Note: Descriptions are shown in the official language in which they were submitted.
1 1565S5
This invention relates to-a novel preparatio~ for
the treatment of wounds, sores, ulcerations of the skin and
any other skin affection which, like the ones just named, pro-
duces discharge fluids (exudates).
In particular, the present invention provides a pre-
paration consisting essentially of microfibres of a synthetic
polymer having a surface area of more than about 30 m ~g, a
diameter of about 2 to about 10 microns and a lenyth of about
1 to 5 mm, and a carrier therefor suitable for topical treatment
of wounds, sores, ulcerations and other exudayive skin affec-
tions.
In accordance with the present invention the polymer
may be selected from the group of polymers consisting of poly-
ethylene, polypropylene, polystyrene and olefinic copolymers.
As indicated above, the novel preparation comprises
micro-fibrous materials, which are obtained from synthetic
polymers and have quite particular shapes. They are adapted to
the absorption of the exudates from the surfaces treated there-
with and to the constant maintenance of healthy, oxygen-rich
and balanced constant humidity environment such as to encourage
the occurrence and the persistence of the consitions which are
most appropriate for reinstating the physiological skin functions.
In addition, the subject preparation does not permit
that a crust may be formed directly on the skin surface which
has been damaged, but, rather, at a certain distance from the
skin: this circumstance prevents the formation of a barrier-
layer susceptible of barring the exit, from the wound, of dust,
bacteria, toxic degradation products or inflammatory agents,
and so forth. Thus, the wound can be much more conveniently
cleaned and its healing is thereby accelerated.
~ 1 -- .
C
1156~55
The microfibrous materials mentioned above have
very reduced dimensions : the diameter is from 2 to 10
micron and the length varies from 1 to 5 millimetres
~mm): in addition they have a very wide specific sur-
face area, the latter being over 30 square metres ~m2)per gram (g).
Such materials can be obtained by flash extru-
sion, that is by extrusion through a no~zle from a pres-
surized environment to an environment in which ambient
pressure obtains, the pressure differential between the
two environments being at least 30 atm. of solutions of
polymers, or, better to speak, of homogeneous solutions
of mixtures of polymers in appropriate proportions,
such as, for example, has been disclosed in the Italian
Patent Specification N 995 549 by the same Applicants.
In flashing a sudden evaporation occurs of the
solvent, with the attendant formation of microfibers
having a very tiny size.
In order that the healing of wounds, sores and
ulcerations, especially of the purulent kind, may be
achieved, it is essential to remove therefrom the exuda-
tes that they discharge, as well as the pollutants which
may induce infections, while concurrently maintaining
a correct balance of humidity sc as to ensure a clean
environment and such conditions as to encourage the ra-
pid regencration of the skin cel~s.
Above all, it is vital, in suchcases, to prevent
the formations of crusts due to the reticulation of ~ibrin,
115~5
- which adhere too closely to the wound surface and impede
a regular exchange of moisture oetween the skin and the
atmosphere, thus causing the stagnation of the exudates
and the attendant formation of infectious pockets.
There is no concordance of opinions as to the
possibility of accelerating the regeneration of skin tis-
sues in the case of wounds, ulcerations and the like.
It is certain, however, that in the case of puru-
lent or exudative affections, the removal of infected
materials or of the possible infectious medium or agent
capable of encouraging the formation of thick crusts
encourages the regeneration of the cells and thus the
healing of the inJured surface.
It has been suggested to treat wounds of exuda-
tive affections of the skin with powders or dry powdered
materials in minute particles, both of an inorganic or
organic nature, possibly also based on polymers, but
with little or no success at all.
It has also been suggested, this time with a
certain success, to use macromolecular substances con-
taining hydrophilic groups, in the form of a powder
consisting of minute, virtually spherical, particles
which absorb, presumably in a selective way, the fluids
discharged from wounds or other skin alterations, as
disclosed in the British Patent Specification 1 454 055.
It has now been ascertained, and this is the sub-
~ect matter of the present invcntion, that the local
application in the form of a dusting powder, occlusive
11~6555
pads, ointments, creams or other preparations based on
microfibres of the kind referred to above has surpri-
singly been conducive, both in the form of microfibres
above and in combination with other medicaments, to
a quick healing of the hurt skin surfaces.
In addition to absorbing and removing the noxious
fluids, these microfibres seem to ensure a fully satis-
factory transpiration of the underlying skin surface:
furthermore, the microfibres do not pack on the wounds
and do not form any hard or sticking crusts, so that they
can conveniently be withdrawn during progress of medica-
tions without causing any additional damages to thc wounds,
contrary to what occurs with the conventional wound
dressing materials.
In order that the present invention may be better
understood,a description will be given hereinafter of
test runs carried out on rabbits on which purulent sores
had been artificially induced, with a view to ascertain-
ing the effect of the microfibres on wound healing, in com-
parison with other commercial products intended for the
same purposes
Concurrently, tests have been conducted in compa-
rison with rabbits having sores of the same kind refer-
red to above, but without any application of skin wound
healing products.
DESC~IPTION OF THE TESTS
Tests have been conducted on 18 white New Zealand
rabbits. On all rabbits a sore of certain dimensions
I 156555
has artificially been induced. To this purpose, a skin
strip of 8 by 8 centimetres has been removed surgically
fr-om the back, with.anaesthesia. The exposed area was
infected by spreading thereon an admixture of mouse
and rabbit excrements, human pus and physiological solu-
tion, the whole carefully homogeneized in a mortar,
whereafter the wound so infected was covered with the
overturned skin strip and with a moistened gauze.
