Pharmaceutics Lab Practical 2
Pharmaceutics Experiment 2 Preparation of a Hand Cream
OBJECTIVE
1.
To learn the method of preparing a hand cream.
2.
To appraise the function of the ingredients in the hand cream.
BACKGROUND
Cream is a kind of dosage form and particularly hand cream is formulated to carry out a variety of cosmetic functions. Among these are softening and moisturizing the skin; elimination of natural waste products (oils) by emulsification; and cooling the skin by radiation, thus helping to maintain body temperature. In addition, hand cream must have certain ingredients that aid spreadability and provide body emollient. In many cases added fragrance can improve the odor, and in some special cases medications treat various skin diseases.
The basic hand cream formulations all contain water to provide moisture and lanolin, which helps its absorption by the skin. The latter is a yellowish wax. Chemically, wax is made of esters of long-chain fatty acids and long-chain alcohols. Lanolin is usually obtained from sheep wool; it has the ability to absorb 25–30% of its own weight of water and to form a fine emulsion. Mineral oil, which consists of high-molecular-weight hydrocarbons, provides spreadability. In order to allow non-polar substances, such as lanolin and mineral oil, to be uniformly dispersed in a polar medium, water, one needs strong emulsifying agents. An emulsifying agent must have non-polar, hydrophobic portions to interact with the oil and also polar, hydrophilic portions to interact with water. A mixture of stearic acid and triethanolamine, through acid-base reaction, yields the salt that has the requirements to act as an emulsifying agent.
Besides the above five basic ingredients, some hand creams also contain alcohols, such as propylene glycol (1,2-propanediol), and esters, such as methyl stearate, to provide the desired texture of the hand cream.
In this experiment you will prepare four hand creams using the combination of ingredients as shown in Table 1.
Table 1
OBJECTIVE
1.
To learn the method of preparing a hand cream.
2.
To appraise the function of the ingredients in the hand cream.
BACKGROUND
Cream is a kind of dosage form and particularly hand cream is formulated to carry out a variety of cosmetic functions. Among these are softening and moisturizing the skin; elimination of natural waste products (oils) by emulsification; and cooling the skin by radiation, thus helping to maintain body temperature. In addition, hand cream must have certain ingredients that aid spreadability and provide body emollient. In many cases added fragrance can improve the odor, and in some special cases medications treat various skin diseases.
The basic hand cream formulations all contain water to provide moisture and lanolin, which helps its absorption by the skin. The latter is a yellowish wax. Chemically, wax is made of esters of long-chain fatty acids and long-chain alcohols. Lanolin is usually obtained from sheep wool; it has the ability to absorb 25–30% of its own weight of water and to form a fine emulsion. Mineral oil, which consists of high-molecular-weight hydrocarbons, provides spreadability. In order to allow non-polar substances, such as lanolin and mineral oil, to be uniformly dispersed in a polar medium, water, one needs strong emulsifying agents. An emulsifying agent must have non-polar, hydrophobic portions to interact with the oil and also polar, hydrophilic portions to interact with water. A mixture of stearic acid and triethanolamine, through acid-base reaction, yields the salt that has the requirements to act as an emulsifying agent.
Besides the above five basic ingredients, some hand creams also contain alcohols, such as propylene glycol (1,2-propanediol), and esters, such as methyl stearate, to provide the desired texture of the hand cream.
In this experiment you will prepare four hand creams using the combination of ingredients as shown in Table 1.
Table 1