Gerit D. Mulder, DPM, MS; Joseph P. Cavorsi, MD; Daniel K. Lee, DPM


Wounds. 2007;19(7):173-182. 

In This Article

Biosynthesized Cellulose Wound Dressing— Antimicrobial (BWD-PHMB)

Biosynthesized cellulose wound dressings (XCell Cellulose Wound Dressing and XCell Cellulose Wound Dressing Antimicrobial) were developed to maintain a moist wound environment without causing maceration, reduce pain, and enable autolytic debridement. This is possible because the dressings effectively absorb exudate and hydrate dry areas of a wound different from other dressings that have only a single function.[43]

A 49-patient, multicenter, controlled, randomized clinical study was conducted to demonstrate effectiveness of BWD compared to standard of care on venous leg ulcers. Significantly more autolytic debridement, significantly reduced pain, and cleaner wound margins were demonstrated after the 12-week study period.[44,45] Improved rate of wound closure, as demonstrated by increased epithelialization and granulation tissue, was also noted.[43]

The antimicrobial version of BWD (BWD-PHMB) contains cellulose, water, and 0.3% polyhexamethylene biguanide (PHMB). BWD-PHMB is indicated for use on partial- and full-thickness wounds. It is designed to cover a wound or burn, absorb areas of wound exudate, and provide a moist wound environment that supports autolytic debridement of nonviable tissue. The dressing may be used on moderately exuding, nonexuding, and dry wounds. It also protects against abrasion, desiccation, and external contamination. The moist environment has a cooling effect that has demonstrated a significant reduction of pain.[45]

Preclinical Efficacy Testing

BWD-PHMB demonstrates it effectiveness against a variety of organisms. Following a modified American Association of Textile Chemists and Colorists (AATCC) Method 100, samples were incubated with approximately 106 CFU/mL of the various challenge organisms. After 24 hours, a second count was made to determine the reduction in the number of organisms present. Results indicated 99.9% reduction of MRSA, Escherichia coli, Enterococcus faecalis, Bacillus subtilis, and Candida albicans within the 24-hour period.

Release of PHMB from BWD-PHMB

A study was performed to demonstrate the release of PHMB from BWD-PHMB. Five sterile 3.5-in x 3.5-in samples were used. One quarter of the dressing was used to determine the initial PHMB concentration in each dressing using UV-Vis (Ultraviolet-Visible) Spectroscopy (Genesys99 10 UV, Thermo Spectronic, Rochester, NY) at a wavelength of 234 nm. The remainder of the sample was weighed and placed into 20 times its weight in filtered water. At various times, including 0.5, 1, 2, 3, 4, 5, 6, and 24 h, the solution was assayed for PHMB concentration. At the 24-h time the dressing was removed from the tray, weighed, and an extract was taken and assayed for PHMB concentration.

Figure 1 illustrates the concentration of PHMB over time. Equilibrium was reached after about 3 hours with the concentration (in ppm) in the dressing equaling the concentration in the solution. This demonstrates that the PHMB is not bound to the cellulose and therefore can be released into surrounding fluid along a concentration gradient.

Figure 1.

Release of PHMB into solution.

Clinical Case Series

BWD-PHMB was evaluated in an open enrollment, noncontrolled clinical trial. Standard procedures for wound care were followed and samples of wound fluid were tested for type and level of microbial colonization at initial administration and 1-7 days after BWD-PHMB placement.


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