Alternative Methods for Skin Irritation Testing: The Current Status

1998 ◽  
Vol 26 (2) ◽  
pp. 195-211 ◽  
Author(s):  
Philip A. Botham ◽  
Lesley K. Earl ◽  
Julia H. Fentem ◽  
Roland Roguet ◽  
Johannes J.M. van de Sandt
Keyword(s):  
Prediction Model ◽  
Human Skin ◽  
Task Force ◽  
Skin Irritation ◽  
Alternative Methods ◽  
Current Status ◽  
In Vitro Tests ◽  
Structure Property ◽  
Test Protocol

The ECVAM Skin Irritation Task Force was established in November 1996, primarily to prepare a report on the current status of the development and validation of alternative tests for skin irritation and corrosion and, in particular, to identify any appropriate non-animal tests for predicting human skin irritation which were sufficiently well-developed to warrant ECVAM supporting their prevalidation/validation. The task force based its discussions around the proposed testing strategy for skin irritation/corrosion emanating from an OECD workshop held in January 1996. The following have been reviewed: a) structure-activity and structure-property relationships for skin corrosion and irritation; b) the use of pH and acid/alkaline reserve measurements in predicting skin corrosivity; c) in vitro tests for skin corrosion; d) in vitro tests for skin irritation (keratinocyte cultures, organ cultures, and reconstituted human skin models); and e) human patch tests for skin irritation. It was apparent that, although several promising candidate in vitro tests for skin irritation (for example, reconstituted human skin methods, and human and animal skin organ culture methods) were under development and evaluation, a test protocol, a preliminary prediction model and supporting data on different types of chemicals were only available for a method employing EpiDerm™. Thus, it is proposed that this EpiDerm test undergoes prevalidation during 1998. In addition, since it was felt preferable to be able to include other in vitro tests in such a prevalidation study, it is recommended that a “challenge” be set to anyone interested in taking part. This involves submitting data on ten test chemicals selected by the task force, obtained according to a standard protocol with a preliminary prediction model, for review by the task force by 31 May 1998.

The In Vitro Acute Skin Irritation of Chemicals: Optimisation of the EPISKIN Prediction Model within the Framework of the ECVAM Validation Process

2005 ◽  
Vol 33 (4) ◽  
pp. 329-349 ◽  
Author(s):  
José Cotovio ◽  
Marie-Hélène Grandidier ◽  
Pascal Portes ◽  
Roland Roguet ◽  
Gilles Rubinstenn
Keyword(s):  
Prediction Model ◽  
Mtt Assay ◽  
Skin Irritation ◽  
Membrane Damage ◽  
Clinical Signs ◽  
Alternative Methods ◽  
In Vitro Tests ◽  
Validation Process

In view of the increasing need to identify non-animal tests able to predict acute skin irritation of chemicals, the European Centre for the Validation of Alternative Methods (ECVAM) focused on the evaluation of appropriate in vitro models. In vitro tests should be capable of discriminating between irritant (I) chemicals (EU risk: R38) and non-irritant (NI) chemicals (EU risk: “no classification”). Since major in vivo skin irritation assays rely on visual scoring, it is still a challenge to correlate in vivo clinical signs with in vitro biochemical measurements. Being particularly suited to test raw materials or chemicals with a wide variety of physical properties, in vitro skin models resembling in vivo human skin were involved in prevalidation processes. Among many other factors, cytotoxicity is known to trigger irritation processes, and can therefore be a first common event for irritants. A refined protocol (protocol15min–18hours) for the EPISKIN model had been proposed for inclusion in the ECVAM formal validation study. A further improvement on this protocol, mainly based on a post-treatment incubation period of 42 hours (protocol15min–42hours), the optimised protocol, was applied to a set of 48 chemicals. The sensitivity, specificity and accuracy with the MTT assay-based prediction model (PM) were 85%, 78.6% and 81.3% respectively, with a low rate of false negatives (12%). The improved performance of this optimised protocol was confirmed by a higher robustness (homogeneity of individual responses) and a better discrimination between the I and NI classes. To improve the MTT viability-based PM, the release of a membrane damage marker, adenylate kinase (AK), and of cytokines IL-1α and IL-8 were also investigated. Combining these endpoints, a simple two-tiered strategy (TTS) was developed, with the MTT assay as the first, sort-out, stage. This resulted in a clear increase in sensitivity to 95%, and a fall in the false-positive rate (to 4.3%), thus demonstrating its usefulness as a “decision-making” tool. The optimised protocol proved, both by its higher performances and by its robustness, to be a good candidate for the validation process, as well as a potential alternative method for assessing acute skin irritation.

