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The influence of a cream containing 20% glycerin and its vehicle on skin barrier properties

  • Eviderm Institute

Abstract and Figures

Glycerin is widely used in cosmetics and well as in pharmaceutical formulations, mainly as humectant. In vitro studies have shown glycerin to prevent crystallization of stratum corneum model lipid mixture at low room humidity. Whether this may affect the skin barrier function during repeated application of glycerin in a cream base to normal skin is not known. Therefore, the influence of a cream containing 20% glycerin was compared with its placebo cream in a bilateral, double-blind study on 17 healthy volunteers. The effect was evaluated as influence on hydration with a corneometer and on skin barrier function. Skin barrier function was assessed as permeability to water with an evaporimeter (transepidermal water loss; TEWL) and as sensitivity to an irritating surfactant by measuring the biological response (measured as TEWL and skin blood flow). Ten days treatment of normal skin with 20% glycerin significantly increased skin corneometer values, indicating an increased hydration. However, our study failed to show an influence of glycerin on human skin, in terms of TEWL and skin sensitivity to SLS-induced irritation.
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Skin Research and Technology 2001; 7: 209–213
Copyright CMunksgaard 2001
Printed in Denmark. All rights reserved Skin Research and Technology
ISSN 0909-752X
Instrumental and dermatologist evaluation of the effect of
glycerine and urea on dry skin in atopic dermatitis
M. Lode
, A.-C. Andersson
, C. Andersson
, T. Frödin
, H. Öman
and M. Lindberg
ACO Hud AB, Stockholm,
Department of Dermatology, University Hospital, Uppsala,
Department of Dermatology,
Linköping University Hospital, Linköping,
Department of Medicin, Occupational Dermatology, Karolinska Institute, Stockholm, Sweden
Background/aims: Moisturising creams are useful treatment
adjuncts in inflammatory dermatoses and have beneficial effects
in the treatment of dry, scaly skin. The effects on dryness and
skin permeability of a new moisturising cream with 20% glycerine
was compared with its placebo and with a medicinally authorised
cream with 4% urea (combined with 4% sodium chloride) in the
treatment of dry skin.
Methods: Patients (
109) with atopic dermatitis were treated
for 30 days with a moisturiser in a randomised, parallel and
double-blind fashion. Transepidermal water loss (TEWL) and
skin capacitance were assessed instrumentally, and changes in
the dryness of the skin were assessed by the dermatologist.
Results: No difference in TEWL was found between glycerine
treatment and its placebo, whereas a lower value was found in
is a common, chronically relaps-
ing skin disorder, usually beginning in child-
hood. Moisturising creams are useful treatment ad-
juncts in such inflammatory dermatoses and have
beneficial effects in the treatment of dry, scaly skin
(1). However, although clinical experience suggests an
important role for moisturisers, more scientific studies
are considered essential to demonstrate possible dif-
ferences in mechanism and effect (2).
Moisturising creams occlude the skin and contain
humectants to increase its water content. Widely used
humectants are urea, lactic acid, PCA and glycerine.
Glycerine and urea diffuse into the stratum corneum
(3–5) and increase the water-holding capacity of nor-
mal stratum corneum and of scales from psoriatic and
ichthyotic patients (6–9). The humectants relieve clin-
ical signs of dryness, such as scaling (10–12), and
glycerine has also been shown to increase the rate of
corneocyte loss from the superficial surface of human
skin, probably due to an enhanced desmosome degra-
dation (13). Glycerine has also been proposed to in-
fluence the crystalline arrangement of the intercellular
bilayer lipids (14). The bulk of the bilamellar sheets of
the lipids has been suggested to be in crystalline/gel
the urea-treated area compared to the glycerine-treated area. No
difference in skin capacitance was found. The clinical assess-
ment of dryness showed urea to be superior to glycerine in treat-
ing the condition.
Conclusions: Moisturising creams are different, not only with
respect to composition but also with respect to their influence on
skin as a barrier to water in patients with atopic dermatitis.
Key words: moisturiser – dry skin – cream – emollient – per-
meability barrier – transepidermal water loss
Munksgaard, 2001
Accepted for publication 28 January 2001
domains bordered by lipids in a fluid crystalline state
(15). In dry skin, the proportion of lipids in the solid
state is suggested to be elevated, and glycerine may
then help to maintain the lipids in a liquid crystalline
state at low relative humidity (14).