After having maintained the thus treated skin
portion in a moist and warm environement for four days,
the wounds were infected by a mixed bacterial flora,
mainly composed by Escherichia Coli, Proteus sp., Pseu-
domonas Aeru~inosa, Staphylococcus Aureus and Beta-
, . .
haemolytic Streptococcus.
.
Foreachrabbit the size and the exact countour
of the wound was recorded on a X-ray plate, as follows:
after the four days as from the surgical removal and
the application of infectous materials, the cover of
skin and gauze was removed from all rabbits. All the
loose dirt, crusts and pus were removed and the wounds
were irrigated with 20 mls of physiological solution. An
unexposed X-ray plàte was laid on the wound and the wound
contour was exactly traced with a pen. An arrow was pla-
ced in the direction of the head and the plate marked with
the rabbit's name, so as to be able to place subsequent-
ly the plate in the same position for each rabbit : thus
the si~e of the wound was periodica~.ly.checked and the
dateline inscri~ed.
11~6~5
6.
The marked plates, completed with all the records,
served for the determination of the wound healing time.
The wounds were checked for a total time of about
23 days : as a matter of fact, this time is the period
in which the maximum wound healing takes place, as had
been ascertained on pilot tests on two control rabbits,
even though the complete healing is experienced to re-
quire 4-~ weeks.
The eighteen rabbits, the wounds of which had
been cleaned as specified above, were divided into three
groups of 8 rabbits each.
A first group (Group 1) was the control group.
The six control animals were left with their wounds expos-
ed to air, without any medication at all. No wound dress-
ings were applied in any case since this would promote,especially in rabbits, a too intensive purulence, even in
aseptical conditions. The other two groups of six rab-
bits each received a medication, as follows : the Group
2 was medicated with a macromolecular substance obtained
by cross-linking of dextran or carboxymethyldextran with
epichlorohydrin in the form of microspherical particles,
the use of which for the dressing of exudative wounds is
disclosed in the British Patent Specification 1 454 055
and which is marketed under the Trade Mark Debrisan. The
Group 3 was treated with high-density polyethylene micro-
fibres, as obtained according to the method of the Italian
Patent Specification N 995 549 and having, as an average,
a diameter of from 5 to 10 microns, a length of from 1.4
5~5
7,
to 1.6 mm, and a specific surface area of about 40 m2lg.
The medication consisted in laying on the wounds
a layer of material: every third day the wounds were
checked and the debris removed and the applied mate-
rial withdrawn . the wound contour was traced on the
respective plates.
Each rabbit then received the medication treat-
ment exactly as before.
In order to be enabled to give a numerical evalua-
tion of the wound healing, the following method has been
adopted.
On completion of the test period, each plate car-
ried drawn thereon a set of approximately circular, con-
centrical curves.
- 15 On each plate, à cross wasdrawn in such a position
that the intersection of the CrQss-arms fell approximate-
ly upon the centre of the circumferences. The ends of
the cross-arms were oriented in the positions of 3 o'clock,
6 o'clock, 9 o'clock and 12 o'clock.
As the baseline the initial tracing of the wound
at the time of surgical skin removal was taken. Also
the last reading, that is the one corresponding to the
healing of the wound, was recorded.
The distance in millimetres (mm) between the base-
line and the ultimate tracing was measured along each
cross-arm (in the order 3, 6, 9, 12). The sum of these
distances, divided by four , gave the average length of
healed wound for each rabbit. The wound healing velocity
11~8555
was calculated by dividing the averaye length of healed
wound by the number of days requlred in total for the
healing of the wounds.
- TABLE 1 records the values relative to the heal-
ing of wounds of each animal of each group.
Subsequently, the average of the healing of
wounds was calculated for each group of rabbits, while
concurrently evaluating the average testing time for each
group by summing the healing velocity of the rabbits of
each group and dividing this sum by 6.
One of the rabbits which had been treated with
Debrisan (Trade Mark) has given an anomalous-response
-~ to the treatment because, at the end of the period of
time by which all the other rabbits had their wounds hea-
led, exhibits a pus pocket and itc wound did not heal.
The values of this second evaluation are tabulated
in TABLE 2.
It is apparent from the mere reading of the TABLES
that the rabbits of Group 3 has exhibited an improved
total (i.e. group) and average wound-healing velocity
(see particularly TABLE 2).
Moreover, the following observations have been made
on the behaviour of the wounds treated in different ways
in thc three groups of rabbits.
For the Group 1 the formation of a thick crust,
rather difficult to clean, has been noted. A portion of
the crust was so sticking that it cannot be removed with-
out damaying the wound and causing pains to the animal.
555
9.
The same problems have been experienced for the
rabbits of the Group 2: in this case, furthermore, a
few difficulties were experienced in trying to have the
Debrisan staying on the woùnd, on account of the exceed-
ingly high free-flowing property of the product, so that
the wound was left partially exposed.
For Group 3 the formation of a thick~ but light
crust was experienced, but the crust was not pasty on the
wound surface-and could easily be peeled off so that it
was easy to clean the wound quickly.
In addition, the application of the microfibrous
materials to the wounds did actuàlly proved convenient
since, due to its soft texture, it stayed easily on the
spot but without pasting.
TABLE
~ 1~6555
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11~6~5
TABLE 2
GROUP_ 1
Total Group Healing velocity 6.935 mm/day (6 animals)
Average Healing velocity 1.155 mmlday/animal
Average number of days 23~ 35
GROUP _2
Total Group Healing velocity 6,140 mm/day (6 animals)
Average Healing velocity 1.023 mm/day/animal
Average number of days 23, 33
GROUP 3
Total Group Healing velocity 8.435 mm/day (6 animals)
Average Healing velocity 1.405 mm/day/animal
Average number of days 23, 00