ECVAM's Activities in Validating Alternative Tests for Skin Corrosion and Irritation

2002 ◽  
Vol 30 (2_suppl) ◽  
pp. 61-67 ◽  
Author(s):  
Julia H. Fentem ◽  
Philip A. Botham
Keyword(s):  
Human Skin ◽  
Validation Study ◽  
Task Force ◽  
Skin Irritation ◽  
Test Method ◽  
Performance Criteria ◽  
In Vitro Tests ◽  
Rat Skin ◽  
Formal Validation

ECVAM has funded and managed validation studies on in vitro tests for skin corrosion, resulting in the validities of four in vitro tests being endorsed by the ECVAM Scientific Advisory Committee: the rat skin transcutaneous electrical resistance (TER) assay, two tests based on the use of commercial reconstituted human skin equivalents, EPISKIN™ and EpiDerm™, and another commercially-produced test, CORROSITEX®. In the European Union (EU), a new test method on skin corrosion (B.40), incorporating the rat skin TER and human skin model assays, was included in Annex V of Directive 67/548/EEC in mid-2000, thereby making the use of in vitro alternatives for skin corrosion testing of chemicals mandatory in the EU. At the recommendation of its Skin Irritation Task Force, ECVAM has funded prevalidation studies on five in vitro tests for acute skin irritation: EpiDerm, EPISKIN, PREDISKIN™, the pig-ear test, and the mouse-skin integrity function test (SIFT). However, none of the tests met the criteria (set by the Management Team for the studies) for inclusion in a large-scale formal validation study. Thus, to date, there are no validated in vitro tests for predicting the dermal irritancy of chemicals. Following further work on the EPISKIN, EpiDerm and SIFT test protocols and/or prediction models after the completion of the prevalidation studies, it appears that the modified tests could meet the performance criteria defined for progression to a validation study. This will now be assessed independently by the ECVAM Skin Irritation Task Force, with the objective of taking a decision before the end of 2002 on whether to conduct a formal validation study.

The ECVAM Workshops: A Critical Assessment of their Impact on the Development, Validation and Acceptance of Alternative Methods

2002 ◽  
Vol 30 (2_suppl) ◽  
pp. 151-165 ◽  
Author(s):  
Robert D. Combes
Keyword(s):  
State Of The Art ◽  
Substantial Effect ◽  
Alternative Methods ◽  
Current Status ◽  
In Vitro Tests ◽  
Regulatory Requirements ◽  
Safety Testing ◽  
Task Forces ◽  
Development And Validation

ECVAM initiated its workshop programme in 1994, to enable it to become well informed about the state of the art of non-animal test development and validation, and about the possible incorporation of alternatives into regulatory requirements for safety testing. Fifty-one such workshops had been held on specific topics, up to 2002. In these workshops, the current status of in vitro tests and their potential uses were reviewed and recommendations were made as to the best ways forward to progress and enhance the use of in vitro methods. Reports for 46 of these workshops have been published in ATLA. Most of the workshops focused on in vitro replacement methods, although an increasing number have dealt with reduction and refinement. The recommendations in the ECVAM workshops have been progressed further by: a) the formation of ECVAM task forces; b) the organisation of further workshops; c) the activities of scientific committees; d) the provision of earmarked research funding; and e) the conduct of validation studies. Examples of each of these activities are discussed. Some individual workshops are covered in more detail, and several recommendations that have so far not been acted on are also considered. The workshops and their reports have had a substantial effect on the development and implementation of alternative methods, and have been a major factor in contributing to the success of the first nine years of ECVAM's existence. It is strongly recommended that ECVAM continues to organise workshops and to publish their findings, and suggestions are made for topics for future workshops.

scholarly journals Review of skin irritation/corrosion hazards on the basis of human data: a regulatory perspective

2012 ◽  
Vol 5 (2) ◽  
pp. 98-104 ◽  
Author(s):  
David Basketter ◽  
Dagmar Jírova ◽  
Helena Kandárová
Keyword(s):  
Patch Test ◽  
Skin Irritation ◽  
Alternative Methods ◽  
Test Protocol ◽  
Rabbit Skin ◽  
Irritation Test ◽  
Skin Irritation Test

Abstract Regulatory classification of skin irritation has historically been based on rabbit data, however current toxicology processes are transitioning to in vitro alternatives. The in vitro assays have to provide sufficient level of sensitivity as well as specificity to be accepted as replacement methods for the existing in vivo assays. This is usually achieved by comparing the in vitro results to classifications obtained in animals. Significant drawback of this approach is that neither in vivo nor in vitro methods are calibrated against human hazard data and results obtained in these assays may not correspond to situation in human. The main objective of this review was to establish an extended database of substances classified according to their human hazard to serve for further development of alternative methods relevant to human health as well as resource for improved regulatory classification. The literature has been reviewed to assemble all the available information on the testing of substances in the human 4 h human patch test, which is the only standardized protocol in humans matching the exposure conditions of the regulatory accepted in vivo rabbit skin irritation test. A total of 81 substances tested according to the defined 4 h human patch test protocol were found and collated into a dataset together with their existing in vivo classifications published in the literature. While about 50% of the substances in the database are classified as irritating based on the rabbit skin test, on using the 4 h HPT test, less than 20% were identified as acutely irritant to human skin. Based on the presented data, it can be concluded that the rabbit skin irritation test largely over-predicts human responses for the evaluated chemicals. Correct classification of the acute skin irritation hazard will only be possible if newly developed in vitro toxicology methods will be calibrated to produce results relevant to man.

