Drugs are administered in different dosage forms after converting them into suitable formulations. Every dosage form is the combination of the drug and different kind of non drug component called additives. Additives are used to give a particular shape to the formulation, to increase its stability and palatability as well as to give more elegance to the preparation.

Transformation of drug into different dosage form is done for these reasons:
1. To protect the drug substance from oxidation, hydrolysis and reduction e.g coated tablets and sealed ampoules.
2. To protect the drug from the destructive effect of gastric juice (HCl) of the stomach after oral administration e.g. enteric coated tablets.
3. To provide a safe and convenient delivery of accurate dosage.
4. To conceal the bitter salty or obnoxious taste or odour of a drug substance e.g. capsules, coated tablets, and flavoured syrups etc.

And many other reasons why drugs are not given in their original state.