Formulation and Evaluation of Vanishing Cream: Vanishing Creams are oil in the type of emulsion. When applied on the surface of the skin, they spread thin oil-less film which is not visible to the naked eye. Hence, they are called vanishing creams. They are used to hold powder on the skin as well as to improve adhesion.
Properties of Vanishing Creams
1. It should have a high melting point.
2. It should be pure white.
3. It should possess very little odor.
4. It should have less iodine.
Use of Glycerin in Vanishing Cream
1. Helps to soften and protect the skin and prevent chaps.
Ingredients of Vanishing Creams
Method of Preparation of Vanishing Creams
1. Stearic acid melted in a container by using a water bath.
2. Potassium hydroxide dissolved in water and glycerine is added and heated to the temperature of 75°C. This is called the aqueous phase.
3. Slowly aqueous phase is added to the melted stearic acid
4. Perfume is added to the preparation when it attains 40°C.
Evaluation of Vanishing Creams
Evaluation of Vanishing creams is carried out by the following methods:
1. In-vitro method, and
2. In-vivo method.
1. In-Vitro Method of Evaluation:
Tests are carried out to know the performance of the product. Various instruments have been used by the investigator to evaluate the effect of temperature and humidity.
Various instruments used in the in-vitro method are as follows:
(a) Tensile strength tester
(b) Hargen’s Gas Bearing Electron dynamometer (GBE)
(c) Occlusive potential of the ingredient
(d) Gravimetric analytical method
(e) Thermal analytical method
(f) Electrical methods.
(a) Tensile strength tester: This method is useful for determining the tensile property of the exercised stratum corneum of the skin. The stress or strain characteristics of stratum corneum obtained from various sources can be studied by using this instrument.
(b) Hargen’s gas-bearing electro dynamometer: It determines the visco-elastic behavior of the skin. It also determines the effect on the skin. It is used both in-vitro and in-vivo tests.
(c) Occlusive potential of ingredient: The occlusive potential of raw materials or ingredients used in the formulation of the creams, are determined by knowing the water diffusion rate.
(d) Gravimetric analytical method: This method helps establish a relationship between water content present in stratum corneum and relative humidity. This is done by suspending bits of callus.
Water content = Dry weight of the tissue – Equilibrium value.
(e) Thermal analytical methods: Various thermal analytical methods are used to provide information about the effect of temperature which causes a change in the stratum corneum.
(f) Electrical methods: Various electrical properties such as capacitance, impedance, and dielectric constant are measured by electrical methods to provide information about the variation in the water content present in the stratum corneum of the skin.
2. In-Vivo Method of Evaluation:
(b) Scanning Electron Microscopy (SEM)
(c) Optical Microscopy and Macrophotography
(d) Skin friction
(e) Sensitivity test.
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