scholarly journals Formulations Based on Drug Loaded Aptamer-Conjugated Liposomes as a Viable Strategy for the Topical Treatment of Basal Cell Carcinoma—In Vitro Tests

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 866
Author(s):  
Anca N. Cadinoiu ◽  
Delia M. Rata ◽  
Leonard I. Atanase ◽  
Cosmin T. Mihai ◽  
Simona E. Bacaita ◽  
...  
Keyword(s):  
Basal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Basal Cell ◽  
Topical Treatment ◽  
Skin Irritation ◽  
In Vitro Tests ◽  
Liposomal Drug ◽  
Liposomal Formulations ◽  
As1411 Aptamer

Topical liposomal drug formulations containing AS1411-aptamer conjugated liposomes were designed to deliver in a sustained way the 5-fluorouracil to the tumor site but also to increase the compliance of patients with basal cell carcinoma. The 5-fluorouracil penetrability efficiency through the Strat-M membrane and the skin irritation potential of the obtained topical liposomal formulations were evaluated in vitro and the Korsmeyer Peppas equation was considered as the most appropriate to model the drug release. Additionally, the efficiency of cytostatic activity for targeted antitumor therapy and the hemolytic capacity were performed in vitro. The obtained results showed that the optimal liposomal formulation is a crosslinked gel based on sodium alginate and hyaluronic acid containing AS1411-aptamer conjugated liposomes loaded with 5-fluorouracil, which appeared to have favorable biosafety effects and may be used as a new therapeutic approach for the topical treatment of basal cell carcinoma.

Analogy Models for Prediction of Human Toxicity

1990 ◽  
Vol 18 (1_part_1) ◽  
pp. 103-116
Author(s):  
Sven Hellberg ◽  
Lennart Eriksson ◽  
Jörgen Jonsson ◽  
Fredrik Lindgren ◽  
Michael Sjöström ◽  
...  
Keyword(s):  
Human Subjects ◽  
Toxicity Testing ◽  
In Vitro Cytotoxicity ◽  
Alternative Methods ◽  
Laboratory Animals ◽  
In Vitro Tests ◽  
Human Toxicity ◽  
Efficient Data ◽  
Basal Cytotoxicity

Estimating the toxicity to humans of chemicals by testing on human subjects is not considered to be ethically acceptable, and toxicity testing on laboratory animals is also questionable. Therefore, there is a need for alternative methods that will give estimates of various aspects of human toxicity. Batteries of in vitro tests, together with physicochemical and toxicokinetic data, analysed by efficient data analytical methods, may enable analogy models to be constructed that can predict human toxicity. It may be possible to model non-specific toxicity relating to lipophilicity, or basal cytotoxicity, for a series of diverse compounds with large variation in chemical structure and physicochemical properties. However, local models for a series of similar compounds are generally expected to be more accurate, as well as being capable of modelling more-specific interactions. Analogy models for the prediction of human toxicity are discussed and exemplified with physicochemical and cytotoxicity data from the first ten chemicals in the multicenter evaluation of in vitro cytotoxicity (MEIC) project.

CURRENT STATUS OF COMBINED ANTIBIOTIC THERAPY

PEDIATRICS ◽  
1958 ◽  
Vol 21 (6) ◽  
pp. 1000-1009
Author(s):  
Charles V. Pryles
Keyword(s):  
Synergistic Effect ◽  
Bacterial Resistance ◽  
Current Status ◽  
Causative Organism ◽  
In Vitro Tests ◽  
Aminosalicylic Acid ◽  
Tract Infections ◽  
Vitro Effect ◽  
Group 1

