Pharmaceutical companies generally produce large numbers of compounds in the research phase for which it is impractical to use often long and cumbersome systematic chemical names, and for which the effort to generate nonproprietary names may not be warranted, see article on drug nomenclature.
Three main methods are found for prefixing the numeric identifier – with a space (gap),[1] with nothing (concatenated),[2][3] and with a dash (or hyphen).
[4] For example, ABT-199 is a compound developed at Abbott Laboratories, and this name has been used in early publications of research results.
A long list of code designations with corresponding trade names can be found in Appendix IV of the USP Dictionary, see article on drug nomenclature.
For example, the letter code may reflect a therapeutic/disease area or an internal project name.