CA2037726A1

CA2037726A1 - Wound dressing of hydrophobic macroporous cloth and oligopeptides

Info

Publication number: CA2037726A1
Application number: CA 2037726
Authority: CA
Inventors: Burton W. Blais; Hiroshi Yamazaki
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-03-07
Filing date: 1991-03-07
Publication date: 1992-09-08

Abstract

ABSTRACT OF THE DISCLOSURE
A novel wound dressing is provided herein. It comprises a hydrophobic macroporous cloth having an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B
hydrophobically and stably bound thereon and therein. Such dressing is ideal for removing LPS endotoxins.

Description

This invention relates to a wound dressiny cloth.
In man and other animals, many Gram negative bacterial pathogens infecting wounds and open abrasions on the skin release lipopolysaccharide (LPS) endotoxins which may cause inflammation, septic toxaemia and other complications which seriously compromise the infected individual.
Many bacterial lipopolysaccharides cause fever in animals or humans; hence, they are often termed "pyrogens". As they are produced within the bacterial cell, they are also called "endotoxins". Lipopolysaccharides are major antigens on the cell surface of gram-negative bacteria.
Polymyxin B is an antibiotic which is bactericidal to gram-negative bacteria. Polymyxin B is a cyclic peptide with a short peptide side chain acylated at its N-terminus with an eight or nine carbon fatty acid. It is known that polymyxin B, when covalently immobilized onto agarose beads, can bind to lipopolysaccharide pyrogens (see Issekutz, in the Journal of Immunological Methods (1983) 61: 275-281). This author described the use of polymyxin B covalently immobiliæed onto agarose beads, to remove lipopolysaccharide pyrogens in solution. This was done in a bead-packed column. Such beads are expensive and hard to handle; they must be contained and must be chemically activated in order to allow the immobilization of the~ polymyxin. Polymyxin is stable between pH 2 and 7, even when boiled. Polymyxin can react with lipopolysaccharide antigens of all gram-negative bacteria, including Salmonella spp, Escherichia coli, BrucelIa abortus and Campylobacter spp.
As taught in applicant's copending application Serial No.

2,017,093 filed May 17, 1990, polymyxin B will, bind directly to any hydrophobic surface, e.g. a macroporous polyester cloth which may be woven or unwoven, or may even be matted fibres, by simple adsorption. Polymyxin B can adsorb hydrophobically to such hydrophobic surface 8.g., polyester, via its fatty acid residues.
As taught in that pending patent application, polymyxin B will `

~7~26 adsorb to woven and non-woven cloth, and matted fibre made of hydrophobic materials. Polymyxin B adsorbs best to polyester, but less satisfactorily with polypropylene cloth, polyaramide cloth, or nylon cloth.
This direct binding of polymyxin B to hydrophobic substrates, e.g. SONTARA 8100 is to be contrasted to the ionic binding taught in copending application Serial No. 564,950 filed April 22, 1988.
In that application, a substrate, at least a part of which is cellulosic, is reacted with selected reagents to provide ionic binding sites thereon, and then in ionic form of a drug, ~hich may be polymyxin B is bound to the cloth ionically. The ionic form of the drug can then be eluted from the ionic binding sites in the cloth by ion exchange with ions in body fluids (in the wound). In this way, the drug exerts its beneficial effect.
The present invention does not reside in such ionic binding/ion exchange phenomenon. Instead, the present invention proposes to take advantage of the known properties of polymyxin B
to provide a wound dressing which can absorb LPS fr~m wounds.
Thus, by the present invention, a wound dressing is provided comprising a hydrophobic macroporous cloth having an oligopeptide, a hydrophobic polypeptide, or a polymyxin hydrophobically and stably bound thereon and therein. Preferably, the wound dressing comprises a hydrophobic macroporous cloth having polymyxin B which is hydrophobically and stably bound to a hydrophobic macroporous cloth and does not elute out therefrom. This makes such dressing ideal for removing LPS endotoxins.
Polymyxin is an antibody complex produced by Bacillus polymyxa: .
~ ~ 2 L-DAB - D-X J L-Y
=
R~ L-DAB ~ L-Thr > Z ~ L-VAB
= I = ~. ~
~H2 L-Thr L-DAB- L-D B

'Y -N~2 'Y -NH2 :. . - , . :

DAB ~ diaminobutyric acid 21~3~72~

Polymyxin B. M1xture of polymyxins B1 and B2.
Polymyxin B1. C56H98N16013- R = (+)-6-methyloctano-yl; X
phenylalanine; Y = leucine; Z = L-DAB.
Polymyxin B2- c5sH96N16o13~ R = 6-methylheptanoyl; X = phenylalanine;
Y = leucine; Z = L-DAB.
Polymyxin Dl. CsoH93N15O15. R = (+)-6-methyloctano-yl; X = leucine;
Y = threonine; Z = D-serine.
Polymyxin D2. C49H91N15015. R = 6-methylheptanoyl; X = leucine; Y =
threonone; Z = D-serine.
Colistin.

