7. EQUITY COMPENSATION PLANS (Tables)

9 Months Ended

Jan. 31, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of stock option transaction activity

Stock Options	Shares			Weighted Average Exercisable Price
Outstanding, May 1, 2014		17,165,333		$1.58
Granted		4,336,296		$1.74
Exercised		(294,878	)	$0.95
Cancelled or expired		(527,357	)	$3.51
Outstanding, January 31, 2015		20,679,394		$1.57

Share-based compensation expense

	Three Months Ended January 31,				Nine Months Ended January 31,
	2015		2014		2015		2014
Cost of contract manufacturing	$	16,000	$	18,000	$	48,000	$	58,000
Research and development		685,000		769,000		2,288,000		2,231,000
Selling, general and administrative		915,000		814,000		2,944,000		2,625,000
Total	$	1,616,000	$	1,601,000	$	5,280,000	$	4,914,000

Share-based compensation from:
Stock options	$	1,561,000	$	1,540,000	$	5,086,000	$	4,549,000
Restricted stock awards		–		–		–		139,000
Employee stock purchase plan		55,000		61,000		194,000		226,000
	$	1,616,000	$	1,601,000	$	5,280,000	$	4,914,000