Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Total revenue	$ 10,026	$ 14,853
Cost of sales	5,241	4,898
Gross profit	4,785	9,955
Operating expenses:
Research and development	3,998	6,480
General and administrative	3,595	3,219
Sales and marketing	1,364	1,366
Total operating expenses	8,957	11,065
Loss from operations	(4,172)	(1,110)
Interest expense	(211)	(211)
Other income, net	127	44
Net loss and comprehensive loss	$ (4,256)	$ (1,277)
Net loss per common share, basic and diluted	$ (0.25)	$ (0.09)
Weighted-average shares used to compute net loss per common share, basic and diluted	17,097,999	14,789,036
Product sales
Total revenue	$ 9,023	$ 9,365
Product sales
Total revenue	9,023	9,365
Licensing, royalty and other revenue
Total revenue	$ 1,003	$ 5,488