Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Use of a buffer to prevent Candida albicans infections on the skin.
The present application relates to using a substance capable of buffering
within the
pH range 2.0 - 5.5, for preparing a skin-occlusive or mucous membrane-
occlusive
article for preventing skin irritations and lesions caused by Candida
albicans. Ex-
amples of such articles are absorbent articles, such as diapers and sanitary
napkins,
wound dressings, such as bandages surgical tapes and plasters, gloves,
prostheses
and indwelling catheters.
Introduction
Infections caused by Candida albicans may constitute a major problem in connec-
tion with using skin-occlusive, mucous membrane-occlusive and absorbent
articles
such as diapers, pantyliners, sanitary napkins and wound dressings. Candida
albi-
cans has been found to correlate with severity of diaper dermatitis (Benjamin
L, Pe-
diatrician 1987, suppl. 1, p. 21 - 26). There are investigators that give C.
Albicans a
primary causative role in some expressions of diaper dermatitis (Leyden J and
Kligman AM, Arch. Dermatol. 1978, vol 114, p. 56 - 59).
pH appears to be a major source of confusion and contradiction in the context
of
Candida ecology. Candida carriage in vivo can occur readily over a broad range
of
pH. pH may be a factor of significance in the pathological status of C.
albicans in
vivo, but it does not exert its influence by affecting growth of the fungus,
i.e. the
rate of increase of its biomass (Odds FC, Candida and Candidosis. A review and
,~25 bibliography. 2°d ed. 1988, Bailliere Tindall). Dimorphism, the
ability of G albi-
cans to exist in a blastospore and a filamentous form, is reported to be
influenced by
pH (Buffo et al., Mycopathologia, vol. 85 (1984), p. 21-30; Odds (1988),
supra).
The blastospore form is favoured by slightly acidic pH and the filamentous
form at
neutral pH or above. Furthermore, it has been shown that microfilaments play
an
important role during pH-regulated morphological transition (Yokoyama et al.,
Mi-
crobiology, vol. 140 ( 1994), p. 281-287). Clinical observations of diabetic
patients,
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where a higher skin surface pH is possibly correlated to candidal intertrigo,
have
been reported (Yosipovitch et al., Diabetes Care, vol. 16 (1993), p. 560-563).
As already mentioned, there is often a risk for infections, skin irritations
and lesions
when covering the skin or mucous membranes with absorbent articles, wound
S dressings, plasters, gloves, prostheses and like articles. WO 98/57677 and
EP 0 202
126 both disclose that a neutral or a slightly alkaline pH in connection with
using
absorbent articles may lead to skin irritation and problems with odorous
substances.
According to the documents these problems are caused by lipases and
proteinases
present on the skin and the problems can be overcome by decreasing the pH of
the
absorbent article. The documents do not give any particular information about
problems caused by Candida or how to reduce the virulence of Candida albicans.
Summary of the invention
Now it has turned out that the virulence capability of Candida albicans can be
sub-
stantially impaired by decreasing pH of a skin-occlusive or mucous membrane-
occlusive article to a value within the range from 2.0 to 5.5. Thus a skin-
occlusive
or mucous membrane-occlusive article such as an absorbent article (a diaper, a
sanitary napkin, a pantyliner or a wound dressing, such as a bandage), a
plaster, a
surgical tape, said article containing a pharmaceutically acceptable non-toxic
and
non-irritating substance capable of buffering within the pH range 2:0 - 5.5,
is used
to for preventing skin irritations and lesions caused by Candida albicans.
Detailed description of the invention
Accordingly, the present invention relates to using an ingredient capable of
buffer-
ing within the pH range 2.0 - 5.5, for preparing a skin-occlusive article for
prevent-
ing skin irritations and lesions caused by Candida albicans. Any
pharmaceutically
acceptable, non-toxic and non-irritating ingredient capable of buffering
within the
specified range can be used. Examples of suitable buffering ingredients are
superab-
sorbent particles showing a level of neutralisation within the range of 20 -
50 %,
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and pharmaceutically acceptable, non-toxic and non-irritating buffering
solutions,
such as organic salt buffering solutions, for example an acetate buffer or a
citrate
buffer. The buffering solution can be directly added to the skin-occlusive or
mucous
membrane-occlusive article. Alternatively, a pharmaceutically acceptable gel
con-
s taming the buffering solution can be added. Examples of suitable gels
include gels
normally used for pharmaceutical purposes, such as agarose.
An acid buffering substance according to the present invention is added to a
skin-
occlusive article. As disclosed herein, the terms "skin-occlusive article" or
"mucous
membrane-occlusive article" relates to an article, which is intended to cover
the skin
or mucous membranes of a person. A skin-occlusive article or mucous membrane-
occlusive article according to the present invention can be an absorbent
article, such
as a diaper, a sanitary napkin, a pantyliner or a wound dressing, a surgical
tape, a
plaster. gloves, prostheses or indwelling catheters. It is not critical for
the invention
how the acid buffering substance is added, and accordingly it can be added to
the
skin-occlusive article in many different ways. Examples of suitable methods
for
adding the acid buffering substance to the skin occlusive article are
administration
of a solution containing the acid buffering substance, or administration of
said sub-
stance as a powder or gel. The administration can be carried out in connection
with
manufacturing said article or after said article has been manufactured.
