Note 8 - Derivative Warrant Liability (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

	Issuance Date	Expiration Date	Exercise Price as of December 31, 2018		Shares Underlying Warrants on Issuance Date		Shares Issued upon Warrant Exercises as of December 31, 2018		Shares Underlying Warrants Outstanding as of December 31, 2018 (1)
2014 Warrants	08/05/2014	08/05/2019	$	65.50		2,500		1,526		974
Series A Warrants	02/03/2015	02/03/2020	$	3.80		5,542		5,222		320
Series C Warrants	05/19/2015	05/19/2020	$	53.43		1,075		–		1,075
Series D Warrants	12/11/2015	12/11/2020	$	40.00		25,125		25,078		47
Series F Warrants	04/01/2016	04/01/2021	$	40.00		25,733		11,692		14,041
Series I Warrants	09/13/2016	09/13/2021	$	220.00		35,650		–		35,650
Series K Warrants	02/17/2017	2/17/2022	$	3.80		312,516		308,660		3,856
						408,141		352,178		55,963

Schedule of Warrant Exercises [Table Text Block]

	Twelve Months Ended December 31, 201 8
	Common Stock Issued		Proceeds
Series A Warrants		251		1,054
Series K Warrants		300,660		1,262,712
		300,911	$	1,263,766

- Definition

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

+ References + Details