Arena reported $1.3 million in Belviq net product sales in the second quarter, which is 31.5% of the $4.1 million in net product sales recorded by Eisai.

Belviq hit pharmacy shelves in the beginning of June, so it's only about a month of sales in the second quarter. Still, $4.1 million in net product sales is light, especially considering that number includes inventory stocking.

Belviq's reported net sales underwhelmed, in part, because Eisai is giving away tons of free samples--an estimated 60-70% of all Belviq prescriptions filled are gratis. Separately, Eisai reported $10 million in gross sales of Belviq, which means the gross-to-net discount was a huge 60%.