Ritonavir production at an alternative factory in Italy initially passed dissolution tests.

A tiny bit of Form II ritonavir acted as a nucleation site, lowering the activation energy and causing all Form I to crystallize into Form II, with seed crystals spreading through the air.

There are at least five known forms of ritonavir, not just two.

Ritonavir was introduced in 1996 to treat HIV.

Abbott needed to halt all production of ritonavir immediately due to the quality control issues.

Abbott stated that the semi-solid formulation of ritonavir began to change into a crystal form, a transformation they believed was a scientific and chemical impossibility.