Draize Rabbit Eye Test Research Articles

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.

Irritant toxicity and lectin content of different processed products of Pinelliae Rhizoma

The present study aims to investigate the correlation between irritant toxicity variation and lectin content variation during the processing of Pinelliae Rhizoma products and to explore the feasibility of Western blot as a method for the detection of lectin. We processed Pinelliae Rhizoma Praeparatum Cum Alumine, Pinelliae Rhizoma Praeparatum, and Pinelliae Rhizoma Praeparatumcum Zingibere et Alumine to different degrees and then analyzed their irritant toxicity via Draize rabbit eye test. Western blot was employed to determine the lectin content in Pinelliae Rhizoma products processed with different methods. The correlation between toxicity variation and lectin content variation was then analyzed. Different decoction pieces of Pinelliae Rhizoma were collected for the determination of lectin content. The three processed products of Pinelliae Rhizoma showed gradually decreased toxicity and lectin content as the processing continued. The decreasing trend of lectin content was consistent with that of irritant toxicity during processing, which indicated that the change in lectin content could reflect the trend of irritant toxicity. No band of lectin appeared in the Western blot of processed products of Pinelliae Rhizoma, which suggested that western blotting can be used for the detection of toxic lectin in the processed products of Pinelliae Rhizoma. Lectin should not be detected in the Pinelliae Rhizoma products processed according to the methods in the Chinese Pharmacopoeia.

Mechanistic-based non-animal assessment of eye toxicity: Inflammatory profile of human keratinocytes cells after exposure to eye damage/irritant agents

Eye toxicity is a mandatory parameter in human risk and safety evaluation for products including chemicals, pesticides, medicines and cosmetics. Historically, this endpoint has been evaluated using the Draize rabbit eye test, an in vivo model that was never formally validated. Due to advances in scientific knowledge, economic and ethical issues, non-animal methods based on mechanisms of toxicity are being developed and validated for increasing the capability of these models to predict eye toxicity. In this study, the Cytometric Bead Array (CBA) and ELISA assays were used to evaluate the inflammatory cytokine profile produced by HaCaT human keratinocytes after exposure to chemicals with different UN GHS eye toxicity classifications, aiming to stablish a correlation between inflammatory endpoints and eye toxicity (damage/irritation) potential. As a first step, cytotoxic profile of the chemicals, including 3 non-irritants and 10 eye toxicants (GHS Category 1, 2A and 2B), was evaluated after 24 h exposure using MTT assay and Inhibitory Concentration of 20% of cell viability (IC20) was calculated for each chemical. Then, the cells were exposed to these chemicals at IC20 for 24 h and supernatants and cell lysates were analyzed by CBA assay for quantification of the following cytokines: IL-6, IL-8, IL-10, IL-1β, TNF and IL-12p70. Regarding cytotoxicity evaluation, chemicals showed different cytotoxicity profiles and data demonstrated no correlation with their UN GHS classification. Among the cytokines evaluated, IL-1β production has changed after exposure and such alterations were confirmed by quantification employing ELISA method. The higher intracellular levels of IL-1β were found in GHS Category 1 chemicals, followed by Category 2A and 2B, while non irritants did not induce such increase. Thus, these findings show that IL-1β measurement, using HaCaT model, can be a considerable biomarker to identify chemicals according to their potential in promote eye toxicity, differentiating damage from irritation potential.

Controlled drug delivery for glaucoma therapy using montmorillonite/Eudragit microspheres as an ion-exchange carrier.

