Wound care device

Abstract

The present invention relates to a wound care device, and more specifically to an absorbent wound care device and a method for making the same. The wound care device is obtainable by bringing together a first material and an acidic substance to form an intermediate device, which first material does not substantially gel when exposed to a fluid but does gel when brought together with an acidic substance and exposed to a fluid, and exposing the intermediate device to ethylene oxide.

Claims

1. A wound care device obtainable by exposing to ethylene oxide an intermediate device, the intermediate device comprising a first material comprising chitosan, a partially de-acetylated chitin and/or a chitosan derivative in the form of fibres, particles, granules, flakes, powder, or a combination of two or more of the aforesaid, and an acidic substance absorbed in or coated on a second material without permanent bonding occurring, which first material does not gel when exposed to a wound fluid but does gel when brought together with the acidic substance and exposed to a wound fluid, wherein the first material and the acidic substance of the intermediate device do not react with each other prior to exposing the intermediate device to ethylene oxide.

2. A wound care device as claimed in claim 1, wherein the chitosan is in the form of fibres.

3. A wound care device as claimed in claim 1, wherein the acidic substance comprises one or more acids.

4. A wound care device as claimed in claim 3, wherein the one or more acids are selected from any of the following: formic, acetic, halogen acetic acids, ascorbic, hydrochloric, sulphuric, propanoic, propenoic, lactic, succinic, acrylic, glyoxylic, pyruvic or a hydroxy propionic/butanoic acid, or combinations thereof.

5. A wound care device as claimed in claim 1, wherein the second material and the acidic substance do not react with each other prior to exposing the intermediate device to ethylene oxide.

6. A wound care device as claimed in claim 1, wherein the second material is selected from any of the following: cellulose, cellulose derivatives, cotton, alginate, viscose, polypropylene, polyethylene or combinations thereof.

7. A method of using the wound care device of claim 1 by applying the wound care device to a physiological target site to absorb a discharge of a bodily fluid.

8. A wound care device as claimed in claim 1, wherein the wound fluid is a water-containing fluid selected from the group consisting of water, saline, wound exudates, blood, and combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described further by way of example with reference to the following drawings which are intended to be illustrative only and in no way limiting upon the scope of the invention:

(2) FIG. 1: is a graphical representation showing change in absorbency of a sample wound care device exposed to different sterilisation methods;

(3) FIG. 2: is a graphical representation showing post-compression fluid retention for a sample wound care device exposed to different sterilisation methods;

(4) FIG. 3: is a graphical representation showing absorbency over time for a sample wound care device in accordance with an embodiment of the present invention exposed to different sterilisation methods;

(5) FIG. 4: is a graphical representation showing absorbency over time for a further sample wound care device in accordance with an embodiment of the present invention exposed to different sterilisation methods.

DETAILED DESCRIPTION

(6) The following specific examples of the present invention compare the absorbency of four sample wound care devices following exposure to ethylene oxide in accordance with the present invention, gamma irradiation and no sterilisation.

(7) In the preparation of Samples A and B below, the lactic acid was coated onto a first material of chitosan fibres. In Samples C and D, the lactic acid was coated onto a second material of cellulose fibres, with the first material of chitosan fibres being uncoated. In Samples A to D, the acidic substance does not react with the chitosan fibres, or the cellulose fibres, before exposure to ethylene oxide, or gamma radiation.

(8) The process of coating the fibres with the acid typically comprises mixing the fibres with a solvent, typically a non-aqueous solvent, adding the acid to the mixture and then removing the solvent, typically by flashing off the solvent.

(9) Preparation of Sample A:

(10) 1.7 dtex chitosan staple fibres were carded and needled to make a non-woven fabric. Lactic acid was added to the chitosan fabric to give a concentration of 20% w/w.

(11) Preparation of Sample B:

(12) 1.7 dtex chitosan staple fibres were carded and needled to make a non-woven fabric. Lactic acid was added to the chitosan fabric to give a concentration of 55% w/w.

(13) Samples C and D were prepared in accordance with the methods described in WO2010/031995.

(14) Preparation of Sample C

(15) 2.4 dtex cellulose staple fibres (Lenzig, Austria) were manufactured. Lactic acid was added to the cellulose fibres to give a concentration of 25% w/w.

(16) The resulting fibres were blended with 1.7 dtex chitosan staple fibres in a ratio of 55:45 chitosan to cellulose (coated with lactic acid). The combined fibres were carded and needled to make a non-woven fabric.

(17) Preparation of Sample D

(18) 2.4 dtex cellulose staple fibres (Lenzig, Austria) were manufactured. Lactic acid was added to the cellulose fibres to give a concentration of 30% w/w. The resulting fibres were blended with 1.7 dtex chitosan staple fibres in a ratio of 55:45 chitosan to cellulose (coated with lactic acid). The combined fibres were carded and needled to make a non-woven fabric.

(19) The compositions of Samples C and D are shown in Table 1.

(20) TABLE-US-00001 TABLE 1 Compositions of Samples C and D No. of Cellulose Cellu- Blend ratio layers SAM- Acid lose Cellu- GSM of carded Total PLE content carrier lose:Chitosan 1 layer together gsm C 25% None 45:55 135 1 135 D 30% None 45:55 135 1 135

(21) Exposure to Ethylene Oxide

(22) Portions of non-woven fabric prepared in Samples A to D were each separately exposed to ethylene oxide in a chamber following the processing cycle (SynergyHealth-Soft Mixed Cycle) shown in Table 2 to provide inventive samples A-EtO, B-EtO, C-EtO and D-EtO according to the present invention.

