Prepaid Expenses and Other Current Assets - Prepaid Expenses and Other Current Assets (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid research fees	$ 358,209	$ 388,977
Prepaid insurance	800,261	638,139
Prepaid pre-commercialization fees	17,030	65,000
Prepaid subscriptions fees	170,552	23,347
Prepaid rent	31,561
Other	272,168	58,281
Total prepaid expenses and other current assets	$ 1,649,781	$ 1,173,744