Note 13 - Income Taxes - Reconciliation of Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Federal tax benefit at statutory rate	(34.00%)	(34.00%)
State tax, net of Federal benefit	(16.30%)	(2.30%)
Change in fair value of warrant	(126.10%)
Change in tax rate	205.50%
Litigation settlement charge		4.60%
Acquisition costs		2.80%
Orphan drug credit	(36.00%)	(4.40%)
Change in valuation allowance	(38.80%)	27.20%
Stock compensation	1.20%	4.20%
Other	1.00%	(0.10%)
Total provision	(43.50%)	(2.00%)