Small Molecules - Really, Really Small

Mentioning such a small compound as pirfenidone prompts me to put up the graphic shown below: these are the smallest commonly used drugs that I can think of. (OK, there's cocaine as a nasal anaesthetic - no, really - but that's where I draw the line at "commonly used". Nominations for ones that I've missed are welcome, and I'll update the list as needed. Note: four more have been added since the initial post, with more to come. This sort of thing really makes a chemist think, though - some of these compounds are very good indeed at what they do, and have been wildly successful. We need to keep an open mind about small molecules, that's for sure, no matter how small they are. Update: see this follow-up post for the latest version of the graphic.
Source: In the Pipeline - Category: Chemists Tags: Drug Industry History Source Type: blogs