STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating activities
Net loss	$ (38,048)	$ (32,354)	$ (25,966)
Adjustments to reconcile net loss to net cash used in operations:
Stock-based compensation	5,310	3,435	2,116
Accretion of interest expense	1,680
Amortization of debt financing costs	17
Depreciation and amortization of property and equipment	27	3	6
Changes in operating assets and liabilities:
Trade receivables	(557)
Inventory	(4,663)
Prepaid expenses and other current assets	(480)	278	135
Other assets	11	72	(23)
Accounts payable	193	2,794	(453)
Accrued clinical expenses	199	(171)	106
Accrued compensation and other liabilities	275	(1,457)	1,794
Deferred revenue	16
Net cash used in operating activities	(36,020)	(27,400)	(22,285)
Investing activities
Purchases of property and equipment	(151)	(25)
Net cash used in investing activities	(151)	(25)
Financing activities
Proceeds from issuance of common stock and warrants, including collection of stockholder notes receivable, net of cash paid for issuance costs	59,708	42,482	23,002
Proceeds from issuance of long-term obligation, net of cash paid for issuance costs	29,860
Principal payments of obligations under capital leases			(6)
Net cash provided by financing activities	89,568	42,482	22,996
Net increase in cash and cash equivalents	53,397	15,057	711
Cash and cash equivalents at beginning of period	39,635	24,578	23,867
Cash and cash equivalents at end of period	$ 93,032	$ 39,635	$ 24,578