The influence of glycerine on the intercellular lipids
may have consequences for the permeability of the
skin. Studies on normal skin show that a single appli-
cation of an aqueous solution of glycerine reduces
transepidermal water loss (TEWL) for some hours (6),
whereas repeated application of 20% glycerine in a
cream did not change TEWL or skin susceptibility to
sodium lauryl sulphate (SLS) in a placebo-controlled
study on normal skin (16). In tape-stripped and ace-
tone-treated skin, a single application has been shown
to decrease skin sensitivity to alkali, SLS and di-
methylsulfoxide, but to increase the bioavailability of
hexyl nicotinate (17). The other humectant, urea, has
been found to decrease TEWL in normal and dry skin
(8, 18–20) and to decrease skin sensitivity to SLS-in-
duced irritation (18, 19), but to be a penetration en-
hancer for some drugs (21–23).
Although moisturisers with various compositions
are used extensively on patients with atopic derma-
´n et al.
titis, controlled studies of their effects on dryness and
skin permeability are few. The aim of the present
study was to investigate the effect on dryness and
skin permeability of a 20% glycerine cream and its
placebo on patients with atopic dermatitis and to
compare the effect with an established cream contain-
ing urea (4%) and sodium chloride (4%). The effect
was judged by an expert (dermatologist) and meas-
ured as transepidermal water loss and skin capaci-
Material and Methods
The study was randomised, double-blind and per-
formed on three parallel groups in February to April
of the same year. In total, 110 patients (93 women and
16 men) with atopic dermatitis [according to criteria
of Hanfin & Rajka (24)], but with no other significant
concurrent illness and no known allergy to ingredi-
ents in the test creams, were included. One patient
dropped out.
The mean age the standard deviation (SD) was
3411 years in the glycerine group, 3413 years in
the urea group and 3311 years in the placebo group.
One area on the body was identified as dry by the
dermatologist and was treated twice daily for 30 days
with the cream. Among the 109 patients, the majority
(87 patients) treated one area on the upper or lower
forearm, 8 patients treated one area on the back, 8
treated the dorsal aspect of the hand and 6 treated one
area on the leg. The patients were asked to replace
their ordinary moisturiser by the test cream. The local
ethics committees approved the study, and informed
consent was obtained.
Test products
The glycerine cream contained 20% glycerine, aqua,
petrolatum, canola, mineral oil, cetearyl alcohol, gly-
ceryl stearate, dimethicone, PEG-100 stearate, glyceryl
polymethacrylate, cholesterol, propylene glycol,
methylparaben and propylparaben. Glycerine was re-
placed by water in the placebo cream. The urea cream
contained 4% urea and 4% sodium chloride as water-
binding substances in an oil-in-water emulsion, pH
about 5. Other ingredients were paraffinum liquidum,
PEG-5 glycerylstearate, cetyl alcohol, stearyl alcohol,
stearic acid, trometamol, methylparaben, propylpar-
aben, hydrochloric acid and water.
The expert assessment of severity of the dry skin was
done at the start of the study and after 30 days, ac-
cording to a newly proposed system for dry skin and
ichthyosis (25). Scaling, roughness, redness and cracks
(fissures) in the identified area were scored from 0 to
4, and the sum of the severity score was calculated
(maximum 16). The same expert evaluated the patient
at the start of and end of the study, and the evalu-
ations were performed in the same room and with the
same light conditions.
TEWL and skin capacitance were measured before
the first application of the creams (i.e., at day 0) and at
day 31. TEWL was quantified using an evaporimeter
(Servomed, Kinna, Sweden) (26). The probe is
equipped with a screen and grid to reduce air convec-
tion. The electrical capacitance, indicating degree of
skin hydration (27, 28), was measured with a Corneo-
meter CM-820 and CM-825 (Courage and Khazaka
GmbH, Cologne, Germany). During measurements,
noise and talk in the room were restricted. Measure-
ments were made in a temperature-controlled room.
Calculations and statistics
Side-by-side box-and-whisker plots are used to dis-
play the data. The box is defined by the upper and
lower quartiles and with the median marked by a sub-
division of the box. The whiskers have a maximum
length in terms of the interquartile range, and outliers
are shown (Minitab Statistical Software, Minitab Inc.,
State College, PA, USA). A Spearman rank correlation
(nonparametric) test was used to quantify the degree
of linear association between the change in TEWL and
the dryness score.