BackgroundGlaucoma is a serious eye disease that can lead to loss of vision. Unfortunately, effective treatments are limited by poor bioavailability of antiglaucoma medicine due to short residence time on the preocular surface.Materials and methodsTo solve this, we successfully prepared novel controlled-release ion-exchange microparticles to deliver betaxolol hydrochloride (BH). Montmorillonite/BH complex (Mt-BH) was prepared by acidification-intercalation, and this complex was encapsulated in microspheres (Mt-BH encapsulated microspheres [BMEMs]) by oil-in-oil emulsion–solvent evaporation method. The BH loaded into ion-exchange Mt was 47.45%±0.54%. After the encapsulation of Mt-BH into Eudragit microspheres, the encapsulation efficiency of BH into Eudragit microspheres was 94.35%±1.01% and BH loaded into Eudragit microspheres was 14.31%±0.47%.ResultsBoth Fourier transform infrared spectra and X-ray diffraction patterns indicated that BH was successfully intercalated into acid-Mt to form Mt-BH and then Mt-BH was encapsulated into Eudragit microspheres to obtain BMEMs. Interestingly, in vitro release duration of the prepared BMEMs was extended to 12 hours, which is longer than both of the BH solution (2.5 hours) and the conventional BH microspheres (5 hours). Moreover, BMEM exhibited lower toxicity than that of BH solution as shown by the results of cytotoxicity tests, chorioallantoic membrane-trypan blue staining, and Draize rabbit eye test. In addition, both in vivo and in vitro preocular retention capacity study of BMEMs showed a prolonged retention time. The pharmacodynamics showed that BMEMs could extend the drug duration of action.ConclusionThe developed BMEMs have the potential to be further applied as ocular drug delivery systems for the treatment of glaucoma.

Analysis of Draize eye irritation testing and its prediction by mining publicly available 2008-2014 REACH data.

SummaryPublic data from ECHA online dossiers on 9,801 substances encompassing 326,749 experimental key studies and additional information on classification and labeling were made computable. Eye irritation hazard, for which the rabbit Draize eye test still represents the reference method, was analyzed. Dossiers contained 9,782 Draize eye studies on 3,420 unique substances, indicating frequent retesting of substances. This allowed assessment of the test’s reproducibility based on all substances tested more than once. There was a 10% chance of a non-irritant evaluation after a prior severe-irritant result according to UN GHS classification criteria. The most reproducible outcomes were the results negative (94% reproducible) and severe eye irritant (73% reproducible).To evaluate whether other GHS categorizations predict eye irritation, we built a dataset of 5,629 substances (1,931 “irritant” and 3,698 “non-irritant”). The two best decision trees with up to three other GHS classifications resulted in balanced accuracies of 68% and 73%, i.e., in the rank order of the Draize rabbit eye test itself, but both use inhalation toxicity data (“May cause respiratory irritation”), which is not typically available.Next, a dataset of 929 substances with at least one Draize study was mapped to PubChem to compute chemical similarity using 2D conformational fingerprints and Tanimoto similarity. Using a minimum similarity of 0.7 and simple classification by the closest chemical neighbor resulted in balanced accuracy from 73% over 737 substances to 100% at a threshold of 0.975 over 41 substances. This represents a strong support of read-across and (Q)SAR approaches in this area.

Assessment of the eye irritation potential of chemicals: A comparison study between two test methods based on human 3D hemi-cornea models

We have recently developed two hemi-cornea models (Bartok et al., Toxicol in Vitro 29, 72, 2015; Zorn-Kruppa et al. PLoS One 9, e114181, 2014), which allow the correct prediction of eye irritation potential of chemicals according to the United Nations globally harmonized system of classification and labeling of chemicals (UN GHS). Both models comprise a multilayered epithelium and a stroma with embedded keratocytes in a collagenous matrix. These two models were compared, using a set of fourteen test chemicals. Their effects after 10 and 60minutes (min) exposure were assessed from the quantification of cell viability using the MTT reduction assay. The first approach separately quantifies the damage inflicted to the epithelium and the stroma. The second approach quantifies the depth of injury by recording cell death as a function of depth. The classification obtained by the two models was compared to the Draize rabbit eye test and an ex vivo model using rabbit cornea (Jester et al. Toxicol in Vitro. 24, 597–604, 2010). With a 60min exposure, both of our models are able to clearly differentiate UN GHS Category 1 and UN GHS Category 2 test chemicals.