As disclosed herein, the term "pharmaceutically acceptable antifungal agent"
relates
to compounds normally used to treat Candida infections, such as imidazole
deriva-
tives, nystatin and ciclopirox olamine. These compounds are added to the skin-
occlusive or mucous membrane-occlusive article in amounts corresponding to com-
mon therapeutical doses.
The present invention will now be described with reference to the enclosed
figures
and tables, in which:
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Figure 1 shows an example of a diaper to which an acid buffering substance can
be
added in accordance with the invention;
Figure 2 discloses the natural distribution of skin surface pH on volar
forearms in 15
females. The observations are mean values of left and right arm;
Figure 3 presents a diagram showing pH development of patch sites before,
during
and after wearing a patch buffered with an acid buffering substance and a
regular
reference patch;
Table I presents results from visual assessment of skin reaction to Candida
albicans
infection; and
Table II shows growth of Candida albicans 24 hours after inoculation.
The diaper 100 disclosed in figure 1 comprises a liquid-permeable outer layer
1, for
example made of a fibre fabric or a perforated plastic film, a liquid-
impermeable
outer layer 2, for example made of a plastic film or a hydrophobic fibre
fabric, and
finally an absorbent body 3 enclosed between the outer layers 1, 2.
The diaper is intended to surround the lower part of the trunk of the wearer
like a
pair of absorbing pants. It is therefore designed with two end parts 4, 5 as
well as a
narrower crutch part 6 between the end parts, which when the diaper is used is
in-
tended to be arranged in the crutch of the wearer between the legs. In order
to obtain
the desired pant design, adhesive flaps 7 are arranged close to the rear waist
edge 8.
Upon use, the adhesive flaps are fastened to the front part 5 of the diaper,
close to
the front waist edge 9, in order to hold the diaper together around the waist
of the
wearer.
Moreover, the diaper according to figure 1 comprises pretightened elastic
means 10,
which may consist of elastic strings, elastic threads, elastic foam or another
suitable
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material. The elastic means 10 are, for the sake simplicity, shown in
outstreched
condition. However, as soon as the stretching ceases they contract and form
elastic
bands in the diaper.
The absorbent body 3 in the example shown in figure 1 is formed by two layers
11,12, an upper liquid-receiving layer 1 l and a lower layer 12 which spreads
and
distributes the liquid. The upper liquid-receiving layer must quickly be able
to re-
ceive a large amount of liquid within a short amount of time, i.e. have a
higher in-
stantaneous liquid absorption capability, but the lower storage and
distribution layer
12 must have a high liquid distribution capability and be able to drain liquid
out
from the receiving layer 11 and distribute this liquid in the storage and
distribution
layer 12. The differences between the layers 11, 12 can be accomplished by
density
differences. A more compressed fibre structure distributes the liquid better
than a
corresponding fibre structure having a lower density. Such a low-density
structure
has a higher instantaneous liquid absorption capability and a lower
distribution ca-
pability due to its larger pore size. Different absorption capabilities can
also be
achieved by using different fibre structures having different characteristics.
Thus
chemically produced cellulose fluff pulp shows better distribution
characteristics
compared to, for instance, mechanically or chemi-thermomechanically produced
pulp, such as chemi-thermomechanical pulp (CTMP). A fibre structure containing
chemically stiffened cellurose=fibres shows a higher instantaneous liquid
absorption
ability but a lower distribution ability compared to conventional chemical
pulp.
Other materials suitable as receiving layers 11 can be a wadding of natural
fibres or
a fluffy nonwoven material.
A partially neutralised superabsorbent is admixed in the upper liquid-
receiving layer
11 of the absorbent body 3. This superabsorbent act as a acid buffering
substance in
accordance with the present invention.
A conventional superabsorbent is admixed in the lower liquid storage and
distribu-
tion layer 12 of the absorbent body. It is advantageous to put a conventional
super-
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absorbent in the lower liquid storage layer 12, because a conventional
superabsorb-
ent has a higher total absorption capacity compared to a partially neutralised
and
pH-regulating superabsorbent.
Naturally, the invention also comprises other embodiments of the absorption
body.
The absorbent body may contain both partially neutralised superabsorbents and
conventional superabsorbents, and both the superabsorbents can be equally
distrib-
uted in both the upper and lower absorbent layers. Moreover, except for
cellulose
fluff pulp it is possible to only include one kind of superabsorbent material.
In that
case, the superabsorbent material also acts as a pH-regulating substance in
accor-
dance with the present invention.
Experimental work
A study was carried out in order to determine whether different environmental
pH
affects Candida infections on skin. Fifteen female, healthy volunteers between
30
and 63 years of age (average 44.5 years) participated. The following routine
proce-
dures and materials were used:
The experimental patches were made of common diaper materials and punched out
as circular disks with a diameter of 70 mm. The outer side of polyethylene and
the
inner side (that will be placed towards the skin) of nonwoven polypropylene
were
glued together with a 10 mm edge around the inner circular core of 50 mm
diameter.
