The sharp decline from 3Q10 to 4Q10 was presumably due in part to channel destocking. More important, Dysport continues to be a very distant second to Botox, which had worldwide 4Q10 sales of $386M.
After adding in US sales of Dysport for cosmetic indications, which are booked by MRX, Botox is outselling Dysport worldwide by about 4:1.