Characterization of new eye drops with choline salicylate and assessment of their irritancy by in vitro short time exposure tests

The aim of our study was to examine the irritation potential of new eye drops containing 2% choline salicylate (CS) as an active pharmaceutical ingredient (API) and various polymers increasing eye drop viscosity (hydroxyethylcellulose, hydroxypropyl methylcellulose, methylcellulose, polyvinyl alcohol, polyvinylpyrrolidone). The standard method for assessing the potential of irritating substances has been the Draize rabbit eye test. However the European Centre for Validation of Alternative Methods and the Coordinating Committee for Validation of Alternative Methods recommend, short time exposure (STE) in vitro tests as an alternative method for assessing eye irritation. The eye irritation potential was determined using cytotoxicity test methods for rabbit corneal cell line (SIRC) after 5min exposure. The viability of cells was determined using two cytotoxicity assays: MTT and Neutral Red Uptake. According to the irritation rankings for the short time exposure test, all tested eye drops are classified as non-irritating (cell viability >70%).

Survey of ocular irritation predictive capacity using Chorioallantoic Membrane Vascular Assay (CAMVA) and Bovine Corneal Opacity and Permeability (BCOP) test historical data for 319 personal care products over fourteen years

The Chorioallantoic Membrane Vascular Assay (CAMVA) and Bovine Corneal Opacity and Permeability (BCOP) test are widely used to predict ocular irritation potential for consumer-use products. These in vitro assays do not require live animals, produce reliable predictive data for defined applicability domains compared to the Draize rabbit eye test, and are rapid and inexpensive. Data from 304 CAMVA and/or BCOP studies (319 formulations) were surveyed to determine the feasibility of predicting ocular irritation potential for various formulations. Hair shampoos, skin cleansers, and ethanol-based hair styling sprays were repeatedly predicted to be ocular irritants (accuracy rate=0.90–1.00), with skin cleanser and hair shampoo irritation largely dependent on surfactant species and concentration. Conversely, skin lotions/moisturizers and hair styling gels/lotions were repeatedly predicted to be non-irritants (accuracy rate=0.92 and 0.82, respectively). For hair shampoos, ethanol-based hair stylers, skin cleansers, and skin lotions/moisturizers, future ocular irritation testing (i.e., CAMVA/BCOP) can be nearly eliminated if new formulations are systematically compared to those previously tested using a defined decision tree. For other tested product categories, new formulations should continue to be evaluated in CAMVA/BCOP for ocular irritation potential because either the historical data exhibit significant variability (hair conditioners and mousses) or the historical sample size is too small to permit definitive conclusions (deodorants, make-up removers, massage oils, facial masks, body sprays, and other hair styling products). All decision tree conclusions should be made within a conservative weight-of-evidence context, considering the reported limitations of the BCOP test for alcohols, ketones, and solids.

HET-CAM test for determining the possible eye irritancy of pesticides

Agrochemicals and veterinary products must undergo numerous toxicological tests before registration. The use of animals in these studies is a controversial issue. The Draize eye irritation test is one of the most criticised methods because of the injuries inflicted on the test animals. Several in vitro methods have been used to investigate the toxicity of potential eye irritants with a view to replacing in vivo eye irritation testing. One of these alternative methods is the Hen's Egg Test--Chorioallantoic Membrane (HET-CAM) test. In the present studies comparative screening was performed with a set of agrochemicals to establish parallel data on in vitro (HET-CAM) and in vivo (Draize) results. The examined materials were: Totril (ioxynil), Omite 57 E (propargit), Actellic 50 EC (pyrimiphos-methyl), Stomp 330 EC (pendimethalin), Mospilan 3 EC (acetamiprid), Alirox 80 EC (EPTC), Match 050 EC (lufenuron), Nonit (dioctyl sulphosuccinate sodium), Perenal (haloxyfop-R methyl ester), Pyrinex 48 EC (chlorpyrifos). These experiments showed good correlation between results obtained by the HET-CAM test and those of the Draize rabbit eye test in most cases. The present form of the HET-CAM test can be proposed as a pre-screening method for the determination of eye irritative potential, therefore the number of test animals can be reduced and/or experimental animals can be replaced.

