Learning Objectives

• The most common medication dosage forms
• The different types of dosage forms
• The different routes of administration of each dosage form
• The need for dosage form development

A drug is defined as an agent intended for use in the diagnosis, mitigation, treatment, cure, or prevention of disease in humans or in animals. Drugs are not administered as such and they are converted into a palatable form, which is called as “dosage form.” Dosage form contains both active and inactive ingredients (excipients or additives). They act as a carrier by which drug molecules are delivered to sites of action within the body. Inactive ingredients give shape to the formulation; increase its efficacy, stability, and palatability; and impart elegance to the preparation. The route of administration for drug delivery is dependent on the dosage form of the drug substance. Various dosage forms may exist for a single drug, since different medical conditions need different routes of administration.

A drug is converted into a dosage form for the following reasons:

1. To protect the drug from oxidation, hydrolysis, reduction, and other environmental factors
2. To protect the drug from the destructive effects of the gastric juice of the stomach after oral administration; for example, enteric coated tablets
3. To provide a safe and convenient delivery of accurate dosage
4. To mask the bitter, salty, or obnoxious taste or odor of a drug substance
5. To provide the optimum drug action through a suitable therapy; for example, inhalation aerosols and inhalants
6. To administer the drug into one of the body cavities; for example, rectal suppositories
7. To deliver maximum drug action from topical administration sites; for example, creams, ointments, and ophthalmic preparations
8. To provide sustained and controlled release action, thereby reducing dosing frequency; for example, sustained release tablets, capsules, and suspensions
9. To provide liquid dosage form of the drugs soluble in a suitable vehicle, for example, solutions.