Statistical significances between the glycerine cream
and the other two treatments were tested using the
Mann-Whitney rank sum test. P0.025 was con-
Fig. 1. Skin barrier function measured as TEWL at the start of the
study and after 30 days of treatment with glycerine (n40), urea (n
35) and placebo (n34).
Evaluation of glycerine and urea in atopic dermatitis
sidered as significant for each of the two comparisons
to obtain an overall significance level of P0.05.
After treatment for 30 days, a significantly lower
TEWL was found in the area treated with urea com-
pared to the area treated with glycerine (P0.021)
(Fig. 1). No difference was found between the glycer-
ine treatment and the placebo treatment (P0.419). A
lower value of the dryness score was also found in
the area treated with urea compared to the area
treated with glycerine (P0.024), while no difference
was found between the glycerine-treated area and the
placebo-treated area (P0.419) (Fig. 2). One patient in
the glycerine group and four patients in the placebo
Fig. 2. Skin dryness severity score at the start of the study and after
treatment for 30 days with glycerine (n40), urea (n35) and placebo
Fig. 3. The mean value of the sum of the dryness severity score and
the mean value for the four parameters for dryness at the start of the
study and after treatment for 30 days with glycerine (n40), urea
(n35) and placebo (n34).
Fig. 4. Skin capacitance (A.U.) measured with a Corneometer at the
start of the study and after treatment for 30 days with glycerine (n
40), urea (n35) and placebo (n34).
Fig. 5. Multiple scatter plot displaying the relationship between the
change in TEWL and in dryness score (note: a positive change indi-
cates improved skin). Glycerine is plotted with the symbol A and urea
with the symbol B. If several points fall on the same spot, a count is
given. If the count is over 9, a πis used.
group showed more dryness after the treatment
period. No patient showed more dryness in the urea/
sodium chloride group.
The analysis of possible influences on the four
characteristics of dryness (scaling, roughness, redness
and cracks) showed no obvious difference on scaling
and roughness between the treatments (Fig. 3). How-
ever, glycerine might have had less influence on red-
ness and cracks than the other treatments. In six pa-
tients redness increased and in seven redness de-
creased during treatment with glycerine. In the pla-
cebo group, four patients showed an increased red-
ness, whereas no patients in the urea group showed
increased redness at the end of the study.
No difference in skin capacitance was detected at
day 31 between glycerine and urea, or between
´n et al.
glycerine and placebo, although the value tended to
be higher in the glycerine-treated area than in the pla-
cebo-treated area at day 31 (P0.076) (Fig. 4).
The association between the change in dryness
score and the change in TEWL was significant (r
0.332, P0.0004). The individual data from the areas
treated with glycerine and urea can be observed in a
multiple scatter plot (Fig. 5).
The relationship between degree of skin dryness and
TEWL is complex (29, 30). Elevated levels can be
found both in hyperhydrated (31) and in dry skin,
e.g., in atopic patients (32). The value is usually lowest
in normal appearing skin. However, a low value may
also be found in skin that appears to be dry, since
the major permeability barrier may be confined to the
lower part of the stratum corneum and the dryness to
the outermost stratum corneum (30) – i.e., the defects
can be localized at different depths of the stratum
corneum. Therefore, a change in the appearance of
dryness due to various treatments may not necess-
arily reflect a simultaneous change in TEWL.
In the present study, a significant relationship was
noted between the improvement in clinical signs of
dryness and reduction in TEWL. The clinical evalu-
ation of dryness showed the improvement from
glycerine treatment to be less pronounced compared
to the improvement from treatment with urea/so-
dium chloride. However, this was not supported by
the skin surface capacitance measurements, where no
difference between the two areas was detected. Nei-
ther could we observe a statistically significant in-
crease in capacitance in the glycerine-treated area
compared to its placebo, which is in contrast to a pre-
vious study on normal skin, where higher capacitance
levels were obtained after 10 days treatment (16).
However, in the study on normal skin, paired com-
parisons were made, which give less variability and
thus increases the possibility to detect statistically sig-
nificant differences. Moreover, data from corneometer
readings might be difficult to interpret. Corneometer
measurements are claimed to reflect the hydration sta-
tus of the skin, but can be influenced by other agents
than water – for instance, by body hair and cream
residues (33, 34). The active ingredients in the creams
tested, urea and glycerine, can also induce changes in
keratin dipole orientation and thereby affect the elec-
trical properties of the skin (28).
