Papain-Urea is an enzymatic debrider typically used when significant debridement is required.  It works by digesting the proteinaceous components of necrotic tissue, resulting in a clean wound bed.  Enzymatic debridement produces therapeutic benefits and is associated with reduced infection and lower risks of hospital re-admission.  Papain-urea has been shown to be faster and more effective in debriding wounds and promoting healing than other enzymatic treatments.  There are numerous papain-urea products on the market, some of which have been available for over 50 years.  All of the products contain similar concentrations of papain and are frequently used interchangeably.  Recently, a novel Papain-Urea Aerosol Foam formulation demonstrating robust enzymatic activity was introduced.  In order to compare the kinetics of protein digestion of the Papain-Urea Aerosol Foam with that of the leading Papain-Urea Ointment, the activity of the papain-urea products was examined in an in vitro wound model.  The model replicates a wound environment by presenting a fully hydrated substrate matrix containing embedded protein.  The embedded protein is degraded by the papain to form a zone of clearance allowing measurement of activity as a function of time at 30, 60, and 90 minutes, 2 hours and 4 hours.  The results indicate that the Papain-Urea Aerosol Foam formulation demonstrated the fastest rate of clearance and the greatest extent of clearance at 4 hours.  While not comparing the clinical efficacy of the papain-urea debriders, the results of this study suggest that differences in enzymatic activity might influence clinical outcome.