1Q12 US Tysabri sales were $201M, +18% YoY; half of the 18% increase was attributable to volume and half was attributable to price increases: http://pharma411.visibli.com/share/ftNWk7 http://seekingalpha.com/article/547121-biogen-idec-s-ceo-discusses-q1-2012-results-earnings-call-transcript Relative to 4Q11, US Tysabri sales increased 2.5%. p.s. BIIB deserves credit for disclosing the change in unit volume as well as dollar sales; more biotech companies ought to do that.