In particular, the unexpected appearance in early 1998 of a more thermodynamically stable form (Form II) of ritonavir (Norvir, Abbott Laboratories, protease inhibitor for the treatment of HIV), with different dissolution properties compared to those of the earlier commercial Form I. Form II is <50% as soluble as Form I, resulting in the observed poor dissolution behavior and eventual withdrawal of the capsule from the market. This incident had serious implications for the marketed product and the patients receiving the drug. The project was suspended until a modified procedure was found. Renitidin, sertraline, and frentizole are some important examples of pharmaceuticals that exhibit polymorphism.This is from this OPRD ASAP; they were dealing with a similar issue. They have ultimately performed some 3600 recrystallization before they found the right one.
Reminds me how easy my life is and how badly I suck at recrystallizations.