ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Organization (Details) $ / shares in Units, $ in Thousands										12 Months Ended
	Dec. 15, 2022 USD ($)	May 31, 2022 USD ($)	Dec. 15, 2021 USD ($)	May 18, 2021	Feb. 12, 2021 USD ($) $ / shares shares	Feb. 09, 2021 USD ($) $ / shares shares	Jun. 03, 2020 USD ($)	Feb. 13, 2020 USD ($)	Jan. 10, 2020 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock offering, shares sold (in shares) | shares					8,750,000	5,650,000
Stock offering, purchase price (in dollars per share) | $ / shares					$ 3.92	$ 2.48
Stock offering, gross proceeds					$ 34,300	$ 14,000
Stock offering, net proceeds					$ 32,200	$ 13,100
Stock split conversion ratio				0.25
Total revenues										$ 111,014	$ 106,275
Product sales, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenues										109,420	92,090
Product sales, net | Revision of Prior Period, Reclassification, Adjustment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenues											1,400
Other revenue
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenues										$ (985)	1,408
Other revenue | Revision of Prior Period, Reclassification, Adjustment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenues											$ (1,400)
Disposal Group, Disposed of by Sale, Not Discontinued Operations | NUCYNTA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses								$ 375,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Gralise
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses							$ 38,800		$ 75,000
Consideration received									$ 130,300
Consideration receivable as percentage of net sales after closing									75.00%
Threshold for consideration receivable on net sales after closing									$ 70,000
Remaining consideration receivable balance							39,700
Remaining consideration receivable reduction							$ 900
Forecast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred cash payment due in May and December 2022	$ 10,000	$ 16,000
Otrexup
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total purchase price of assets acquired			$ 45,499
Deferred cash payment due in May and December 2022			$ 26,021
Otrexup | Forecast
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Deferred cash payment due in May and December 2022	$ 10,000	$ 16,000