Assessing ocular irritation potential using a modified ex vivo rabbit eye test

We have evaluated the ocular irritancy potential of an unknown environmental contaminant, para-toluene sulfonic acid (pTSA), compared with that of known irritants, 5% sodium dodecyl sulfate (SDS) and 10% acetic acid (AA), using a simplified, ex vivo rabbit eye test modified to measure cytotoxicity as a mechanistic correlate to the Draize rabbit eye test. Rabbit eyes were obtained fresh within 24 hours from an abattoir and then exposed to 50 μL of test material. Eyes were then incubated intact for 3 hours or 1 day, and the corneas were removed, stained with calcein acetoxymethylester (AM)/ethidium homodimer (live/dead assay, Invitrogen Corp., Carlsbad, CA, USA), and evaluated by laser scanning confocal microscopy. The number of dead cells was then quantified and the difference was statistically compared. For corneas exposed to 1 ppm and 1% pTSA, there was no significant difference in the number of dead cells compared with water-exposed, control corneas at either 3 hours or 1 day after exposure. However, corneas exposed to 10% and 50% pTSA showed significantly increased (p < .0001) numbers of dead cells, averaging (mean ± standard deviation) 486 ± 133 and 1,052 ± 101 cells/field of view (460 × 460 μm). The level of cytotoxicity was comparable with that observed for 10% AA, which averaged 409 ± 142 cells/field of view. The data suggest that pTSA is an innocuous irritant at exposure levels environmentally encountered, but that higher concentrations (10% and above) might be considered a slight to mild irritant. We conclude that this modified ex vivo rabbit eye test using the live/dead assay may be a useful model for developing ocular irritation assays.

Human hemoglobin denaturation as an alternative to the draize test for predicting eye irritancy of surfactants

Purpose Quantification of eye irritancy has been a problem for both the consumer product industry and ophthalmic researchers because of the need to predict the toxic potential of preparations that may come into contact with the ocular surface. The Draize rabbit eye test has been used for 60 years in attempts to predict human ocular irritancy based on topical instillation of the potential irritant and subjective scoring of ocular inflammation by direct visualization of the rabbit eye. The inadequacies of the Draize test have led to efforts in several laboratories to develop alternatives. Methods We propose an alternative to the Draize eye irritation test, using human hemoglobin rather than bovine hemoglobin and studying the protein denaturation induced by potential irritants. Among the factors that affect eye irritation, protein denaturation has been reported as one of the most important factors that can result in corneal opacity. Human protein denaturation was measured as indicative of eye irritation. Results We studied different known irritant and non-irritant compounds to establish the predictability of the method. The compounds considered as irritants in vivo had the greatest effect in terms of decreased human hemoglobin absorbance. Conclusions The proposed method is able to easily differentiate between irritant and non-irritants products in an easy manner. The method is easy, rapid, economical, and provides enough information about the potential eye irritant action of different surfactants.

Extent of Corneal Injury as a Biomarker for Hazard Assessment and the Development of Alternative Models to the Draize Rabbit Eye Test

ABSTRACTWe have characterized 22 ocular irritants differing in type (surfactants, acid, alkali, bleaches, alcohol, aldehyde, acetone) and severity (slight to severe) by using the low-volume rabbit eye test. Ocular irritation was evaluated by 1) light microscopy to assess pathological changes, 2) in vivo confocal microscopy (CM) to quantify 4-dimensionally (x, y, z, and t) initial corneal injury and later responses in the same eye, and 3) laser scanning CM to quantify initial cell death. These studies revealed that regardless of the processes leading to injury, slight irritants injure the corneal epithelium, mild irritants injure the corneal epithelium and the superficial stroma, and moderate/severe irritants injure the epithelium, deep stroma, and at times the corneal endothelium. Furthermore, extent of initial corneal injury was shown to predict subsequent responses and final outcomes. These findings suggest that extent of corneal injury may be used as a basis for the development of alternative ocular irritation tests. To test the validity of this approach, we have used an ex vivo, rabbit cornea culture model to measure extent of corneal injury following exposure to ocular irritants. Data indicate that the extent of ex vivo corneal injury significantly correlate with the extent of initial injury measured previously in live animals. Overall, these findings indicate that extent of initial corneal injury can be used as a new “gold standard” for the continued refinement and ultimate replacement of the Draize rabbit eye Ocular Irritation Test.

