CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended				6 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Revenue:
Product revenue	$ 5,741,920		$ 4,415,786		$ 10,100,312		$ 8,684,598
Royalty and other revenue	2,889,458		2,891,192		6,184,791		5,632,252
Total revenue	8,631,378		7,306,978		16,285,103		14,316,850
Operating expenses:
Cost of product revenue	2,092,815	[1]	1,471,561	[1]	3,645,624	[1]	2,737,311	[1]
Cost of royalty and other revenue	418,419		376,991		834,289		748,733
Research and development	3,074,625	[1]	3,119,279	[1]	6,592,086	[1]	5,814,327	[1]
Selling, general and administrative	2,493,093	[1]	1,812,617	[1]	4,782,210	[1]	3,600,854	[1]
Total operating expenses	8,078,952		6,780,448		15,854,209		12,901,225
Income from operations	552,426		526,530		430,894		1,415,625
Investment income	52,247		96,679		118,183		195,637
Income before income taxes	604,673		623,209		549,077		1,611,262
Income tax provision
Net income	$ 604,673		$ 623,209		$ 549,077		$ 1,611,262
Earnings per share:
Basic	$ 0.02		$ 0.02		$ 0.02		$ 0.05
Diluted	$ 0.02		$ 0.02		$ 0.02		$ 0.05
Weighted average shares outstanding:
Basic	30,796,797		30,780,279		30,804,485		30,773,967
Diluted	30,933,832		30,920,400		30,969,233		30,922,474

[1] Includes non-cash stock-based compensation as follows: Cost of product revenue $ 8,709 $ 12,246 $ 23,745 $ 27,368 Research and development 60,713 51,926 133,069 112,747 Selling, general and administrative 175,176 177,957 369,800 364,897