Preparation of Ointments, Pastes, Creams and Gels

Preparation of ointments

Ointment preparation: Prepare the ointment as follows:

1. All components of the base are uniform, meaning there are no lumps of high melting point constituents, liquids do not separate, and insoluble powders are evenly dispersed throughout.
2. Grittiness is absent, namely finely divided insoluble powders, and large lumps of particles are not present. This requires precision in preparation methods.

Ointments are commonly made by mixing two techniques:

1. Fusion is one of the methods for ensuring homogeneity, in which the ingredients are melted together.
2. Grinding together finely divided soluble substances with a small amount of a basis or one of its ingredients and then diluting with gradually increasing amounts of the basis to evenly disperse the soluble components.

Fusion method for preparing ointments

All solid ingredients included in cremes or ointments, such as beeswax, cetyl alcohol, stearyl alcohol, stearic acid, paraffin, etc. should be melted before application to prevent burning. 

The melting can be accomplished in two ways:

Method I

Melting the components is done in order of decreasing melting points, which means that the substances with the highest melting points should be melted first, the substances with the next melting points, and so on. When the medicament is added to the ingredients in a liquid form, a thorough stirring is carried out until the mixture cools down and becomes homogenous.
Advantage
Substances with low melting points will be protected from overheating in this way.

Method II

Substances with low melting points will be protected from overheating in this way.
Advantage
There was a lower maximum temperature reached and a shorter reaction time compared to Method-I, possibly because substances with low melting points acted as solvents on the other components.

Cautions

1. As components melt (beeswax, wool alcohols, paraffin, higher fatty alcohols, emulsifying waxes), waxy components are ground by stirring and the dish is lowered so that the highest surface area is heated.
2. Various ingredients may discolor as a result of oxidation, such as the fat and alcohol in wool, and these discolored surfaces need to be cleaned before use.
3. When ointment is cooled, stir it thoroughly until it has completely set, taking care not to cause localized cooling, for example, by using a cold spatula or transferring the dish to a cold container before it has set completely. In case these precautions are ignored, hard lumps will not separate.
4. In addition, vigorous stirring causes excessive aeration, so it should not be done after the ointment is thickened.
5. Ointment bases are greasy, so many of the constituents tend to pick up dirt while being stored, which can be observed after melting. In both cases, after allowing the melt to sediment, the supernatant is decanted, or the muslin is passed through a warm strainer with support. Once melted, the clarified liquid is collected in a second bowl hot enough to collect it.
6. As a result of the separation of the ingredients that compose the high M.P. of the product, it becomes granular after cooling. The product should be remelted, with the minimum amount of heat, and stirred once more.

Preparation of pastes

To make pastes, you must grind them and fuse them, just like ointments. Typically, liquid or semisolid bases are triturated. For bases that are semisolid or solid, the Fusion method must be used.

Preparation 1

Formula	Quantity
The Zinc oxide. It is finely sifted	25 g taken as a sample
A Starch - finely sifted	25 g taken as a sample
The White soft paraffin	50 g taken as a sample

This preparation consists of a semi-solid paste formed by fusion and trituration.
Procedure

• The starch powder and zinc oxide are filtered through sieve no. 180.
• A water bath is used to melt soft paraffin.
• It is required to take the required amount of powder in a cold mortar, mix with melted base, and triturate until smooth. A cooling process is then performed to mix in the remaining base.

Preparation 2

Zinc oxide, finely sifted

Coal tar

Emulsifying wax

Starch

Yellow soft paraffin

Type of preparation - The paste is made by fusing semi-solid components.

Procedure:

Method I

A tared dish is used to melt emulsifying wax (70 degrees C)
A dish is used to weigh coal tar. Mixed.

Melted paraffin is added to the tar-wax mixture after it has been melted in a separate dish (70 degrees C). Mix until well combined. To make sure everything is blended well, give it one last stir.

The mixture was allowed to cool at about 300°C, and the mixture was combined with zinc oxide (previously filtered through 180 meshes) and starch. The mixture was then cooled.

Method II

It was melted together with paraffin, blended well, and stirred until almost set. On a warm tile, the powder and tar are mixed. This eliminates the possibility of overheating the tar.

Preparation of creams

Trituration

When adding finely divided insoluble powders or liquids, geometric dilution is used. When adding liquids, a well is made into the center. To avoid air pockets, we used glass slabs when smaller quantities were needed. Large quantities of powder were ground with a mortar and pestle.

Levigation

Adding coarse particles that are insoluble, this is also referred to as "wet grinding". A molten liquid base, a liquid base, or a semisolid base is used to rub coarse powder. The shearing force must be considered to avoid grittiness.

Fusion method

In the fusion technique, drugs and other solids are dissolved in an ointment base and then combined. By melting the ingredient into the base, the soluble constituents are dissolved. After speculation or trituration, the congeal mixture is smoothed out. Fusion uses special techniques to ensure that the base and other components will not be damaged by thermal degradation.

Preparation of gels

Three methods can be used:

Cold method

After cooling water to 4 to 100 degrees, it was poured into a mixing vessel. The peeling agent was added slowly and agitated until the complete solution was reached. Temperatures below 100 °C were maintained during the melting process. A solution of the drugs was slowly added while mixing gently. The liquid should be transferred to a container and allowed to warm to room temperature, where it will become a clear gel.

Dispersion method

Stirring the gelling agent in water at 1200 rpm for 30 minutes dispersed the gelling agent. The nonaqueous solvent was used to dissolve the drug. The preservative was also added. Continuous stirring was performed while adding this solution to the gel above.

Fusion method

This method involves the use of various waxy materials as gallant in a non-polar medium. In this method, waxy materials are melted and drugs are added. A uniform gel was formed by stirring slowly until it was dissolved.

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