Net Loss Per Share (Tables)

3 Months Ended

Mar. 31, 2013

Calculation of Historical Outstanding Dilutive Securities Not Included in Diluted Loss per Share

Historical outstanding dilutive securities not included in the diluted loss per share calculation are as follows:

	March 31,
	2013		2012
Outstanding options to purchase common stock		5,356,086		4,167,184
Warrants to purchase common stock		609,016		609,016
Total		5,965,102		4,776,200