Stock Based Compensation (Tables)

9 Months Ended

Sep. 30, 2013

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,
	2013		2012		2013		2012
Research and development — employee	$	52,492	$	95,715	$	156,247	$	289,081
General and administrative — employee		202,827		177,391		590,056		614,470
Total employee stock-based compensation	$	255,319	$	273,106	$	746,303	$	903,551

Research and development — non-employee	$	—	$	—	$	—	$	—
General and administrative — non-employee		271,594		177,617		450,880		406,109
Total non-employee stock-based compensation	$	271,594	$	177,617	$	450,880	$	406,109

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

The fair value of the stock options and warrants 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, 2013			Nine Months Ended September 30, 2012
Risk-free interest rate		1.36	%		0.61	%
Expected volatility		84.5% - 85.8	%		77.4% - 97.7	%
Expected lives (years)		5 - 6			4 - 10
Expected dividend yield		0.00	%		0.00	%

Schedule of share-based compensation, stock options, activity

Presented below is the Company’s stock option activity:

	Nine Months Ended September 30, 2013
	Number of Options (Employees)			Number of Options (Non-Employees)		Total Number of Options			Weighted-Average Exercise Price
Outstanding at January 1, 2013		3,240,850			142,143		3,382,993		$	4.17
Granted		127,176			25,000		152,176		$	2.69
Exercised		(476	)		—		(476	)	$	1.96
Forfeited or expired		(127,812	)		—		(127,812	)	$	3.09
Outstanding at September 30, 2013		3,239,738			167,143		3,406,881		$	4.15
Options exercisable at September 30, 2013		2,274,029			158,214		2,432,243		$	4.97

Schedule of unvested stock options activity

A summary of the unvested stock options as of September 30, 2013, and changes during the nine-month period then ended, are 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, 2013		1,322,389			8,929			1,331,318		$	1.69
Granted		127,176			25,000			152,176		$	1.92
Forfeited or expired		(127,812	)		—			(127,812	)	$	2.31
Vested		(356,044	)		(25,000	)		(381,044	)	$	3.58
Non-vested at September 30, 2013		965,709			8,929			974,638		$	1.66

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, 2013:

Range of Exercise Prices	Number of Options		Weighted-Average Remaining Contractual Life (years)		Weighted-Average Exercise Price		Number of Options Exercisable		Weighted-Average Remaining Contractual Life (years)		Weighted-Average Exercise Price
$1.83 - $3.00		2,123,538		8.74	$	1.99		1,212,265		8.74	$	2.04
$3.01 – $7.00		213,512		5.42	$	4.91		176,036		5.42	$	5.26
$7.01 – $8.50		937,545		4.40	$	7.66		911,656		4.40	$	7.67
$8.51 – $32.55		132,286		1.15	$	12.75		132,286		1.15	$	12.75
		3,406,881		7.04	$	4.15		2,432,243		7.04	$	4.97