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Appendix C
Evaluations of Barrier Creamsi
Howard I. Maibach and Hongbo Zhai
IN VITRO DATA
In vitro studies test the effects of barrier creams on the skin, which
mimics the reaction of in viva skin. The in vitro method provides not only
qualitative data (i.e., distinguishes between the creams) but also quantita-
tive data (i.e., differences in absorption). Langford (1978) conducted in
vitro studies to determine the behavior of a formulated fluorochemical-
resin complex and a number of other solvents. He tested penetration
through treated filter paper, repellency on treated pigskin, and penetra-
tion of radio-labeled sodium lauryl sulfate through treated hairless mouse
skin. The fluorochemical-resin complex provided the best resistance
against a range of solvents.
Reiner et al. (1982) studied the protective effect of model ointments
on guinea pig skin in vitro. The permeation values of a toxic agent through
unprotected and protected skin within 10 hours as a function of time were
determined radiologically and enzymatically. Permeation of the toxic
agent was markedly reduced by ointments with a polyethylene glycol
base and ointments containing active substances.
Loden (1986) evaluated the effects of barrier creams on the absorption
of (l3H)-water (l4C)-benzene and (l4C)-formaldehyde by excised human
1The following material was prepared for the use of the principal investigators of this
study. The opinions and conclusions herein are the authors' and not necessarily those of the
National Research Council.
217
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218
STRATEGIES TO PROTECT THE HEALTH OF DEPLOYED U.S. FORCES
skin. The control skins and treated skins were exposed to the test sub-
stance for 30 minutes, and the amount absorbed was determined. The
model experimental "water barrier" cream reduced the absorption of
water and benzene but not formaldehyde. Only one cream slightly re-
duced the absorption of benzene and formaldehyde; the others did not.
Fullerton and Menne (1995) tested the protective effect of ethylene-
diaminetetraacetate barrier gels against nickel contact allergy in in vitro
and in viva studies. In an in vitro study, about 30 mg of barrier gel was
applied on the epidermal side of the skin and a nickel disc applied. After
24 hours, the disc was removed, the epidermis was separated from the
dermis, and the nickel content in the epidermis and dermis was quanti-
fied by adsorption differential pulse voltammetry. The amount of nickel
in the epidermal skin layer on treated skins was significantly less than the
amount in untreated skins.
Zhai et al. (1999) used an in vitro diffusion system to measure the
protective effect of quaternium-18 bentonite gels to prevent 1 percent
concentration of [35S] sodium lauryl sulfate penetration in human
cadaver skin. The accumulated amount in receptor cell fluid was mea-
sured to evaluate the model gels over 24 hours. The test gels significantly
decreased absorption when compared to the control samples of unpro-
tected skin.
Treffel et al. (1994) measured the effectiveness on human skin of
barrier creams against dyes (eosin, methylviolet, and oil red O) with
varying n-octanol/water partition coefficients (0.19, 29.8 and 165, respec-
tively). Barrier cream effects were assayed by measuring the dyes in the
epidermis of protected skin samples after 30 minutes. They found no
correlation between the galenic (pharmaceutic) parameters of the assayed
products and the protection level, indicating that neither the water con-
tent nor the consistency of the formulations affected the level of protec-
tion. This physicochemical data could be used for tailoring barrier creams
to meet the challenges of specific chemical agents.
IN VIVO DATA
Mahmoud and Lachapelle (1985) and Lachapelle et al. (1990) used a
guinea pig model to evaluate the protective value of barrier creams and/or
gels by laser Doppler flowmetry (blood flow) and histological assess-
ment. The histopathological damage after 10 minutes of contact to tolu-
ene was mainly confined to the epidermis; the dermis was almost normal.
Dermal blood flow changes were relatively high on the control site com-
pared to the sites pretreated with gel. In addition, the blood concentra-
tions of n-hexane in the control group and the gel-pretreated group were
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APPENDIX C
219
determined. It was possible to correlate results found by invasive (blood
levels) and noninvasive techniques.
