Jane Yen Revollo, M.S.

University of North Carolina at Chapel Hill

Claire, TN, US

In my pharmacology class, I noticed that many generic drug names have words after the name (e.g., morphine sulfate and potassium bromide). I know the words are derived from the molecular structure of the drug, but I was wondering what they mean exactly. Is there a pharmacokinetic or pharmacodynamic significance (e.g., sulfates are minimally protein bound and chlorides have a short onset)? Can a drug have multiple forms (e.g., morphine sulfate and morphine phosphate)? Also, what is the name for this collective group of words?

Jane Yen Revollo
University of North Carolina at Chapel Hill,
former HHMI predoctoral fellow
The words after the generic name of the drug indicate the salt form of that drug. Drugs can be administered in many different ways, for example, orally, topically (onto the skin), subcutaneously (injected just under the skin), or intravenously. To be effective, the drug needs to be absorbed into the body and go to the right organ or cells where the drug has its effect. Sometimes, however, the chemical properties of the drug prevent it from being appropriately absorbed. To fix this problem, scientists at pharmaceutical companies can convert the drug molecule into an ion (a form of the molecule with a positive or negative charge) and match the ionized drug molecule with another molecule of the opposite charge. Examples of these other molecules include sulfate or a chloride atom. This combination of the drug ion with another ion is called a salt.

A drug can be developed into many different salt forms. These different forms sometimes have different chemical and pharmaceutical characteristics. For instance, one salt form of the drug may be absorbed through the skin more effectively than other salt forms. Alternatively, a drug may be more stable and last longer on the shelf when paired with one salt compared to another. There is no hard and fast rule that the same salt form of different drugs will have similar properties, that is, chloride salts of Drug X and Drug Y may behave very differently chemically from each other. Often, multiple salt forms of a drug will be developed and researched to determine which have the best pharmaceutical properties.

For further information, check out this excellent article: Kumar, L., Amin, A., and Bansal, A.K. 2008. Salt selection in drug development. Pharmaceutical Technology. 3(32). Available at:

http://www.pharmtech.com/pharmtech/Peer-Reviewed+Research/Salt-Selection-in-Drug-Development/ArticleStandard/Article/detail/500407

05/30/12 08:57