(23) TABLE-US-00002 TABLE 2 Example cycle for exposure to Ethylene Oxide Pressure Step Chamber Activity Time (mins) (mbar) Temp. 1 Vacuum 20-50 68 2 Leak test 5-10 3 Nitrogen injection 10-30 400 4 Re-evacuation 15-40 68 5 Steam injection >0, 10 42 6 Steam dwell 30-50 50 7 Ethylene Oxide gas injection 5-60 366 50 8 1.sup.st post-exposure vacuum 20-60 68 9 Wash 1 - Nitrogen 20-40 876 10 2.sup.nd post-exposure vacuum 20-40 68 11 Wash 2 - Nitrogen 20-40 876 12 3.sup.rd post-exposure vacuum 20-40 68 13 Air wash x8 10-40 600 14 Post-exposure vacuum 4-11 10-40 200 15 Final air admission 15-60 1000

(24) Comparative Exposure to Gamma Irradiation

(25) Portions of non-woven fabric prepared in Samples A to D were each separately exposed to gamma irradiation (25-35 kGrays) in accordance with methods known in the art to provide comparative samples A-Gamma, B-Gamma, C-Gamma and D-Gamma.

(26) For further comparative analysis, non-sterilised portions of Samples A to D, namely, A-Non-sterile, B-Non-sterile, C-Non-sterile and D-Non-sterile, were also tested.

(27) Absorbency Testing

(28) A test solution, comprising sodium/calcium chloride containing 142 mmol/liter of sodium ions and 2.5 mmol/liter of calcium ions, was prepared to mimic serum and wound fluid.

(29) Test 1:

(30) A known area of samples A-EtO, A-Gamma, A-Non-sterile, B-EtO, B-Gamma, and B-Non-sterile was weighed (dry weight) and submerged in the test solution for 30 minutes. The end weight (wet weight) was recorded and the absorbency potential was calculated.

(31) Retention post compression was also measured. Following submergence of a sample in the test solution as described above, a weight representative of 40 mm/Mg pressure was applied to the sample for five minutes. The retention of fluid in the sample was calculated.

(32) Test 2:

(33) A known area of each of samples C-EtO, C-Gamma, C-Non-sterile, D-EtO, D-Gamma and D-Non-sterile, was weighed (dry weight), followed by submersion in the test solution over different time periods of 10 minutes, 1 hour, 24 hours, 48 hours and 5 days. The end weight (wet weight) was recorded and the absorbency potential calculated.

(34) Results

(35) The results of Test 1 are shown in Table 3 and FIGS. 1 and 2.

(36) TABLE-US-00003 TABLE 3 Absorbency and retention results for Test 1 Sample reference Sterilisation Absorbency (g/g) Retention (g/g) A Non-sterile 22.48 16.64 Gamma 22.97 13.00 EtO 30.09 23.47 B Non-sterile 24.00 17.00 Gamma 23.74 16.54 EtO 30.82 25.31

(37) Referring to FIG. 1, it is apparent that the absorbency of sample A-EtO is higher than that of samples A-Gamma and A-Non-sterile and the absorbency of sample B-EtO is higher than that of samples B-Gamma and B-Non-sterile.

(38) Referring to FIG. 2, it is apparent that the post compression fluid retention of sample A-EtO is higher than that of samples A-Gamma and A-Non-sterile and the retention of sample B-EtO is higher than that of samples B-Gamma and B-Non-sterile.

(39) The data presented demonstrates that the performance of a wound care device comprising a first material and an acidic substance is dependent on the sterilisation technique used, with samples exposed to ethylene oxide showing improved absorbency and fluid retention post-compression

(40) The results of Test 2 are shown in Table 4 and FIGS. 3 and 4.

(41) TABLE-US-00004 TABLE 4 Absorbency results for Test 2 (NT = Not tested) Absorbency (g/g)/time point Sample reference Sterilisation 10 min 1 hr 24 hr 48 hr 5 day C Gamma 18.14 17.49 17.85 17.68 17.79 EtO 21.82 20.93 26.34 29.38 21.14 Non-sterile NT 16.8 12.3 12.5 12.0 D Gamma 23.68 25.45 20.80 21.63 19.06 EtO 24.82 26.10 30.04 30.45 27.06 Non-sterile NT 27.9 24.2 22.0 22.0

(42) Referring to FIG. 3, it is apparent that the absorbency of sample C-EtO is higher than that of samples C-Gamma and C-Non-sterile.

(43) Referring to FIG. 4, it is again shown that the absorbency of sample D-EtO is higher than that of samples D-Gamma and D-Non-sterile.

(44) The data presented demonstrates that the performance of a wound care device comprising a first material and a second material having an acid associated therewith is dependent on the sterilisation technique used.

(45) The wound care device is designed to absorb fluid and create a gel to maintain a moist wound environment.

(46) The results from FIGS. 3 and 4 also show that the initial absorbency of a wound care device exposed to ethylene oxide is higher than that of the wound care device exposed to gamma irradiation, or no sterilisation at all.

(47) In the prepared samples C and D, it has also been discovered that when the lactic acid level is between 25-30% of the cellulose fibre, the wound care device exposed to ethylene oxide gels and maintains its structure over the five-day test period, having an absorbency greater than the corresponding gamma irradiated wound care device and the non-sterile wound care device.

(48) It is of course to be understood that the present invention is not intended to be restricted to the foregoing examples which are described by way of example only.