A Study of the Relationship between Cornea Permeability and Eye Irritation Using Membrane-Interaction QSAR Analysis

A methodology termed membrane-interaction QSAR (MI-QSAR) analysis has been used to develop QSAR models to predict drug permeability coefficients across cornea and its component layers (epithelium, stroma, and endothelium). From a training set of 25 structurally diverse drugs, significant QSAR models are constructed and compared for the permeability of the cornea, epithelium, and stroma plus endothelium. Cornea permeability is found to depend on the measured distribution coefficient of the drug, the cohesive energy of the drug, the total potential energy of the drug-membrane "complex," and three other energy refinement descriptor terms. The endothelium may be a more important barrier in cornea permeation than the stroma. Moreover, an investigation of the correlation between cornea permeation and eye irritation is presented as an example of a cross study on different ADMET properties using MI-QSAR analysis. Thirteen structurally diverse drugs, whose molar-adjusted eye irritation scores (MES) have been measured using the Draize rabbit-eye test, were chosen as an eye irritation comparison set. A poor correlation (R(2) = 0.0232) between the MES measures and the predicted cornea permeability coefficients for the drugs in the eye irritation set suggests there is no significant relationship between eye irritation potency and the cornea permeability.

Assessment of the Eye Irritating Properties of Chemicals by Applying Alternatives to the Draize Rabbit Eye Test: The Use of QSARs and In Vitro Tests for the Classification of Eye Irritation

Huggins has reported on the current situation relating to the development of alternatives to the Draize eye irritation test with rabbits, and an ECVAM Working Group have reviewed the efforts needed in order to replace this animal test within the next 10 years by using the results of non-animal assessment methods. Our report reviews regulatory experience gained over the last 20 years with the EU chemicals notification procedure with respect to the assessment of eye lesions observed in Draize tests. The nature of eye lesions and their importance for classification and labelling of possible hazards to human eyes are evaluated and discussed, with a view to promoting the development of specific in vitro assays which are able to discriminate between eye damage, moderate eye irritation, and minor irritation effects which are completely reversible within a few days. Structural alerts for the prediction of eye irritation/corrosion hazards to be classified and labelled according to international classification criteria, are presented, which should be validated in accordance with internationally agreed (OECD) principles for (Q)SAR system validation. Physicochemical limit values for prediction of the absence of any eye irritation potential relevant for human health can make available a definition of the applicability domains of alternative methods developed for the replacement of the Draize eye irritation test.

Development of a Sensory Neuronal Cell Model for the Estimation of Mild Eye Irritation

In an attempt to improve the in vitro test strategy for the estimation of eye irritation, a neuronal cell model has been developed, with cells expressing vanilloid receptor type 1 (VR1) nociceptors. The currently accepted method for measuring eye irritancy is the ethically and scientifically criticised Draize rabbit eye test, despite the fact that alternative in vitro methods are available which have proved to be reliable and reproducible for predicting severe ocular toxicity. However, no alternative tests for measuring neuronal stimulation have yet been developed, and the prediction of eye irritation in the mild range is therefore insufficient. VR1 is a nociceptor localised in C-fibre neurons innervating the cornea and the surrounding tissue, and it responds to potentially damaging stimuli by releasing Ca2+ into the cytoplasm. As a sensory endpoint, [Ca2+]i was measured in VR1 transfected cells, as well as in control cells. Short-term cell cytotoxicity studies (cell membrane rupture and morphological divergence) were used to determine the non-corrosive concentrations of the test chemicals. Preliminary results indicated that hygiene products used daily may induce eye irritation via VR1 nociceptors. The lowest toxic concentration (0.025%) of liquid hand soap, as determined by morphologic divergences of cells, generated an 80% increase in [Ca2+]i over the basal [Ca2+]i in VR1 transfected cells, whereas the non-specific [Ca2+]i increased by 33%. Furthermore, all the endpoints studied indicated that shampoo for children was less active than shampoo for adults. If this method is successfully validated with standardised reference chemicals, the model could complete the test battery of in vitro alternatives, resulting in the saving of thousands of laboratory animals.