The use of combinations of drugs in "shotgun" fashion, on the theory if one will do something, two or three will accomplish more, is to be deplored. A single antibiotic can be used effectively in most infections caused by a single organism. Furthermore, a single wide-spectrum antibiotic may be used in many mixed infections. In certain infections, the value of combinations of antibiotics has been proved, both in the laboratory and in the clinic: (a) streptomycin plus one of the tetracyclines in brucellosis; (b) penicillin plus streptomycin in enterococcic endocarditis; (c) erythromycin plus chloramphenicol in serious staphylococcal infections in which the organism is resistant to penicillin; (d) streptomycin, isoniazid and para-aminosalicyclic acid in treatment of tuberculosis. In these infections, the proper combination should be used from the start and in full therapeutic dosage. Mixtures of antibiotics may occasionally be useful in individual cases outside this group but, in general, these mixtures do not produce a synergistic effect. If the infection does not fall into one of the four classes already cited, the in-vitro effect of combinations of various antibiotics should be studied, providing the patient's illness is such that a delay of 48 to 72 hours is warranted. The combination showing the greatest synergistic effect should then be used. Persisting urinary tract infections and endocarditis are examples of conditions in which this method is likely to produce results. Even here, it must be borne in mind that such in-vitro tests do not guarantee that a certain mixture of antibiotics will be effective clinically; in fact, they may be misleading. In accord with the recommendations of Dowling, if there is not sufficient time for an in-vitro study to be carried out, two antibiotics in Jawetz and Gunnison's Group 1 (see text) may be used together, if each alone is partially effective against the causative organism. If no two antibiotics in Group 1 fit this criterion, and a combination of an antibiotic from Group 1 and one from Group 2 does fit the criterion, this combination should be given in doses that will result in full therapeutic concentrations of each antibiotic at the site of infection. For delaying the emergence of resistant strains of tubercle bacilli, combinations of two or more of the following drugs are indicated: Streptomycin, isoniazid and para-aminosalicylic acid. A combination of chloramphenicol with erythromycin is also indicated to delay emergence of resistance of staphylococci to the batter antibiotics. In the treatment of seriously ill patients before a bacteriologic diagnosis is available, two or more antibiotics may properly be administered. Such illnesses include endocarditis, suspected staphylococcal pneumonia in infants, tuberculosis, brucellosis, and meningitis due to an unidentified organism. Combined antimicrobials should be given only after a careful clinical diagnosis has been made, and in doses that would be optimal for each drug if used alone. Readymade mixtures are not recommended for use systemically; certain combinations of agents, such as a mixture of bacitracin and polymyxin B, may have a place in topical therapy. Finally, there are several potentially harmful or undesirable effects that may result from the use of combinations of antimicrobials and these must be considered whenever their possible use arises. These include: (1) the tendency of fixed, "packaged" combinations to encourage inadequate therapy; (2) the possible increase in hypersensitivity and/or toxicity to one or more of the agents in a combination; (3) the probable emergence of bacterial resistance to either or both of the antibiotics in a mixture; (4) superinfection by originally resistant organisms not affected by the therapy; (5) the accumulation of antibiotic-resistant organisms within hospitals or other semiclosed communities; and (6) the possibility of interference of one antibiotic with the operation of another in a given combination.

Follow-up to the ECVAM Prevalidation Study on In Vitro Tests for Acute Skin Irritation

2002 ◽  
Vol 30 (1) ◽  
pp. 109-129 ◽  
Author(s):  
Valérie Zuang ◽  
Michael Balls ◽  
Philip A. Botham ◽  
Alain Coquette ◽  
Emanuela Corsini ◽  
...  
Keyword(s):  
Skin Irritation ◽  
In Vitro Tests

Development of Potential Alternatives to the Draize Eye Test: The CTFA Evaluation of Alternatives Program. Phase II: Review of Materials and Methods

1992 ◽  
Vol 20 (1) ◽  
pp. 164-171
Author(s):  
Stephen D. Gettings ◽  
Daniel M. Bagley ◽  
Michael Chudkowski ◽  
Janis L. Demetrullas ◽  
Louis C. DiPasquale ◽  
...  
Keyword(s):  
Animal Welfare ◽  
Phase Ii ◽  
Task Force ◽  
Alternative Methods ◽  
Personal Care ◽  
In Vitro Methods ◽  
Ocular Irritation ◽  
Member Company ◽  
Sole Criterion

The CTFA Evaluation of Alternatives Program is a multi-year effort, organised by the CTFA Animal Welfare Task Force, designed to evaluate the performance of currently promising in vitro (alternative) methods to the Draize eye irritancy test. The sole criterion for inclusion of a particular test is that it shows some initial promise as an alternative to the Draize eye test, and that it is under evaluation or development by a participating CTFA member company. Tests are evaluated for their ability to rank and discriminate the ocular irritation potential of prototype cosmetic and personal care formulations compared to the Draize eye test. Test materials and in vitro methods currently under evaluation in Phase II of the CTFA Program are described. Additional tests may be included in subsequent phases of the Program, should it be determined that they show particular promise as replacements for specific types of formulation. Conversely (at the discretion of sponsors), tests may be removed from the Program should initial promise be unfulfilled.

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