Subsequent Events	12 Months Ended
Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On January 3, 2019 and January 15, 2019, the Company granted options to employees to purchase in aggregate 76,500 and 13,200 shares of the Company’s Common Stock at an exercise price of $13.61 and $14.62 per share, respectively, which represents the per share closing price of the Company’s Common Stock on the dates of grant. These options were issued under the 2017 Plan and have a ten year term. The options vest as follows: 1/48th of the option shares vest every month on the anniversary of the grant date. From January 1, 2019 through March 15, 2019, the Company issued a total of 80,000 shares of Common Stock in connection with stock option exercises. As a result of the stock option exercises, the Company received aggregate proceeds of $601,250. On February 21, 2019, the Company announced that its Phase 2 clinical trial evaluating OPNT001, a naloxone nasal spray for the treatment of bulimia nervosa did not meet the primary endpoint of reducing the number of binging days from baseline to week eight. Key secondary endpoints were also not met. Based on these results, the Company will not devote additional resources to the development of OPNT001. On March 18, 2019, the Company and Adapt entered into Amendment No. 2 to the License Agreement. Amendment No. 2 sets forth the timing and amounts that Adapt is allowed to deduct going forward from royalties and milestones payable to the Company and SWK in relation to payments that Adapt has paid or will pay under a license agreement with a Third Party (as defined in the License Agreement), as further discussed in Note 9. Licensee Fee Payable. As provided in Amendment No. 2, going forward Adapt may only deduct a maximum of $9.0 million from royalties and milestones payable to the Company and SWK under the License Agreement in regards to the Third Party license agreement entered into by Adapt on or around February 28, 2018. Under Amendment No. 2, with respect to $6.5 million of the $9 million, Adapt may only deduct a maximum of $2.0 million in any one calendar quarter from the royalties payable to the Company under the License Agreement and SWK under the SWK Purchase Agreement. As provided in the License Agreement, if Net Narcan Sales (as defined in the License Agreement) exceeds $200 million in any calendar year, the Company and SWK will be due a milestone of $15.0 million. Under Amendment No. 2, if this $15.0 million milestone becomes payable to the Company and SWK, Adapt may deduct $2.5 million from this $15.0 million milestone, along with any outstanding balance of the $6.5 million that has not already been deducted in previous quarters. Amendment No. 2 also amended Section 5.5 of the License Agreement to provide that Adapt may still enter into Third Party licensing arrangements; however, in order to exercise its right to deduct any payments with respect thereto, with certain specified exceptions, after March 18, 2019, Adapt will need the consent of the Company that the licensing arrangement is acceptable under the provisions of Amendment No. 2 (in particular the amended Section 5.5 set forth therein). In all instances, any Third Party licensing arrangement and associated deductions taken by Adapt must comply with the provisions of Section 5.5 as amended by Amendment No. 2.

Subsequent Events

On January 3, 2019 and January 15, 2019, the Company granted options to employees to purchase in aggregate 76,500 and 13,200 shares of the Company’s Common Stock at an exercise price of $13.61 and $14.62 per share, respectively, which represents the per share closing price of the Company’s Common Stock on the dates of grant. These options were issued under the 2017 Plan and have a ten year term. The options vest as follows: 1/48th of the option shares vest every month on the anniversary of the grant date.

From January 1, 2019 through March 15, 2019, the Company issued a total of 80,000 shares of Common Stock in connection with stock option exercises. As a result of the stock option exercises, the Company received aggregate proceeds of $601,250.

On February 21, 2019, the Company announced that its Phase 2 clinical trial evaluating OPNT001, a naloxone nasal spray for the treatment of bulimia nervosa did not meet the primary endpoint of reducing the number of binging days from baseline to week eight. Key secondary endpoints were also not met. Based on these results, the Company will not devote additional resources to the development of OPNT001.

On March 18, 2019, the Company and Adapt entered into Amendment No. 2 to the License Agreement. Amendment No. 2 sets forth the timing and amounts that Adapt is allowed to deduct going forward from royalties and milestones payable to the Company and SWK in relation to payments that Adapt has paid or will pay under a license agreement with a Third Party (as defined in the License Agreement), as further discussed in Note 9. Licensee Fee Payable. As provided in Amendment No. 2, going forward Adapt may only deduct a maximum of $9.0 million from royalties and milestones payable to the Company and SWK under the License Agreement in regards to the Third Party license agreement entered into by Adapt on or around February 28, 2018. Under Amendment No. 2, with respect to $6.5 million of the $9 million, Adapt may only deduct a maximum of $2.0 million in any one calendar quarter from the royalties payable to the Company under the License Agreement and SWK under the SWK Purchase Agreement. As provided in the License Agreement, if Net Narcan Sales (as defined in the License Agreement) exceeds $200 million in any calendar year, the Company and SWK will be due a milestone of $15.0 million. Under Amendment No. 2, if this $15.0 million milestone becomes payable to the Company and SWK, Adapt may deduct $2.5 million from this $15.0 million milestone, along with any outstanding balance of the $6.5 million that has not already been deducted in previous quarters.

Amendment No. 2 also amended Section 5.5 of the License Agreement to provide that Adapt may still enter into Third Party licensing arrangements; however, in order to exercise its right to deduct any payments with respect thereto, with certain specified exceptions, after March 18, 2019, Adapt will need the consent of the Company that the licensing arrangement is acceptable under the provisions of Amendment No. 2 (in particular the amended Section 5.5 set forth therein). In all instances, any Third Party licensing arrangement and associated deductions taken by Adapt must comply with the provisions of Section 5.5 as amended by Amendment No. 2.