If Arena is selling BELVIQ to at least a million patients a year, their revenue will in fact will be much higher when accounting for the purchase price adjustments.
BELVIQ Retail Monthly Estimate: $150/mo = $1,800/year/patient Eisai's Net Sales Amount (70%): $105/mo = $1,260/year/patient Arena's Average Gross (35%): $36.50/mo = $441/year/patient Arena's COGS: $6/mo = $72/year/patient Arena's Profit per patient: $369 (29% of Net Sales)
AMRN will receive 21% of Net Revenues (1% is the 5% admin fee on COGS), but AMRN does not have any additional cost, meanwhile ARNA will pay development cost (shared with Eisai)