Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Accounts Payable And Accrued Liabilities Current [Abstract]
Accrued license fees	$ 1,567,368	$ 817,578
Accrued payroll and payroll taxes	1,302,728
Accrued contract manufacturing	1,079,314	218,108
Accrued contract research	128,678	99,140
Accrued miscellaneous expenses	119,861	73,348
Accrued legal	111,543	174,592
Accrued audit and tax	102,000	111,250
Accrued pre-commercial costs	85,000	341,159
Accrued consulting	49,940	102,156
Total accrued expenses	$ 4,546,432	$ 1,937,331