Income taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income taxes

Schedule of significant components of deferred income tax assets and liabilities

	December 31,
	2019		2018
	(in thousands)
Deferred Tax Assets:
Net operating loss	$	37,747	$	37,819
Share-based compensation		2,113		1,757
Research and development tax credit		1,947		2,378
Other reserves		2,238		1,270
Finance lease liability		156		390
Operating lease liability		826		208
State deferred		1,518		1,236
Inventory		90		103
Accrued rebates		5,862		4,902
Interest expense carryover		1,143		1,296
Other		914		952
Total deferred tax assets		54,554		52,311
Deferred Tax Liabilities:
Intangible assets		(1,230)		(1,226)
Right-of-use asset		(639)		—
Property and equipment		(873)		(999)
Total deferred tax liabilities		(2,742)		(2,225)
Valuation allowance		51,812		50,086
Net deferred tax asset (liability)	$	—	$	—

Schedule of gross unrecognized tax benefits

	December 31,
	2019		2018
	(in thousands)
Beginning Balance	$	3,956	$	7,261
Increase resulting from current period tax positions		6,872		5,458
Decrease resulting from current period tax positions		(2,182)		(8,763)
Ending Balance	$	8,646	$	3,956

Schedule of reconciliation of Federal statutory tax rate

	Year Ended
	December 31,
	2019		2018
U.S. Statutory Tax Rate	21	%	21	%
Change in Valuation Allowance	(10.2)	%	(21.5)	%
State Tax Expense, net	0.9	%	1.8	%
Research and Development Tax Credit	0.9	%	0.5	%
Uncertain Tax Position - Research and Development Tax Credit	(3.4)	%	0	%
Permanent Difference - Interest Expense	(7.8)	%	0	%
Provision to Return, Other Permanent Differences and Other Adjustments	(1.4)	%	(1.8)	%
Income Tax Expense (Benefit)	0	%	0	%