Hydrocolloid adhesive mass useful for medical purposes

Details Hydrocolloid adhesive mass useful for medical purposes Hydrocolloid adhesive mass useful for medical purposes

2000-09-05

2002-04-23

Kishore, Gollamudi S. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Web, sheet or filament bases; compositions of bandages; or...

C424S445000, C424S448000, C424S078060

Reexamination Certificate

active

06375977

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to novel hydrocolloid adhesive masses with increased absorption in the first few hours of use.
The invention further relates to the use of these novel hydrocolloid adhesive masses for medical purposes in dermatology or cosmetology, particularly for the production of dressings for the treatment of blisters, exudative wounds, burns and superficial, deep, chronic or acute dermo-epidermal lesions.
The treatment of superficial, deep, chronic or acute dermo-epidermal lesions, burns and, in particular, exudative wounds is a complex problem to which the dressings developed: in recent years have not provided totally satisfactory solutions.
The loss of substances caused by a mechanical compression which creates tissue ischemia, or by problems of vascular origin (irrigation, pressure, etc.), an injury (ablation of tissue,: flesh, etc.), an abscess or a burn, is generally referred to as the exudation of a wound. The phenomenon of exudation corresponds to excretion of the biological fluids produced by the wound throughout the healing process.
Exudation originates from the blood and is controlled by the mediators of the inflammatory reaction (vasodilation and vasoconstriction) with passage of these fluids through the vascular membranes. These fluids then flood the bed of the wound and constitute the factors which favor degradation of the perilesional healthy tissues, accompanied in particular by maceration phenomena and risks of superinfection.
The role of a dressing is to absorb these fluids while at the same time maintaining in contact with the wound a moist environment which favors the healing processes.
The ideal dressing must therefore be capable of absorbing these exudates throughout the healing of the wound.
Depending on the severity of the wound, this. healing process may extend from a few days, for wounds producing very little exudation, to several months. This involves changing the dressing frequently in order to maintain its absorption capacity and its efficacy.
To minimize the number of changes of dressing, which are traumatizing for the patient and for the healing quality (pulling-away of neoformed tissues, bleeding, pain, etc.), so-called “hydrocolloid” dressings based on hydrocolloid adhesive masses are now used to maintain an absorption capacity over 2 to 4 days.
These hydrocolloid adhesive masses, also described as hydrophilic adhesive masses, are formed mainly of an adhesive matrix, generally consisting of at least one elastomer selected from polymers such as polyisobutylenes or poly(styrene/olefin/styrene) block copolymers, which may or may not be associated with adhesion improvers such as sticky resins, or tackifying resins, plasticizers such as polybutenes or plasticizing oils, or cohesion improvers such as butyl rubbers, etc., and of one or more hydrocolloids.
Numerous hydrocolloid adhesive masses employed in the production of such dressings have already been described. Examples which may thus be mentioned are patent US:3 972 328 and the following patent applications: FR-A-2 495 473, EP-A-130 061 and EP-A-302 536.
However, none of these documents tackles another important aspect of exudation, namely its kinetic aspect over time.
It is in fact known that the phenomenon of exudation is always more important at the start of the healing process, which corresponds to the critical phase of the inflammatory reaction. This inflammatory reaction is most important during the first 4 hours, so it is a matter of urgency to re-establish the hemostatic equilibrium of the wound, i.e. to increase the absorption capacity during the first few hours. In fact, the more rapidly this equilibrium is reached, the less the wound will weep and the better the absorption capacity of the dressing will be maintained at a high level over several days. It will thus be possible to make the changes of dressing less frequent and avoid the associated disadvantages already mentioned.
Likewise, each time the dressing is changed when the wound is tended, cleaned and disinfected, and before a new dressing is applied, the wound is faced with a more aggressive environment (contact with the air, loss of moisture, etc.). This causes a resumption of the inflammatory reaction, which will induce an increase in the exudates produced, so there is again a need in this case to increase the absorption capacity during the first few hours.
An ideal dressing should therefore be adapted to the amount of exudates produced, but also to theirate of production.
To adapt the absorption capacity to the rate of production, one might consider increasing the amount of hydrocolloid which gives these adhesive masses their absorption property. However, if too much of this type of product is incorporated into the adhesive mass, said products will swell proportionately to their concentration and will degrade the physical properties of the dressing, resulting in a loss of cohesion and meaning that the dressing falls apart when removed or may even be wasted. Consequently, this solution cannot be satisfactory because this situation once again raises the problems associated with changing of the dressing and with the life of the dressing.
OBJECTS OF THE INVENTION
Under these conditions, the object of the present invention is to solve the new technical problem consisting in the provision of a hydrocolloid adhesive mass of novel composition which has a high absorption as from the first few hours without impairment of its properties of cohesion, adhesion and manageability in the medium and long term.
SUBJECTS OF THE INVENTION
It has been discovered that it is possible to solve this technical problem in an entirely satisfactory manner, which is simple to implement, by incorporating an ethoxylated sorbitan fatty acid ester, preferably a monoester, into a traditional hydrocolloid adhesive mass. It is this discovery which constitutes the basis of the present invention.
Furthermore, it has been found that the addition of an ethoxylated sorbitan fatty acid ester to a traditional hydrocolloid adhesive mass, particularly an adhesive mass comprising an elastomer of the poly(styrene/isoprene/styrene) type, affords a significant increase in the capacity of said mass to discharge the absorbed fluids by increasing the permeability to water vapor. Thus the novel hydrocolloid masses according to the invention can be used to produce dressings which are capable of eliminating the absorbed fluids and, consequently, of maintaining an absorption-elimination equilibrium and a moist environment favorable to healing.
Thus, according to a first feature, the present invention relates in general terms to a hydrocolloid adhesive mass consisting of a hydrocolloid and an adhesive matrix, with which an acrylate polymer with a glass transition temperature below −20° C. may or may not be associated, and of an ethoxylated fatty acid ester.
More precisely, the present invention relates to a hydrocolloid adhesive mass useful especially for medical purposes, characterized in that said hydrocolloid adhesive mass comprises:
(a) 0.2 to 5 parts by weight of an ethoxylated sorbitan fatty acid ester;
(b) 20 to 50 parts by weight of a hydrocolloid;
(c) 32 to 120 parts by weight of an adhesive matrix made up of one or more polymers selected from poly(styrene/olefin/styrene) block copolymers, low-molecular polyisobutylenes and high-molecular polyisobutylenes, and one or more compounds selected from sticky resins, or tackifying resins, plasticizers, polybutenes, antioxidants, ethylene/vinyl acetate copolymers, butyl rubbers and ethylene/propylene block copolymers; and
(d) 0 to 15 parts by weight of an acrylate polymer with a glass transition temperature below −20° C.
Ethoxylated sorbitan fatty acid ester is understood here as denoting ethoxylated sorbitan fatty acid esters (especially monoesters, triesters or mixtures thereof) in which each fatty acid part of the ester contains from 8 to 22 carbon atoms and is a linear or branched chain, preferably a linear chain, which is saturated or possesses one or more sites of olefinic

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