A Water Resistant Film Forming Emulsion - The First Steps towards a Topical Preventive Product against Intertriginous Dermatitis

Sammanfattning: Intertriginous dermatitis (Intertrigo) is a skin disease caused by friction between adjacent skin surfaces. Heat and moisture induces an inflammation, causing pain and often secondary infections. The aim of this degree project was to develop a prototype for a topical film forming emulsion for patients suffering from Intertrigo. The prototype should deposit a film on epidermis which decreases friction between the skin surfaces and prevents inflammation. The aim was to develop an in-shower product which deposited the film during the shower procedure. Two product prototypes were evaluated. One had a microcrystalline wax as the main ingredient in the oil phase and the other used a polyamide as the film forming agent. A reference cream with no film forming ingredient was used as control in the evaluative experiments. Focus was to develop and evaluate the deposited film. The film has been characterised considering its occlusivity, water resistance and bioadhesion. Occlusivity was tested with a gravimetrical method. Formulations were spread as a thin film on top of hydrogels and weight loss was determined as a function of time. Water vapour flux across the film could then be calculated. The wax formulation was less permeable than the polyamide formulation. However, none of the formulations exhibited excessive occlusive behaviour. Water resistance was evaluated with a washing experiment. Roughened Poly(methyl-methacrylate) plates were used as an in vitro substitute for skin. Samples were rubbed onto the plates and washed at 170 rpm in warm water. The plates were visualised in a light microscope before and after the washing sequence. The polyamide formulation proved to be water resistant for 2 minutes and the wax formulation was still visible after 6 minutes. Bioadhesion was tested with a texture analyser. Skin samples from pig were prepared with a dermatome and attached to a probe on the texture analyser. The probe was lowered onto the surface of the formulation and withdrawn at 0,1mm/s. A control cream and water were used as references. The force needed to withdraw the probe from the sample was measured. The wax formulation exhibited the highest tensile work to separate the probe from the sample, and water the lowest. Generally, formulations with high viscosity needed more force to separate from the probe, indicating that this might influence the results.