Stock Based Compensation (Tables)

9 Months Ended

Sep. 30, 2012

Stock Based Compensation [Abstract]

Schedule of total stock-based compensation expense from stock options and warrants

The following table sets forth the total stock-based compensation expense resulting from stock options and warrants included in the Company's unaudited interim statements of operations:

	Three Months Ended September 30,					Nine months Ended September 30,
	2012		2011			2012		2011
Research and development — employee	$	95,715	$	80,581		$	289,081	$	251,902
General and administrative — employee		177,391		202,957			614,470		744,231
Total employee stock-based compensation	$	273,106	$	283,538		$	903,551	$	996,133
Research and development — non-employee	$	—	$	10,246		$	—	$	51,730
General and administrative — non-employee		177,617		(11,657	)		406,109		76,651
Total non-employee stock-based compensation	$	177,617	$	(1,411	)	$	406,109	$	128,381

Schedule of share-based payment award, fair value of the stock options granted , assumptions

During the nine-month period ended September 30, 2012, the Company issued stock options to purchase 53,502 shares of its common stock. The fair value of the stock options granted in the current nine-month period was estimated using the Black-Scholes option-pricing model, based on the following assumptions:

	Nine months Ended September 30, 2012			Nine months Ended September 30, 2011
Risk-free interest rate		1.54	%		2.05	%
Expected volatility		89.7% - 97.7	%		87.7% - 90.0	%
Expected lives (years)		6 - 10			6
Expected dividend yield		0.00	%		0.00	%

Schedule of share-based compensation, stock options, activity

As of September 30, 2012, there remained approximately $0.9 million of unrecognized compensation expense related to unvested stock options granted to current and former employees, directors and consultants, to be recognized as expense over a weighted-average period of 0.98 years. Presented below is the Company's stock option activity:

	Nine months Ended September 30, 2012
	Number of Options (Employees)			Number of Options (Non-Employees)			Total Number of Options			Weighted-Average Exercise Price
Outstanding at January 1, 2012		1,763,923			143,572			1,907,495		$	6.06
Granted		53,502			—			53,502		$	2.77
Exercised		(1,071	)		(1,429	)		(2,500	)	$	2.88
Forfeited or expired		(38,528	)		—			(38,528	)	$	4.52
Outstanding at September 30, 2012		1,777,826			142,143			1,919,969		$	5.97
Options exercisable at September 30, 2012		1,314,592			124,286			1,438,878		$	6.82

Schedule of unvested stock options activity

A summary of the unvested stock options as of September 30, 2012, and changes during the nine-month period then ended, is presented below:

	Number of Options (Employees)			Number of Options (Non-Employees)		Total Number of Options			Weighted-Average Grant Date Fair Value per Share
Non-vested at January 1, 2012		693,504			17,857		711,361		$	3.28
Granted		53,502			—		53,502		$	2.32
Forfeited or expired		(38,528	)		—		(38,528	)	$	3.50
Vested		(245,244	)		—		(245,244	)	$	3.38
Non-vested at September 30, 2012		463,234			17,857		481,091		$	3.08

Schedule of share-based compensation, summarizes significant ranges of outstanding stock options

The following table summarizes significant ranges of outstanding stock options under the Company's plans at September 30, 2012:

Range of Exercise Prices		Number of Options		Weighted-Average Remaining Contractual Life (years)		Weighted-Average Exercise Price		Number of Options Exercisable		Weighted-Average Contractual Life		Weighted-Average Exercise Price
$	1.96 - 3.00		631,075		8.57	$	2.29		281,401		8.57	$	2.42
$	3.01 –7.00		202,799		5.61	$	5.39		196,037		5.61	$	5.40
$	7.01 –8.50		944,688		5.38	$	7.66		826,600		5.38	$	7.72
$	8.51 – 32.55		141,407		2.08	$	12.75		134,840		2.08	$	12.75
			1,919,969		6.20	$	5.97		1,438,878		6.20	$	6.82