cell analysis (RTCA). The cytotoxicity of sixteen compounds was assessed in two cell lines: ARPE-19 (human retina) and SIRC (rabbit cornea). In vitro inhibitory (IC50 and AUC50) values were determined at 6, 12, 24, 48, 72, and 96 h exposure, with a subset of values confirmed with MTT testing. The values displayed comparable predictivity of in vivo ocular irritation on the basis of a linear regression between the calculated values and each compounds' corresponding Draize-determined modified maximum average score (MMAS), but the ARPE-19 derived values were more strongly correlated than those from SIRC cells. Hence, IC50 values derived from ARPE-19 cells were used to predict the UN GHS/EU CLP classification of each test compound. The method was determined to have sensitivity of 90%, specificity of 50%, and overall concordance of 75%. Thus, RTCA testing may be best incorporated into a top-down tiered testing strategy for identification of ocular irritants in vitro.

Thiolated cyclodextrins: Mucoadhesive and permeation enhancing excipients for ocular drug delivery.

Thiolated ß-cyclodextrin (ß-CD) has the potential to enhance mucoadhesive and permeation enhancing properties on ocular mucosa. Thiolated ß-CD was synthesized via replacement of all primary hydroxyl groups on ß-CD backbone by halogen followed by substitution with thiol groups. The structure was confirmed by FT-IR and 1H NMR spectroscopy. Thiolated CD was characterized for hemolytic effect, ocular irritation, solubility enhancement, viscoelastic behavior and mucoadhesive properties. Moreover, the permeation enhancing effect of thiolated oligomer on different ocular tissues including conjunctiva, sclera and cornea was evaluated with sodium fluorescein (Na-Flu) as a marker. Thiolated ß-CD displayed 5360 ± 412 µmol/g thiol groups. The newly synthesized oligomer did not show any hemolytic effect on red blood cells at a concentration of 0.5% (m/v) for an incubation period of 3 h and minimal corneal irritation effects without any inflammation within 72 h. Thiolated ß-CD exhibited a 5.3-fold improved aqueous solubility as compared to the unmodified ß-CD. Thiolated oligomer (0.5% m/v) enhanced the viscosity of mucus up to 6.2-fold within 4 h and provided a 26-fold prolonged ocular residence time due to mucoadhesion. Moreover, 0.5% (m/v) thiolated ß-CD enhanced the permeation of Na-Flu 9.6-, 7.1- and 5.3-fold on conjunctiva, sclera and cornea, respectively. Based on these findings, thiolated ß-CD might be a promising auxiliary agent for ocular drug delivery.