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?
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: