Purchased Patents

3 Months Ended

Mar. 31, 2012

Purchased Patents

Purchased Patents

5. Purchased Patents

In connection with a purchase agreement with Shire Laboratories, Inc., the Company acquired certain patents in 2005.  The following sets forth the gross carrying amount and related accumulated amortization of the patents (in thousands):

		December 31, 2011				March 31, 2012
						(unaudited)
	Weighted- Average Life	Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
		(in thousands)
Purchased patents	10.0	$	2,292	$	1,380	$	2,292	$	1,437

Amortization expense for the three months ended March 31, 2011 and 2012 was approximately $57,000 each period. The net book value of intangible assets as of March 31, 2011 and 2012 was approximately $0.9 million and $0.9 million, respectively.