Statements Of Income (USD $)	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Revenue
Product sales	$ 5,762,925	$ 5,394,758	$ 18,025,002	$ 17,975,331
Contract research and development	762,296	763,768	1,785,920	2,995,590
Total revenue	6,525,221	6,158,526	19,810,922	20,970,921
Cost of sales	1,738,618	2,174,878	5,147,884	7,048,396
Gross profit	4,786,603	3,983,648	14,663,038	13,922,525
Expenses
Selling, general , and administrative	570,741	520,044	1,714,545	1,742,721
Research and development	501,325	718,688	1,801,609	1,825,159
Total expenses	1,072,066	1,238,732	3,516,154	3,567,880
Income from operations	3,714,537	2,744,916	11,146,884	10,354,645
Interest income	600,395	591,694	1,784,963	1,754,586
Income before taxes	4,314,932	3,336,610	12,931,847	12,109,231
Provision for income taxes	1,415,590	1,047,519	4,211,964	3,825,819
Net income	$ 2,899,342	$ 2,289,091	$ 8,719,883	$ 8,283,412
Net income per share - basic	$ 0.60	$ 0.48	$ 1.80	$ 1.73
Net income per share - diluted	$ 0.60	$ 0.47	$ 1.80	$ 1.71
Weighted average shares outstanding
Basic	4,847,619	4,807,859	4,832,630	4,786,790
Diluted	4,872,019	4,873,429	4,856,851	4,852,360