INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2017

INTANGIBLE ASSETS.

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

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

	December 31, 2017							December 31, 2016
	Remaining	Gross						Gross
	Useful Life	Carrying		Accumulated		Net Book		Carrying		Accumulated		Net Book
Product rights	(In years)	Amount		Amortization		Value		Amount		Amortization		Value
NUCYNTA	8.0	$	1,019,978	$	(266,590)	$	753,388	$	1,019,978	$	(172,288)	$	847,690
CAMBIA	6.0		51,360		(20,755)		30,605		51,360		(15,619)		35,741
Lazanda	—		—		—		—		10,480		(3,979)		6,501
Zipsor	4.3		27,250		(17,370)		9,880		27,250		(15,033)		12,217
		$	1,098,588	$	(304,715)	$	793,873	$	1,109,068	$	(206,919)	$	902,149

Summary of the future amortization expenses of intangible assets

Based on finite-lived intangible assets recorded as of December 31, 2017, and assuming the underlying assets will not be impaired and that we will not change the expected lives of the assets, future amortization expenses were estimated as follows (in thousands):

	Estimated
	Amortization
Year Ending December 31,	Expense
2018	$	101,774
2019		101,774
2020		101,774
2021		101,774
2022		99,969
Thereafter		286,808
Total	$	793,873