Drug Formulation: An Overview of Types and Applications

The formulation of a drug is critical to the effectiveness of its delivery and is specifically chosen by the pharmaceutical manufacturer for the most positive outcome. Pharmaceutical formulations come in a variety of types that can be broken into larger categories based on their method of application. These main categories include oral, topical, nasal, ophthalmic and intravenous formulations. Choosing the proper formulation for a new drug is based on a variety of factors, primarily absorption and the target of the drug.

Some of the most common medications come as oral formulations, which include softgels, tablets and solutions. Solutions are typically used in situations where speed of delivery is a priority, such as medications that treat cold and cough symptoms. An additional benefit of oral solution formulations is ease of ingestion for sensitive or delicate systems, such as those of children or the elderly. Tablets are a standard formulation for water-soluble medications with stable structures due to their convenient storage and ingestion. Softgels are often used for drugs that best absorb in mixed alcohol or glycerol mixtures.

Topical formulations are applied directly to the skin, while ophthalmic formulations are given to the eye. Nasal application, often used for sinus problems, is also used in situations that require the most rapid delivery. Intravenous injections, though not as frequently used in commercial medications, are the preferred method of delivery for patients already in hospitals or for certain long-term treatments such as insulin.

Determining the best formulation for a new pharmaceutical is done through a complex series of formulation studies. These studies review a series of factors that contribute to the bioavailability of the drug, which is the way the body absorbs the medication. Some of the attributes that are crucial to proper formulation are particle size, solubility, pH and stability. Once the physical factors of the new drug have been accounted for, commercial and consumer factors must be addressed, including the shelf stability, appearance and ease of consumption of the drug.

Specific targets for a drug may require unusual formulations. Some drugs that are intended for use in a wider range of situations may come in a variety of formulations for ease of application. This is particularly useful when medications are adapted for use with children, as liquid solutions are easier and quicker to ingest. Finding the best formulation for a drug ensures that it will be as effective and successful as possible.