INTANGIBLE ASSETS

3 Months Ended

Mar. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

INTANGIBLE ASSETS

INTANGIBLE ASSETS

The gross carrying amounts and net book values of intangible assets were as follows (in thousands): 

	March 31, 2020											December 31, 2019
Product rights	Remaining Useful Life (In years)	Gross Carrying Amount		Accumulated Amortization			Disposition			Net Book Value		Gross Carrying Amount		Accumulated Amortization			Impairment			Net Book Value
NUCYNTA	—	$	830,188	$	(461,119	)	$	(369,069	)	$	—	$	1,019,978	$	(455,192	)	$	(189,790	)	$	374,996
CAMBIA	3.7	51,360		(32,311		)	—			19,049		51,360		(31,027		)	—			20,333
Zipsor	2.0	27,250		(22,628		)	—			4,622		27,250		(22,044		)	—			5,206
Total		$	908,798	$	(516,058	)	$	(369,069	)	$	23,671	$	1,098,588	$	(508,263	)	$	(189,790	)	$	400,535

Amortization expense was $7.8 million and $25.4 million for the three months ended March 31, 2020 and 2019, respectively.

In February 2020, the Company divested its remaining rights, title and interest in and to the NUCYNTA franchise of products from the Company. As a result, the Company derecognized the remaining carrying value of $369.1 million of the NUCYNTA product rights.

Based on finite-lived intangible assets recorded as of March 31, 2020, and assuming the underlying assets will not be impaired and that the Company will not change the expected lives of the assets, future amortization expenses were estimated as follows (in thousands): 

Year Ending December 31,	Estimated Amortization Expense
2020 (remainder)	$	5,605
2021	7,473
2022	5,668
Thereafter	4,925
Total	$	23,671