AU778633B2 - Use of a buffer to prevent candida albicans infections on the skin - Google Patents

Description

WO 01/39582 PCT/SE00/02165 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. Examples 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 connection with using skin-occlusive, mucous membrane-occlusive and absorbent articles such as diapers, pantyliners, sanitary napkins and wound dressings. Candida albicans has been found to correlate with severity of diaper dermatitis (Benjamin L, Pediatrician 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 bibliography. 2 n d ed. 1988, Bailliere Tindall). Dimorphism, the ability ofC. albicans 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., Microbiology, vol. 140 (1994), p. 281-287). Clinical observations of diabetic patients, 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 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 substantially 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 by using a partially neutralised superabsorbent or organic acid salt buffering solution. 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 or a surgical tape, said article containing a partially neutralised superabsorbent or organic acid salt buffering solution as a pharmaceutically acceptable non-toxic and non-irritating ingredient capable of buffering within the pH range 2.0 to 5.5, is used for preventing skin irritations and lesions caused by Candida albicans.

Detailed description of the invention i Accordingly, the present invention relates to using a partially neutralised superabsorbent or an organic acid salt buffering solution capable of buffering within the pH range 2.0 to 5.5, for preparing a skin-occlusive or mucous membrane-occlusive article for preventing skin irritations and lesions caused by Candida albicans. Examples of suitable buffering ingredients are superabsorbent particles showing a level of neutralisation within the range of 20 to 50%, and 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 containing 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 substance 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 derivatives, nystatin and ciclopirox olamine. These compounds are added to the skin-occlusive or mucous membrane-occlusive article in amounts corresponding to common therapeutical doses. The present invention will now be described with reference to the enclosed figures and tables, in which: co 0 0 0 *0i0 loll0 0 WO 01/39582 PCT/SE00/02165 Figure I 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 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 gurround 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 intended 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 which may consist of elastic strings, elastic threads, elastic foam or another suitable WO 01/39582 PCT/SE00/02165 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 11 and a lower layer 12 which spreads and distributes the liquid. The upper liquid-receiving layer must quickly be able to receive a large amount of liquid within a short amount of time, i.e. have a higher instantaneous 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 capability 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 cellulose-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 distribution layer 12 of the absorbent body. It is advantageous to put a conventional super- WO 01/39582 PCT/SE00/02165 absorbent in the lower liquid storage layer 12, because a conventional superabsorbent 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 distributed 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 accordance 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 and 63 years of age (average 44.5 years) participated. The following routine procedures 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) ofnonwoven 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 E127/97, Clairant GmbH, DE). The superabsorbent polymer was a polyacrylic acid, which was adjusted to either pH or 6.0. It acts as a strong buffering system. 10 4 cells per ml C. albicans were suspended in a physiological saline solution. 7 ml of this solution was added to each patch, 15 minutes before they were attached to the forearms.

WO 01/39582 PCT/SE00/02165 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 and 7.0. 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 0 C for 24 hours before use.

A modification of the Williamson-Kligman scrub technique was used for assessment 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 cm 2 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 (Faergemann 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 0 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 lesions were tested by a sign test.

At the start of the trial, skin microflora was determined with the scrub test. All subjects had coagulase-negative Staphylococci (range 170-25000 colony-forming units 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).

WO 01/39582 PCT/SE00/02165 The amounts are given in colony-forming units per 5.5 cm 2 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 between 4.5 and 6.0. 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 forearms 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 occlusion the pH was 5.1 0.18 and 5.7 (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 cm 2 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 repeated. 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 removed 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 respective arms). Two subjects were missing on this occasion, and accordingly no microbial data could be obtained.

The skin lesions were visually assessed. No reaction 0; faint reaction 1; evident reaction 2; strong reaction 3. The reading was blinded and the patch type unknown to the assessor. The skin reactions were also recorded on photographs. This WO 01/39582 PCT/SE00/02165 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 virulence capacity of the fungus and/or an improvement of the host's defence ability.

Claims (11)

1. Use of an organic acid salt buffering solution capable of buffering within the pH range 2.0 to 5.5, for preparing a skin-occlusive article or a mucous membrane-occlusive article for preventing skin irritations and lesions caused by Candida albicans.

2. Use of an organic acid salt buffering solution capable of buffering within the pH range 2.0 to 5.5, together with a pharmaceutically acceptable antifungal agent, for preparing a skin-occlusive article or a mucous membrane-occlusive article for preventing skin irritations and lesions caused by Candida albicans.

3. Use according to claim 2 wherein the antifungal agent is an imidazole derivative, nystatin or ciclopirox olamine.

4. Use according to any one of claims 1 to 3 for preparing a skin-occlusive or mucous membrane-occlusive article, which is an absorbent article. Use according to claim 4 wherein the absorbent article is a diaper, sanitary napkin or pantyliner. Use according to any one of claims 1 to 3 for preparing a skin-occlusive or mucous membrane-occlusive article which is a wound dressing, a plaster, a surgical tape, or a like article.

7. Use according to any one of claims 1 to 3 for preparing a skin-occlusive article or a mucous membrane-occlusive article, which is a glove, a prosthesis, or an indwelling catheter.

8. A method of preventing skin irritations and lesions caused by Candida albicans, the method including administering to a skin-occlusive article or a mucous membrane-occlusive article an organic acid salt buffering solution capable of buffering within the pH range 2.0 to 11

9. A method of preventing skin irritations and lesions caused by Candida albicans, the method including administering to a skin-occlusive article or a mucous membrane-occlusive article an organic acid salt buffering solution capable of buffering within the pH range 2.0 to 5.5, together with a pharmaceutically acceptable antifungal agent. The method according to claim 9 wherein the antifungal agent is an imidazole derivative, nystatin or ciclopirox olamine.

11. The method according to any one of claims 8 to 10 wherein the skin- occlusive or mucous membrane-occlusive article is an absorbent article.

12. The method according to claim 11 wherein the absorbent article is a diaper, sanitary napkin or pantyliner.

13. The method according to any one of claims 8 to 10 wherein the skin- occlusive or mucous membrane-occlusive article is a wound dressing, a plaster, a surgical tape or like article. 15 14. The method according to any one of claims 8 to 10 wherein the skin- S. occlusive or mucous membrane-occlusive article is a glove, a prosthesis, or an indwelling catheter.

15. Use of an organic acid salt buffering solution substantially as hereinbefore described with reference to the examples and accompanying figures and tables. DATED this 6th day of October 2004 SCA HYGIENE PRODUCTS AB WATERMARK PATENT TRADE MARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA KJS/JPFNRH P21365AU00