![Catalyst shares dive amid speculation about 'off-label' rare disease rival](/sites/default/files/styles/x_large/public/default_images/empty.jpg?itok=C-Mgnvzj)
Catalyst shares dive amid speculation about 'off-label' rare...
Shares in Catalyst Pharmaceuticals have dived after the US regulator approved a potential competitor to its rare disease drug Firdapse, which has been at the centre of a drug pricing row.