Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Accounts Payable And Accrued Liabilities Current [Abstract]
Accrued pre-commercial costs	$ 629,806	$ 85,000
Accrued contract manufacturing	580,000	1,079,314
Accrued consulting	761,944	49,940
Accrued contract research and regulatory consulting	338,000	128,678
Accrued accounting, audit, and tax fees	163,000	102,000
Accrued legal	130,000	111,543
Accrued miscellaneous expenses	103,947	119,861
Accrued license fees	51,335	1,567,368
Accrued payroll and payroll taxes	1,090	1,302,728
Total accrued expenses	$ 2,759,122	$ 4,546,432