L-018--D-Leu ~ L-L~J
/= = =
R ; L-DA3 ~ I.-Thr--~ I.-DAa ~ L-DAB
= I = = I = ~
H2 `~-~2 L-Thr--L-D.~8 L-DA~
~r ~H2 ~r ~H2 DAB = ~,~-diamirlobu~yri~acid colistin A- Cs3H100N1613~ poly y 1 R = (+)-6-methyloctanoyl.
Polymyxin E C52H98N16Ol3. R = 6-methylheptanoyl.
The term "macroporous" as applied to cloths when used herein is intended to mean textiles composed of hydrophobic synthetic polymeric fibers, which are either woven or non-woven into a physically structurally stable cloth of more than about 200 ~m thickness, such that the pores (i.e., spaces between the fibers) exceed about 20 ~m in diameter.

203772~

Macroporous cloths may be made substantially completely from synthetic fibres selected from the group consisting of polypropylene, polyethylene, nylon, and polyester. Such macroporous cloth have the following characteristics: they can accommodate a larger volume of an oligopeptide, e.g. a hydrophobic polypeptide or a pol~myxin, preferably polymyxin B per area; they have a larger surface area for binding to an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B;
they have minimum flow resistance; and they have both strength and durability. Such macroporous cloths, by virtue of their hydrophobic characteristics, have been found to adsorb and absorb an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B since they provide a large surfac~ area for an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B capture. Macroporous cloths all have such minimum flow resistance.
Such macroporous hydrophobic cloths made of, e.g.
polypropylene and polyester, are readily commercially available and are moderately priced because of their large commercial demand as textiles and filters. Macroporous 100% nylon cloth is commercially available as a generic product and may he acquired locally in the Ottawa, Canada area. Macroporous woven polyester cloth is commercially available as a generic product and may be acquired locally in the Ottawa, Canada area~ Macroporous, non-woven polypropylene filter cloth is available as a generic product and may be purchased from Aldrich Chemical Co. A variety of non-woven, macroporous, polyester cloths may be obtained from DuPont, and is known by the trade-mark SONTARA.
one preferred embodiment of such SONTARA is SONTARA 81O0TM, which has the following chemical and physical characteristics.
Typical Physical Properties of SONTARA 8100 are:
(in English Units) UNI~- ~Hlc~ leSSSH'ET G;lA5TRAPE--013 . MUCL5N FRAZI'R AIR ROLL SIZE
WEIGHT TENSILE ZEAR 5URSIPERMeAElU~ (~" ID ~ )RE~
(c:lyc.~ (milsl ~Ibs) (1~ F~il (CFM~ in. Iln. , MU X~ IdD XD @ a5 ~ H~O) O.D. yc S~yle 100/. ?olyester 2 ~ t~ ~ ~

Frazier Air Permeability is described in ASTM D737-75, and is attached hereto as Appendix I.
The term "hydrophobic~ as applied to cloths when used herein is intended to mean that the cloths repel water, the degree o~
repelling being dependent on the pore size and the inherent polymeric properties.
The term "non-woven" when referring to the cloth is intended to mean a cloth formed ~rom a random arrangement of natural or synthetic fibres by adhesives, heat and pressure, or needling techniques.
It has thus been found that, since polyester cloth coated with an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B has a proven capacity for binding bacterial LPS, a dressing consisting of a sheet of polyester cloth coated with an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B can be applied to open wounds in order to absorb the serous fluids and adsorb the LPS contained therein. This removes the endotoxin from local circulation and improves the prognosis for a more rapid and complete recovery from infection.
The efficiency of removal of LPS endotoxins by the hydrophobic macroporous cloth coated with an oligopeptide, e.g. a hydrophobic polypeptide or a polym~xin, preferably polymyxin B may be enhanced by simultaneously applying to the wound site any suitable non-toxic detergent, which will complex with LPS in such a manner as to increase the affinity of the latter for the oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B
adherèd to the cloth. Thus, the present invention also provides a wound dressing comprising a hydrophobic macroporous cloth to which an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B is hydrophobically and stably bound, and to which a synergistically-e~fective amount of a suitable, non-toxic detergent is also absorbed. Suitable such non-toxic detergents include sodium deoxycholate, sodium dimethyl 2 ~ 7 ~ ~

sulfonate, polyoxyethylene derivatives of fa-tty acid partial esters of sorbitol anhydrides, alkylaryl polyether alcohols, alkylaryl polyether sulfonates, and alkylaryl polyether sulfates.
By yet another aspect of this invention, the macroporous, hydrophobic, e.g. polyester, cloth coated with an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B is made sterlle by autoclaving at 121C for 10 - 20 min. (which treatment does not affect the ability of such cloth coated with an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B to bind LPS), thereby to increase the sanitary effect of the dressing.
By a still further aspect of this invention it has been found that the macroporous hydrophobic cloth coated with an oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B may act as a local bactericidal agent (at the site o-f application) by virtue of the antibiotic properties of the adhered oligopeptide, e.g. a hydrophobic polypeptide or a polymyxin, preferably polymyxin B.
EXAMPLES
The following examples teach the preparation of the polymyxin B-coated cloths.