Prediction of Eye Irritation from Organic Chemicals Using Membrane-Interaction QSAR Analysis

Eye irritation potency of a compound or mixture has traditionally been evaluated using the Draize rabbit-eye test (Draize et al., 1944). In order to aid predictions of eye irritation and to explore possible corresponding mechanisms of eye irritation, a methodology termed "membrane-interaction QSAR analysis" (MI-QSAR) has been developed (Kulkarni and Hopfinger 1999). A set of Draize eye-irritation data established by the European Center for Ecotoxicology and Toxicology of Chemicals (ECETOC) (Bagley et al., 1992) was used as a structurally diverse training set in an MI-QSAR analysis. Significant QSAR models were constructed based primarily upon aqueous solvation-free energy of the solute and the strength of solute binding to a model phospholipid (DMPC) monolayer. The results demonstrate that inclusion of parameters to model membrane interactions of potentially irritating chemicals provides significantly better predictions of eye irritation for structurally diverse compounds than does modeling based solely on physiochemical properties of chemicals. The specific MI-QSAR models reported here are, in fact, close to the upper limit in both significance and robustness that can be expected for the variability inherent to the eye-irritation scores of the ECETOC training set. The MI-QSAR models can be used with high reliability to classify compounds of low- and high-predicted eye irritation scores. Thus, the models offer the opportunity to reduce animal testing for compounds predicted to fall into these two extreme eye-irritation score sets. The MI-QSAR paradigm may also be applicable to other toxicological endpoints, such as skin irritation, where interactions with cellular membranes are likely.

IN VITRO OCULAR IRRITATION TOXICITY STUDY OF SOME PESTICIDES

The use of animals in toxicological screening is a controversial issue. The Draize eye irritation test receives particular criticism because of the injuries inflicted on the test animals. In recent years various in vitro methods have been developed to replace the heavily criticised Draize rabbit eye test for irritation testing. One of the best-studied alternative methods is the Hen's Egg Test-Chorioallantoic Membrane (HET-CAM). In the present studies comparative screening was performed with a set of pesticides to establish parallel data on in vitro (HET-CAM) and in vivo (Draize) results. The tested pesticides included Arelon 500 FW (isoproturon), Banvel 480 (dicamba), Dikamin D (2.4 D), Karathane LC (dinocap), Ronstar (oxadiazon) and Modown 4 F (bifenox). In most cases a good correlation was found between the HET-CAM assessment and results of the Draize rabbit eye test. Although the current form of the HET-CAM test is a valuable prescreen method for predicting the ocular irritation potential of chemicals, and can be used for reducing the number of experimental animals, a number of technical problems must still be addressed before these systems can replace whole animal tests. The HET-CAM test can be a useful component of a battery of tests needed for replacing the Draize rabbit eye test.

A QSAR model for the eye irritation of cationic surfactants

A QSAR model for the eye irritation of cationic surfactants has been constructed using a dataset consisting of the maximum average scores (MAS—accordance to Draize) for 29 in vivo rabbit eye irritation tests on 19 different cationic surfactants. The parameters used were logP (log [octanol/water partition coefficient]) and molecular volume (to model the partition of the surfactants into the membranes of the eye), logCMC (log critical micelle concentration—a measure of the reactivity of the surfactants with the eye) together with surfactant concentration. The model was constructed using neural network analysis. MAS showed strongly positive, non-linear correlations with surfactant concentration and logCMC and a strongly negative, non-linear correlation with logP. The Pearson correlation between the actual and predicted values of MAS was 0.838 showing that around 70% (r 2=0.702) of the variance in the dataset is explained by the model. This value is consistent with levels of biological variability reported historically for the Draize rabbit eye test. The relationship provides a potentially useful prediction model for the eye irritation potential of new or untested cationic surfactants with physicochemical properties lying within the parameter space of the model.

