LIQUID DISPERSION 1. Basic Competencies Students are able to carry out administrative reviews of recipes and pharmaceutical suitability as well as make liquid dispersion preparations, namely emulsions and suspensions. 2. Practicum Objectives This practicum aims to introduce the types of liquid dispersion recipes (emulsions and suspensions) and train practitioners to study recipes and make the preparations into appropriate forms. 3. Description of Theory A. Emulsion Emulsions are preparations containing liquid medicinal substances or drug solutions, dispersed in a carrier liquid, stabilized with a suitable emulsifying agent or surfactant. An emulsion is a preparation containing two immiscible substances, usually oil and water, where one liquid is dispersed into small droplets in the other liquid. Emulsion type, consisting of: 1. Water-in-oil (W/O) type emulsion orwater in oil(W/O) or also called water type, where water is evenly dispersed in the oil solution. 2. Oil-in-water (O/W) type emulsion oroil in water(O/W) or also called oil type, where the oil is evenly dispersed in a water solution. In the emulsion boundary, the dispersed phase is considered as the inner phase and the dispersion medium as the outer phase or continuous phase. Because the outer phase of the emulsion is continuous, the O/W emulsion can be diluted or added with water. Generally, to make a stable emulsion, a third phase of the emulsion is needed, namely an emulsifier/emulgator. Types of emulsifiers include: 1. Natural emulsifiers, for example: nuts and egg yolks 2. Artificial emulsifiers, for example: fatty oil, paraffin liquidum, solid fat/cera, tragacanth, tween and span, PGS, agar-agar, CMC, and sapo.Emulsions are composed of the following components: 1. Nutrient ingredients/substances (in the form of liquid) 2. Emulsifying agent 3. Preservative 4. Antioxidant substances 5. Flavoring and coloring substances In small sizes, emulsion preparations in pharmacies can be made using three commonly used methods. The three methods are: 1. Dry gum method or continental method, the emulsifying agent (usually gum) is mixed with oil before adding water. This method is also known as the 4:2:1 method because for every 4 parts (volume) of oil, 2 parts of water, and 1 part of gum are added to make the main emulsion or initial emulsion. 2. English method or wet gum method, an emulsifier is added to water (where the emulsifier dissolves) to form a mucilage, then the oil is slowly mixed to form an emulsion. The proportions of oil, water, and gum are the same as the dry gum method, but the mixing order is different and the ratio of ingredients can be varied during the preparation of the primary emulsion. 3. The bottle method or Forbes bottle method, is used for evaporated oils and less viscous oils and is a variation of the dry gum method. B. Suspension Suspension is a liquid preparation containing solid drug ingredients in fine and insoluble form, dispersed in a carrier liquid. The dispersed substance must be fine, must not settle quickly and when shaken slowly the sediment must immediately disperse again. A suspension is a heterogeneous liquid preparation consisting of two phases (solid and liquid) and one phase is insoluble and dispersed in the other phase. The suspension is composed of the following components: 1. Active substance (insoluble solid) 2. Carrier (water) 3. Suspension agent 4. Preservative 5. Antioxidants 6. Coloring, smell and taste Suspension agents are used to increase viscosity and slow down the settling process. The formulator must select suspending agents singly or in combination and at the right concentration. The following is an example of a suspending agent: - Tragacant 1-2% - Starch 2% - Sodium alginate 1-2% - Cellulose metal 0.5-2% - Na CMC 0.25-2% - Bentonite 2-5% - CMC 0.5-2% - Veegum 0.5-2% - Gum Arabic (powder + 2gr/100mL, mucilage 10-20mL/150mL) The most commonly used suspension preparation method is the dispersion method. Preparation is made by adding medicinal powder to the mucilage that has been formed, then diluting it.Another manufacturing method, namely by precipitation, is done by first dissolving the drug powder to be dispersed in an organic solvent which will be mixed with water. After the drug powder has dissolved into the organic solvent, it is diluted with a suspension solution in water so that a fine precipitate will form which is suspended with the suspension material. These organic solvents can be ethanol, propylene glycol, and polyethylene glycol. Most suspensions should be stored in tightly closed containers and protected from freezing, excessive heat, and light. The suspension needs to be shaken each time it is used to ensure even distribution of the solids in the vehicle so that the dose administered each time is precise and uniform.