No evidence of deterioration of the permeability
barrier from glycerine treatment was found when
TEWL for glycerine-treated and placebo-treated skin
was compared, although glycerine has been proposed
to be able to influence the structure of the bilayer
lipids (14). A significantly lower TEWL was found in
the urea-treated skin, than in the glycerine-treated
skin. This is in accordance with previous findings
where TEWL was reduced by treatment with urea-
containing preparations, both in dry and in normal
skin (8, 18–20, 35), whereas several urea-free moisturi-
sers appear to cause no major changes in TEWL in dry
or in normal skin (16, 18, 36–38). Other ingredients in
topical preparations may also affect the skin barrier
function. Five of the excipients in the emulsions have
also been studied using non-invasive instruments,
and no deterioration in skin barrier function could be
detected following application of canola oil, petrol-
atum, stearic acid, glyceryl stearate or PEG-100 stear-
ate to normal and surfactant-irritated skin (39, 40). In-
stead, canola oil reduced the damage in surfactant-
irritated skin (40).
In conclusion, the chemical composition of
moisturising creams is highly variable. The differ-
ences will inevitably cause differences not only in the
hydrating power of the moisturisers but also in their
influence on the skin barrier function. The results in
the present study suggest that suitable formulations
containing urea might be superior to glycerine-con-
taining emulsions, if improvement in skin barrier
function in dry atopic skin is considered important.
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Marie Lode
Box 622
SE-194 26 Upplands Väsby
Tel: 46 8 6223651
Fax: 46 8 6223680
e-mail: marie.loden/
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The evolution of biotechnology revolutionized the modern era. The uses of plastic and plastic-based materials were widely accepted but due to its non-biodegradable nature the focus of research is getting shifted towards biodegradable material called biopolymer. Biopolymers are the polymers derived from biological origin with characteristic of getting degraded after its use in the normal environmental condition. Bacterial cellulose (BC) is one of the sustainable biopolymers which are biodegradable, biocompatible, and are obtained from fermentation. In this book chapter, we have discussed the two main methods to obtain BC, its biosynthesis, and its wide application with their relevant characteristic features.
In the work, we report a kind of novel highly transparent oil-in-water (O/W) HIPE gels stabilized solely by c-phycocyanin (CPC; an important biliprotein pigment), with a great potential to act as outstanding containers for heat or UV labile lipophilic bioactives. The CPC was solubilized in 6 M urea solution containing 40 wt% glycerol, in order to achieve the improved emulsification performance of the protein, as well as the transparency of the resultant HIPE gels through the refractive index (RI) matching between the aqueous and dispersed oil (dodacane) phases. Using 6 M urea containing 40 wt% glycerol as the aqueous phase, the transparent HIPE gels could be formed at the CPC concentration (c) as low as 0.1 wt%, and oil fractions in the range 0.6–0.86. In the protein-poor regime, e.g., c < 0.5 wt%, increasing the c led to a progressive decrease in emulsion size, as well as strengthening of gel network, while in the protein-rich regime (c = 0.5–1.0 wt%), the emulsion droplet and gel stiffness were independent of the c. The as-fabricated transparent HIPEs (gels) exhibited an outstanding oxidative protection to encapsulated β-carotene against degradation upon extensive heating or UV irradiation.
The excessive production of glycerol as a by-product in the biodiesel industry increased environmental problems due to issues related to storage and waste management. Therefore, the catalytic conversion of glycerol into value-added chemicals is of great interest. Using heterogeneous catalysis, we investigated the selective acetalization of glycerol to solketal (C6H12O3), an additive used in fuel production, using acetone in the presence of bimetallic oxide catalysts (Co3O4/SnO2). The catalytic materials were fully characterized using physical and chemical techniques such as nitrogen sorption (BET), power X-ray diffraction, (p-XRD), temperature-programmed desorption, (TPD-CO2 and TPD-NH3), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). An attempt to correlate the acidic sites to the catalyst activity was not successful. However, it is important to note that, the reaction gave conversions greater than 90% and maximum selectivity to the formation of the solketal. Optimum conditions were investigated and showed the most active catalyst to be Co3O4/SnO2 (75:25) with conversion above 90%. Catalyst stability evaluations showed that Co3O4/SnO2 (50:50) is very stable and can be recycled up to 6 catalytic cycles with minor catalyst loss.