The HET–CAM, a Useful In Vitro Assay for Assessing the Eye Irritation Properties of Cosmetic Formulations and Ingredients

One of the most important biological properties of consumer products, and also of many raw materials, is the local compatibility to mucous membranes. Until now standardized in vivo tests are accepted by public health authorities as valid to estimate the irritation potential of chemicals and suitable for the risk assessment. Nevertheless, the controversial discussion on animal tests, and particularly on the Draize rabbit eye test, is increasing in the public and scientific domain. Efforts have been made to validate proper and suitable in vitro tests in international cosmetics industries during the last decade. One of the most important in vitro tests is the HET–CAM, the h en's e gg t est on the c horio a llantoic m embrane of fertilized chicken eggs. In this paper, the efforts to establish the HET–CAM protocol and the defined prediction model (PM) used in the COLIPA (The European Cosmetic, Toiletry and Perfumery Association) study on alternatives to the Draize rabbit eye test are described. Furthermore, the HET–CAM test results of the finalized phase I of the above-mentioned study are discussed in detail. Prior to the COLIPA validation study, the HET–CAM was prevalidated with about 100 test substances covering a broad spectrum of chemical structures and physical appearances and representing the range of chemicals in the cosmetics industry. This prevalidation was performed with a stringent in-house agreement in one company to test each chemical in the HET–CAM before any requested animal test was done. There was a high concordance of the HET–CAM results with in vivo data of the Draize test, especially for slightly irritating test articles. Based on these promising data, the HET–CAM protocol was taken as the final standard operating procedure (SOP) in the international COLIPA validation study, testing 55 coded chemicals in four different laboratories. The HET–CAM has been established and proven to be a robust test with a good prediction of irritation potential. According to strict associations of well-defined irritation categories ( in vivo and in vitro), and with the concrete PM, the in vivo irritation potential of 29 out of 55 test articles (about 52%) were correctly predicted with the HET–CAM in at least three laboratories. This quality of prediction was of different success in the four categories of irritation severity. 90% of the slightly irritating chemicals but only 53% of the severely irritating articles were correctly predicted. The necessity to define a “gold standard” for validation purposes and the conflict with heterogeneous in vivo data were also pronounced this article. Here it is discussed, whether the evaluation of such heterogeneous responses and especially of persistent slight effects on the cornea can be done properly with additional data such as physicochemical data and biological information of the test substance.

A critical review of the assessment of eye irritation potential using the Draize rabbit eye test.

Traditionally, the eye irritation potential of substances and products has been assessed using the Draize eye test. While this procedure has been criticized in terms of its scientific validity and its ethical acceptability, it remains the only official, government-recognized procedure for predicting the irritant effect of substances in the eye. The relative absence of serious human accidents testifies to the success of the predictions. With the development of alternative non-animal procedures to replace the Draize test, the data generated in the Draize procedure are also being used as a 'gold standard' against which the performance of alternative procedures is measured. The major sources of variability are small group size and inability of existing scoring systems to reflect the complexities of the total in vivo response. In addition, the use of algorithms to simplify the in vivo data (for comparison with in vitro data) also misrepresents the in vivo data. Addressing the above issues would inevitably increase the use of animals. This would go against the general public demand for a reduction in the use of animals. Therefore the issue is to decide upon a simple parameter (for comparison with in vitro data) that encompasses the complexity of the irritation response and accurately reflects irritation without requiring the use of additional test animals. Such a parameter could be the recovery time. In addition, controlled human testing to benchmark the Draize data would be invaluable. The future use of Draize data in the validation of in vitro alternatives is undisputed, but the utility of these data will only be enhanced by a proper understanding of the shortcomings of the Draize test.