2005 Symposium on Advanced Wound Care | |
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Laboratory Research
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Rheological characterization of several enzymatic debridement formulations. D.W. Brett, BS, BS, MS, Smith & Nephew, Largo, FL During development of topically applied agents, it is key to gain insight into the ease of use, efficacy and stability of various formulations. But how does one gain this insight? Rheological profiles help provide insight. In oscillation mode, the level of applied stress required to start the movement of the formulation & how quickly the emulsion “breaks” is determined. Prior to movement, the slope of the curve is ~ zero, but decreases as the emulsion is broken. When and how quickly the slope drops below zero is a direct measurement of the ease of spreadibility. In flow mode, the relationship between the externally applied stress & resultant sheer rate of the formulation is described. The behavior of the emulsion under a constant stress is determined and the viscous (flowable) characteristic of the emulsion is evaluated. In frequency mode, the stability of an emulsion, which is key to the shelf life and performance of the agent, is evaluated. Using rheology is was possible to evaluate and gain valuable insight into ease of use, efficacy and stability of the formulations under test. Rheology is a valuable new tool in the development of topically applied agents. |
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