Background: Antimicrobial ointments are topical products used for the treatment of common skin infections. Potency superiority between certain ointments and creams used in the treatment of skin infections has been a controversial subject among clinicians. Objective: This study was carried out to investigate the activities of some antimicrobial ointments on selected bacteria and fungi of clinical importance that caused skin infections. Methodos: Three brands of antibacterial; gentamicin, chloramphenicol, bactroban and two brands of antifungal ointments; nystatin and Whitefield's were evaluated by agar - cup diffusion method for their antimicrobial activity. Minimum inhibitory concentration, minimum bactericidal concentration and minimum fungicidal concentration of the ointments were determined. Kinetic study of bactroban on all the clinical isolates was evaluated to determine their efficacy within a specific time lag. Results: All the isolates ofPseudomonas aeruginosa were susceptible to bactroban while 4 of the 5 isolates ofStreptococcus pyogenes were resistant. Three of the five isolates of Staphylococcus aureus were susceptible to bactroban. Gentamicin had no activity on Pseudomonas aeruginosa while 4 of the 5 isolates of Streptococcus pyogenes were susceptible to gentamicin. Three of the 5 isolates of Staphylococcus aureus were susceptible to gentamicin and varied resistance were recorded for chloramphenicol and antifungal agents. The MIC''s values recorded for the antimicrobial ointments examined varied with respect to concentrations and composition. Bactroban and gentamicin gave the MIC's 20mg/mL - 2000mg/mL and 50mg/mL - 400mg/mL while the MIC's range 160mg/ mL - 400mg/mL, 100mg/mL -160mg/mL and 180mg/mL -200mg/mL were also recoded for chloramphenicol, nystatin and Whitefield's against the isolates concerned respectively. The MBC's and MFC's values recorded against the isolates doubled the values obtained from the MIC's. Kinetic studies showed various population reduction to zero at varied contact time for clinical isolates of bacterial and fungi exposed to bactroban. Conclusion: These findings elicited potency differences among the ointments tested on the selected clinical microbial isolates examined, this could be useful in the selection of antimicrobial ointments for the management of skin infections caused by the microorganisms tested and their closely related strains.
Context: Indonesia is the largest producer of edible bird's nest (EBN) in the world. Previous research proved that epidermal growth factor (EGF) was detected from edible bird's nest extract. EGF will increase the metabolism of skin cells and can lighten the skin EGF will increase the metabolism of skin cells and can lighten the skin. Aims: This research aimed to formulate and prove the lightening and the moisturizing effect of EBN cream on white mice. Materials and methods: The 28 mice were divided into four group treatment. EBN 40% were formulated into cream with two formula types: water in oil (W/O) and oil in water (O/W). Before the treatment, white mice were exposed to UVA radiation until skin color level was 4. For 14 days, white mice were treated and observed skin color level and moisture content by skin analyzer. Results: The skin color level was 1 on day 8 (O/W), on day 9 (W/O), on day 8 (positive control), and showed skin color level was 4 on day 14 (negative control). The average water content on day 14 was 53.70 ± 1.21 (O/W), 50.13 ± 1.39 (W/O), 53.88 ± 0.88 (positive control), and 21.48 ± 2.90 (negative control). Conclusion: No significant difference was observed in lightening effect (Sig. 0.495) and moisturizing effect (Sig. 0.564) between O/W cream and W/O creams. W/O cream has good adhesion and O/W cream has good dispersion.
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Bacterial cellulose (BC) can be produced by an agitated or static fermentation process in presence of suitable media. Groups of microorganisms such as fungi, bacteria, and algae are responsible for the synthesis of BC. Under agitated cultivation, BC yield is enhanced as compared to static cultivation. BC is pure cellulose, so it can easily interact with hydrophilic or hydrophobic biopolymers. In this review paper, we have discussed the preparation and characterization of BC reinforced biopolymer (polylactic acid, cellulosic fibers, agar, and Mater-Bi) based biocomposites and biopolymer (natural rubber, chitosan, polycaprolactone, hydroxyapatite) reinforced BC-based biocomposites related research carried out in last 2 decades. The high moisture content of BC results in reduced compatibility to most hydrophobic biopolymers as compared to hydrophilic biopolymers. Mechanical properties of BC before and after reinforcement were compared as it is important parameters in the production of green composites with targeted application in tissue engineering, wound dressing, dental implants, artificial blood vessels, surgical mesh, bone fillings, heart valve, and artificial cartilage. This review paper will help in exploring various applications of BC-based biocomposites in addition to several parameters that affect the production of BC.
