Accrued Expenses - Schedule of Accrued Expenses (Detail) (USD $)	Sep. 30, 2013	Sep. 30, 2012
Accrued Liabilities Current [Abstract]
Accrued royalties, rebates, chargebacks, and distribution fees	$ 5,525,103	$ 2,851,140
Accrued research and development expenses	2,146,210	1,222,140
Accrued selling, general and administrative expenses	3,892,395	2,170,142
Other current liabilities	344,862	818,737
Total accrued expenses	$ 11,908,570	$ 7,062,159