INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Summary of the gross carrying amounts and net book values of our intangible assets

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

	December 31, 2018								December 31, 2017
Product rights	Remaining Useful Life (In years)	Gross Carrying Amount		Accumulated Amortization			Net Book Value		Gross Carrying Amount		Accumulated Amortization			Net Book Value
NUCYNTA	7.0	$	1,019,978	$	(360,891	)	$	659,087	$	1,019,978	$	(266,590	)	$	753,388
CAMBIA	5.0	51,360		(25,891		)	25,469		51,360		(20,755		)	30,605
Zipsor	3.3	27,250		(19,707		)	7,543		27,250		(17,370		)	9,880
		$	1,098,588	$	(406,489	)	$	692,099	$	1,098,588	$	(304,715	)	$	793,873

Summary of the future amortization expenses of intangible assets

Future amortization expenses were estimated as follows (in thousands):

Year Ending December 31,	Estimated Amortization Expense
2019	$	101,774
2020	101,774
2021	101,774
2022	99,969
2023	99,227
Thereafter	187,581
Total	$	692,099