ViroPharma has agreed to acquire fellow USA-based form Lev Pharmaceuticals in a move that will give it access to the latter’s new drug Cinryze for hereditary angioedema disease.

Cashwise, ViroPharma will pay out at least $442.9 million, which equates to $2.25 per share in cash and $0.50 per share in stock. The total price of $2.75 a share represents a 49% premium to Lev's closing price on Monday.

The firms noted that Lev stockholders could receive up to an additional $1.00 per share on reaching “certain regulatory and commercial milestones”, which means that the deal could be worth up to $617.5 million. ViroPharma has also purchased $20 million of Lev stock.

The reason ViroPharma is paying out this sizeable sum is Cinryze (C1 inhibitor [human]), which is currently under regulatory review at the US Food and Drug Administration as a replacement therapy for patients with HAE, also known as C1 esterase inhibitor deficiency. It is “a dangerous and potentially deadly inflammatory disease affecting up to 10,000 patients in the USA”, noted ViroPharma, and studies have shown that Cinryze can “significantly reduce the severity, duration and frequency of HAE attacks”.

The addition of Cinryze to its late-stage pipeline is a big boost for ViroPharma which is facing possible generic competition later this year to its lead product, the antibiotic Vancocin (vancomycin).