The inner core consisted of approximately 0.85 g cellulose pulp and
approximately
0.15 g of superabsorbent polymer (IM 7100 and E 127/97, Clairant GmbH, DE).
The
superabsorbent polymer was a polyacrylic acid, which was adjusted to either pH
4.5
or 6Ø It acts as a strong buffering system. 104 cells per ml C. albicans
were sus-
pended in a physiological saline solution. 7 ml of this solution was added to
each
patch, 15 minutes before they were attached to the forearms.
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Skin surface pH was measured with a Courage+Khazaka PH900, Mettler-Toledo
flat electrode 304. Every morning and afternoon the instrument was calibrated
at pH
4.0 and 7Ø The instrument accuracy is 0.1 units. A few drops of deionized
water
was added to the electrode before measurement and the average of three values
was
recorded.
The C. albicans strain used was type H29, kindly provided by Professor Lars
Edebo, Department of Microbiology, Sahlgrenska University Hospital, Goteborg,
SE. Cells were grown on Sabouraud's glucose agar at 37°C for 24 hours
before use.
A modification of the Williamson-Kligman scrub technique was used for assess-
ment of the resident skin microflora and the added C. albicans. A stainless
steel ring
with an internal diameter of 2.6 cm and covering a skin area of 5.5 cm2 was
used.
One millimetre of sterile 0.075 M phosphate buffer (pH 7.9) containing 0.1%
Triton
X-100 was poured into the ring, and the skin was gently rubbed with a blunt
sterile
glass rod for one minute and the fluid was removed with a Pasteur pipette
(Faerge-
mann J. Mapping the Fungi of the Skin. Handbook of Non-invasive Methods and
the Skin, chapter 10.2, CRC Press, 1995). Serial dilutions were performed in
PBS
and samples from the dilutions were plated out. Plates were incubated at
37°C and
read after 48h.
The paired t test was used to test for statistical significance between pH
differences,
differences in number of Candida organisms. The differences in observed skin
1e-
sions were tested by a sign test.
At the start of the trial, skin microflora was determined with the scrub test.
All sub-
jects had coagulase-negative Staphylococci (range 170-25000 colony-forming
units
(cfu)). Two of the subjects had Diphteroid sp (range 50 -2400 cfu). Four
subjects
had Bacillus sp (range 10-1200 cfu). One subject had S. aureus on one arm (10
cfu).
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The amounts are given in colony-forming units per 5.5 cm2 skin. No growth of
C.
albicans was found in any subject before the trial.
The skin surface pH of the 15 volunteers was measured at the start and varied
be-
tween 4.5 and 6Ø The mean value was 5.2. The results are shown in figure 2.
Patches preloaded with a Candida suspension ( 104 cells/ml) were taped to the
fore-
arms of the volunteers. The patches had two different pH-values and were
randomly
placed on either left or right arm. The patches were worn under strict
occlusion for
24 hours. The patches were removed, and after approximately 2 minutes pH
values
of the skin was measured. When the patches were removed after 24 hours of
occlu-
sion the pH was 5.1 +/- 0.18 and 5.7 +/-0.29 (mean +/- SD) at the two
respective
sites. The difference is statistically significant at p<0.0001. The skin was
visually
examined and was sampled to determine the number of cfu of Candida in an area
of
5.5 cm2. The summarised results are shown in table II. No statistically
significant
difference (P=0.64) was found between the "acidic" site and the reference
site.
Growth was found on both arms in 13 subjects. In one subject growth was found
only on the "acidic" site, and in one subject only on the reference site.
After 48 hours, the pH measurements as well as the Candida sampling were re-
peated. The results of the pH~measurements are disclosed in figure 3. The
results of
the Candida samplings after 48 hours, i.e. 24 hours after the patches had been
re-
moved and the lesions had become visually evident, show that 9 subjects had no
growth at all of C. albicans. Three subjects showed low numbers (10-130 cfu)
and
one subject had an increased growth since the day before (1400 and 4300 cfu on
re-
spective arms). Two subjects were missing on this occasion, and accordingly no
mi-
crobial data could be obtained.
The skin lesions were visually assessed. No reaction = 0; faint reaction = l;
evident
reaction = 2; strong reaction = 3. The reading was blinded and the patch type
un-
known to the assessor. The skin reactions were also recorded on photographs.
This
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visual assessment of skin reactions gave a very clear result. The acidic site
had less
severe reactions than the reference site in all 14 subjects that reacted. The
sign test
shows a statistically significant difference at p<0.001 for difference in
reaction at
the two sites. The detailed result is presented in table I.
Consequently, the pH-induced differences turned out not to be due to inhibited
growth of Candida albicans. They are probably due to a pH influence of the
viru-
fence capacity of the fungus and/or an improvement of the host's defence
ability.
9
