Note 7 - Accrued Expenses - Summary of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accrued clinical trial costs	$ 2,765	$ 2,570
Accrued consulting and service fee expenses	1,274	1,860
Accrued interest	1,205
Accrued payroll and related costs	1,069	2,400
Accrued legal and professional fees	713	1,022
Accrued contract manufacturing costs	500	666
Other	394	1,037
Accrued expenses	$ 7,920	$ 9,555