Moisturizers are used to restore or to maintain a normal function of the stratum corneum (SC). Mostly they are used for the indication of so-called dry skin. Product testing of moisturizers is facilitated by the use of bioengineering devices for objective evaluation of treatment effects. Noninvasive measurements have the advantage of not interfering with the studied area, in contrast to biopsies. The use of multiple instruments also makes it possible to measure several features at one time, which will increase the confidence of the observation. Furthermore, the treated area can be studied repeatedly to monitor changes with time. Several instruments also detect subclinical (nonvisible) changes, which may facilitate understanding of the mechanism and distinguish between treatment effects. The benefit for the consumer may also be enhanced if the data correlate to a perceptible and clinically interesting change of the skin. When multiple variables are used, the critical ones should be identified and the procedure for how they were selected should be discussed (e.g., by reference to publications, guidelines, or recommendations by regulatory authorities). Consistency among multiple measures of the same attribute increases the confidence of the observation. This chapter is an effort to provide some information into how the performance of moisturizers can be objectively measured.
The combination of sodium chloride and urea in equal parts has shown a synergistic effect in regard to the water-retaining property of human skin. A cream with 4% sodium chloride and 4% urea, called 'salt cream' was tested in a double-blind investigation on asteatosis, with the symptoms dryness and scaling but without any inflammation, and showed a good clinical effect. There was a statistically higher significant difference (p<0.001) between the cream with sodium chloride and urea and the same cream but without these components. A second double-blind investigation was then made in order to evaluate the effect on inflammatory skin disorders - e.g., dry and scaly eczemas. Cortesal® (a cream with 4% sodium chloride, 4% urea and 0.5% hydrocortisone alcohol) was significantly better than a conventional hydrocortisone acetate cream 1%, on the symptoms dryness (p<0.01), erythema (p<0.05) and scaling (p<0.05) and equally good on itching and lichenification. The total effect, estimated by the doctor, was also in favour of Cortesal® (p<0.01).
The measurement of water in the SC has progressed from in vitro investigations, the results of which are important in understanding the mechanisms of binding and flux, to the more clinically relevant in vivo techniques. In particular, in vitro results have shown that the mechanism of water binding changes over the range of about 0.1 to 0.5 (w/w) water content. At low hydration, water is tightly bound to polar groups of SC constituents (i.e., proteins), while at higher hydration, lower energy water-water binding occurs. Similarly, water flux changes with hydration over the same range of water content due to changes in D, K(m), and dc/dx. Results from in vivo investigations have shown that water content of the SC increases continuously with increasing depth, again spanning the range from about 0.1 to 0.5 (w/w). Thus, the mechanisms of flux and binding discovered with in vitro techniques are relevant to in vivo tissue. Recent emphasis with in vivo techniques has been directed toward quantitative measurement of the SC water profile. With further sophistication, it should be possible to routinely measure SC hydration in the clinic and thereby relate dermatological disorders (i.e., psoriasis, ichthyosis, etc.) to altered mechanisms of water uptake and flux.
• Sixty patients with moderate to severe xerosis participated in a 21-day, randomized, double-blind, contralateral study for efficacy of a specially neutralized 12% lactate lotion compared with a 5% lactic acid lotion and a nonlactated emollient lotion. The severity of xerosis was evaluated on days 0, 7, 14, and 21 during treatment and on days 28 and 35 one and two weeks after treatment was discontinued. All three preparations significantly reduced the severity scores of xerosis. During the "regression" period after treatment was discontinued, patients receiving 12% lactate lotion, compared with those treated with nonlactated emollient lotion, had had significantly greater reductions in the severity scores of xerosis for the lateral calf area at days 28 and 35 and for total severity scores (combined mean differences for lateral, medial, and pretibial areas) at day 35. Compared with 5% lactic acid lotion, the 12% lactate lotion provided significantly greater reductions for total severity scores at days 28 and 35. (Arch Dermatol 1983;119:27-30)
The release characteristics of aqueous and oily creams (BP) containing urea up to concentrations of 10% have been studied. The results show that the urea has little influence on the ability of the formulation to release its active ingredient, in this case, hexyl nicotinate. The preparations were then assessed in an in vivo experiment by measuring the time of onset of erythema induced by the hexyl nicotinate. The urea influenced the time of onset of erythema, and a mechanism for its action is proposed.