Statements of Income (USD $)	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Revenue
Product sales	$ 25,512,028	$ 24,434,823	$ 25,151,822
Contract research and development	422,879	2,598,596	3,427,398
Total revenue	25,934,907	27,033,419	28,579,220
Cost of sales	5,720,277	7,025,181	9,325,511
Gross profit	20,214,630	20,008,238	19,253,709
Expenses
Selling, general , and administrative	2,235,475	2,240,563	2,380,603
Research and development	3,585,339	2,570,821	2,600,058
Total expenses	5,820,814	4,811,384	4,980,661
Income from operations	14,393,816	15,196,854	14,273,048
Interest income	2,122,133	2,359,603	2,350,191
Income before taxes	16,515,949	17,556,457	16,623,239
Provision for income taxes	5,380,074	5,727,619	5,242,144
Net income	$ 11,135,875	$ 11,828,838	$ 11,381,095
Net income per share - basic	$ 2.30	$ 2.44	$ 2.37
Net income per share - diluted	$ 2.29	$ 2.43	$ 2.34
Weighted average shares outstanding
Basic	4,851,460	4,839,810	4,796,227
Diluted	4,867,691	4,863,546	4,863,471