Frosch et al. (1993a, 1993b, 1993c), and Frosch and Kurte (1994) devel-
oped the repetitive irritation test in the guinea pig and in humans to
evaluate barrier creams using a series bioengineering techniques. The
pretreated and untreated test skin (guinea pig or human) was exposed
daily to the irritants for two weeks. The resulting irritation was scored on
a visual scale and assessed by biophysical (bioengineering) techniques.
Some test creams suppressed irritation with all test parameters; some
showed no effect, and even increased irritation.
Zhai and Maibach (1996) used an in viva human model to measure the
effectiveness of barrier creams against dye indicator solutions, methylene
blue in water and oil red O in ethanol, representative of model hydrophilic
and lipophilic compounds. Solutions of 5 percent methylene blue and
5 percent oil red O were applied to untreated and barrier-cream pre-
treated skin with the aid of aluminum occlusive chambers, for either a
few minutes or four hours. At the end of the application time, the materi-
als were removed and consecutive skin surface biopsies were taken. The
amount of dye that had penetrated into each strip was determined by
calorimetry. Two model creams were effective; one increased the cumula-
tive amount of dye.
References
Frosch, P.J., A. Kurte, and B. Pilz, 1993a. Efficacy of skin barrier creams. 3. The repetitive
irritation test (RIT) in humans. Contact Dermatitis 29: 113-118.
Frosch, P.J., A. Schultze-Dirks, M. Hoffmann, I. Axthelm, and A. Kurte. 1993b. Efficacy of
skin barrier creams. 2. Ineffectiveness of a popular "skin protector" against various
irritants in the repetitive irritation test in the guinea pig. Contact Dermatitis 29: 74-77.
Frosch, P.J., A. Kurte, and B. Pilz. 1993c. Biophysical Techniques for the Evaluation of Skin
Protective Creams. Pp. 214-222 in Noninvasive Methods for the Quantification of Skin
Functions. P.J. Frosch and A.M. Kligman, eds. Berlin: Springer-Verlag.
Frosch, P.J., and A. Kurte. 1994. Efficacy of skin barrier creams. 4. The repetitive irritation
test (RIT) with a set of four standard irritants. Contact Dermatitis 31: 161-168.
Fullerton, A., and T. Menne. 1995. In vitro and in vivo evaluation of the effect of barrier gels
in nickel contact allergy. Contact Dermatitis 32: 100-106.
Lachapelle J.M., H. Nouaigui, and L. Mavot. 1990. Experimental study of the effects of a
new protective cream against skin irritation provoked by the organic solvents
n-hexane, trichloethylene and toluene. Dermatosen Beruf Umwelt 38: 19-23.
Langford, N.P. 1978. Fluorochemical resin complexes for use in solvent repellent hand
creams. American Industrial Hygiene Association Journal 39: 33-40.
Loden, M. 1986. The effect of four barrier creams on the absorption of water, benzene, and
formaldehyde into excised human skin. Contact Dermatitis 14: 292-296.
Mahmoud, G., and J.M. Lachapelle.1985. Evaluation of the protective value of an antisolvent
gel by laser Doppler flowmetry and histology. Contact Dermatitis 13: 14-19.
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STRATEGIES TO PROTECT THE HEALTH OF DEPLOYED U.S. FORCES
Reiner, R., K. Rossmann, C.V. van Hooidonk, B.I. Cuelen, and J.Bock. 1982. Ointments for
the protection against organophosphate poisoning. Arzneimittelforschung 32: 630-633.
Treffel, P., B. Gabard, and R. Juch. 1994. Evaluation of barrier creams: an in vitro technique
on human skin. Acta Dermatologica Venereolica 74: 7-11.
Zhai, H., and H.I. Maibach. 1996. Effect of barrier creams: human skin in vivo. Contact
Dermatitis 35: 92-96.
Zhai, H., D.J. Buddrus, A.A. Schultz, R.C. Wester, T. Hartway, S. Serianzana, and H.I.
Maibach. 1999. In vitro percutaneous absorption of sodium lauryl sulfate in human skin
decreased by quaternium-18 bentonite gels. In Vitro Molecular Toxicology 12: 11-15.
Representative terms from entire chapter:
guinea pig
