Use of a New Quantitative Method to Evaluate the Action of Enzymatic, Wound Debriding Agents In Vitro

By: David Hobson, Ph. D
Eric White, B.S.
Larry Anderson, B.S.

DPT Laboratories
San Antonio, TX 78215

ABSTRACT

Enzymatic debriding agents intended for general use must work in a variety of wound bed conditions that include differences in fluid type and content, microbial flora and load, cleansers used, antimicrobial and other pharmaceutical treatments applied, pH, temperature, necrotic tissue types and amounts, etc. Any one or combinations of these factors may adversely impact the efficacy of an enzymatic debriding agent. This presentation describes the use of a new, quantitative, in vitro method to evaluate the action of enzymatic debriding agents under different wound bed conditions and the quantitative effects of different cleansing agents on the debridement efficacy of some commercially available debriding agents. This procedure produces information useful for quantitatively evaluating enzymatic debriding agent efficacy as well for identifying agents such as topical antimicrobials and wound cleansers, that inhibit or enhance the efficacy of these agents. The method can be used with a particular treatment regimen and for research toward development of new debriding agents and/or wound care products intended for use in conjunction with enzymatic debriding agents.

INTRODUCTION

Wounds that are candidates for enzymatic debridement include a multitude of etiologies and wound types. This results in the need for the wound care practitioner to identify and use enzymatic debriding preparations that work effectively in various wound bed conditions (exudate types and content, microbial load, pH, temperature, tissue hydration levels, necrotic tissue types and amounts, cleansing agents used, wound dressings, antibiotics, etc.)

As an aid to evaluating quantitatively the effects of different wound bed variables on the action of different enzymatic debriding preparations, a new, in vitro procedure has been developed.

This procedure is unique in that it is based on the application of enzymatic debridement preparations to actual tissue samples exactly as would be done in a clinical setting and then uses a glass. Franz-type diffusion cell to obtain samples suitable for quantitation of the rate and extent of debridement.

This study was conducted to assess the potential for this new procedure to be of practical value to wound care practitioners and product developers in better understanding wound bed variables that may impact on the successful use of enzymatic debriding agents. Variables examined in this study included the:

1. rate of action of different enzymatic debriding preparations.
2.effect of different types of wound cleansers used prior to debridement.

DISCUSSION

Using the denatured porcine skin model, a significant, quantifiable difference appears to exist in the rate of debridement between the three different commercial enzymatic debridement preparations tested. This could be due to differences in the types and amounts of enzyme activity in the different products, the ability of the product base to release the enzymatic agent into the skin surface, or a combination of both factors.

The observation that cleansing with 3.5% hydrogen peroxide produces a significant decrease in percent debridement with Accuzyme (tm) was not particularly surprising because hydrogen peroxide solutions are commonly known to denature enzymes. Apparently enough hydrogen peroxide still remains in the skin epidermis after 15 min. of drying to significantly reduce the rate of enzymatic activity. More surprising was the differential effects of the two different, non-ionic surfactant-based cleansers, which showed dramatic differences in their effects on the rate of enzymatic debridement relative to the saline control. Although this differential effect is clearly due to formulation factors, the exact reason for this difference remains unknown. Product labeling does indicate a difference in the chemical structures of the non-ionic surfactants used in these products which may be of significance to the observed difference in their effects on the rate of enzymatic debridement.

CONCLUSIONS

  • The in vitro model is a useful procedure to quantitatively evaluate the effect of different factors of enzymatic debridement efficacy.
  • Different commercial debriding agent preparations show quantitatively very different rates of enzymatic debridement on denatured porcine skin tissue.
  • Different wound cleansing agent/enzymatic debridement product combinations may produce widely different rates of enzymatic debridement. Prior knowledge of these effects may serve to guide significant improvements in enzymatic debridement outcomes in some settings.
  • The results from this study indicate clearly that the effective use of enzymatic debridement preparations should be viewed in the context of a while wound care approach that would include the types of cleansers, wound gels, and other topically applied products used prior to or in combination with the particular enzymatic agent to be used.

Silverstein, P., Ruzica, F.J., Helmkamp, G.M., Lincoln, R.A., Jr. and Mason, A.D.;Surgery 73 (1), pp. 15-22, 1973.
Nanney, L.B., Fortney, D.Z., and Durham, D.R.; Wound Repair and Regeneration, 3(4), pp. 442-448, 1995.
Levine, N., Seifter, E. and Levenson, S.M.; Surgical Forum, 22, pp. 57-58, 1971.
Levine, N., Seifter, E., Connection, C., and Levinson, S.M.; Plastic and Reconstructive Surgery; 52 (4), pp. 413-423, 1973.
Bradford, M.M, Analytical Biochemistry, 72, pp. 248-254, 1976.

Return to Main Page, Wound Care Institute Newsletter, Fall 1996