Polymyxin B may be coated onto a cloth in the following manner.
Non-woven polyester cloth, e.g. SONTARA 81O0TM was cut into 6 mm square segments and coated with polymyxin B. The cloth was first wetted with phosphate buffered saline (PBS) and blotted.
Each cloth segment was incubated with 50 ~l of a 5 mg/ml solution of polymyxin B sulphate in PBS for 6 to 16 hours and then was washed 5 times with phosphate buffered saline with Tween 2OTH(PBST)- The washing was done at room temperature, on a macroporous filter under suction. (TWEEN is the registered trade-mark of Atlas Chemical Industries for each member of a series of ~ ~ ~ 7 ~ ~ ~

general purpose emulsifiers and surface active agents. They are polyoxyethylene derivatives of fatty acid partial esters of sorbitol anhydrides).

Polyester cloth is cut into 4 cm square sheets and each sheet was coated with 2 ml of a 5 mg/ml solution of polymyxin B sulfate in PBS, and then washed with 30 ml of PBST.
E~AMPLE 3 Polyester cloth (DuPont, SONTARA 8100) was cut into 4 x 6 cm sheets, then saturated with 3 ml of polymyxin B sulfate (5 mg/ml in PBS) and incubated for 16 hours at room temperature. Each sheet was then washed with a total of about 6 x 10 ml of PBST on a filter under suction.
The following examples describe the utility of the present invention.
EXAMPLE A
Polymyxin B-coated polyester cloth (prepared as described above) can be applied to dress wounds in instances where there exists a danger of a patient acquiring infections to the wound site by environmental contact with Gram negative bacterial pathogens.
EXAMPLE A(aj For example, burn wound victims frequently run the risk of infection by ~seudomonas aerug nesa. It is believed that such patients would benefit from a dressing composed of polymyxin B-cloth.
EXAMPLE A~b) People suffering so-called "street wounds" are susceptible to infection by enteric bacteria, e.g. KlebsieIla and Enterobacter or by members of the genus Bacteroides. It is believed that such people would benefit from a dressing composed of polymyxin B-cloth.
In each of these cases, the application to the wound of a polymyxin B-coated polyester cloth would be of value in alleviating some of the consequences of infection (i.e. absorption of pyrogens or endotoxins), or even in preventing infection by virtue of the bactericidal properties of the adhered polymyxin.
EXAMPLE B
It has been found that the efficiency of removal of LPS
endotoxins by the polymyxin B-cloth of this invention i5 enhanced by the simultaneous application to the wound site of any suitable non~toxic detergent which will react with LPS in such a manner as t~ incr~ase the affinity of the LPS for the polymyxin B adhered to the cloth. Examples of suitable such non-toxic det~rgents include sodium deoxycholate, SDS, (sodium dimethyl sulfonate) TWEEN 80, and various members of the TRITON X series (X-15, X-45, X-100, X-165 and X-705). TRITON X is the trade-mark of Rohm ~ Haas Co. for surfactants based on alkylaryl polyether alcohols, sulfonates and sulfates. They may be non-ionic, cationic or anionic, and may be either oil-soluble or water-soluble.

Claims

1. A wound dressing comprising a hydrophobic macroporous cloth having an oligopeptide, a hydrophobic polypeptide or a polymyxin hydrophobically and stably bound thereon and therein.

2. A wound dressing comprising a hydrophobic macroporous cloth having polymyxin B hydrophobically and stably bound thereon and therein.

3. The wound dressing of claim 2 wherein said hydrophobic macroporous cloth is formed of a synthetic fibre selected from the group consisting of polyester, polypropylene, polyaramide and nylon.

4. The wound dressing of claim 2 including a non-toxic detergent also absorbed into said cloth.

5. The wound dressing of claim 4 wherein said non-toxic detergent is selected from the group consisting of sodium deoxycholate, sodium dimethyl sulfonate, polyoxyethylene derivatives of fatty acid partial esters of sorbital anhydrides, alkylaryl polyether alcohols, alkylaryl polyether sulfonates, and alkylaryl polyether sulfates.

6. The wound dressing of claim 4 wherein said hydrophobic macroporous cloth is at least partly formed of a synthetic fibre selected from the group consisting of polyester, polypropylene, polyaramide and nylon and also wherein said non-toxic detergent is selected from the group consisting of sodium deoxycholate, sodium dimethyl sulfonate, polyoxyethylene derivatives of fatty acid partial esters of sorbital anhydrides, alkylaryl polyether alcohols, alkylaryl polyether sulfonates, and alkylaryl polyether sulfates.

7. The wound dressing of claims 1 or 2 which has been made sterile by autoclaving at 121°C for 10 - 20 minutes.