The following are the advantages of using emulsions as dosage forms:

1. Unpalatable oils can be administered in a palatable form.
2. The aqueous phase is easily flavored.
3. The taste of oils can be masked.
4. Absorption is faster when compared to solid dosage forms.
5. It is possible to include two incompatible ingredients, one in each phase of the emulsion.
6. Emulsions of the O/W type are administered orally for the following purposes:
   1. Disguise the taste or oiliness of medicinal oils such as liquid paraffin and cod liver oil. The aqueous continuous phase, which will be pleasantly flavored, isolates the unpleasant disperse phase from the tongue and, if the patient wishes, allows the residue of the dose to be rinsed easily from the mouth with water.
   2. To improve the absorption of oils
   3. Sometimes O/W emulsions of nutritive oils and fats are administered intravenously to patients who are unable to ingest food in the normal way.
7. Semisolid emulsions are O/W (vanishing creams) or W/O (cold creams). O/W emulsions are preferred over W/O emulsions. They can be easily rubbed into the skin and can be easily removed by washing.

The following are the disadvantages of using emulsions as dosage forms:

1. Calculation of primary emulsion formulae and technical expertise are needed for the manufacture of stable emulsions.
2. A measuring device is needed for administration.
3. Emulsions require shaking before use to ensure uniformity of dose.
4. If the preparation is not shaken well, the accuracy of dose is likely to be less when compared to solutions.
5. Improper storage conditions can affect the disperse system.
6. Since emulsions are stored in glass or plastic containers, they are bulky, difficult to transport and prone to container breakages.
7. Microbial contamination of emulsions can lead to cracking.

Learning Objective

• Tests that can be carried out to identify emulsion type

The tests that can be performed to distinguish between O/W and W/O emulsions are given below (Table 6.7):

1. Dilution test
2. Dye solubility test
3. Conductivity test
4. Cobalt chloride test
5. Fluorescence test

Table 6.7 Tests to distinguish between O/W and W/O Emulsions

Sl. No.	O/W Emulsion	W/O Emulsion