NOTE 8—IDENTIFIABLE INTANGIBLE ASSETS:

Identifiable intangible assets consisted of the following:


	Gross carrying amount net of impairment				Accumulated amortization				Net carrying amount
	December 31,
	2018		2017		2018		2017		2018		2017
	(U.S. $ in millions)
Product rights	$	20,361	$	21,011	$	9,565	$	8,276	$	10,796	$	12,735
Trade names		606		617		91		55		515		562
In-process research and development (IPR&D)		2,694		4,343		—		—		2,694		4,343

Total	$	23,661	$	25,971	$	9,656	$	8,331	$	14,005	$	17,640

Product rights and trade names

Product rights and trade names are assets presented at amortized cost. Product rights and trade names represent a portfolio of pharmaceutical products from various categories with a weighted average life of approximately 12 years. Amortization of intangible assets amounted to $1,166 million, $1,444 million and $993 million in the years ended December 31, 2018, 2017 and 2016, respectively.

As of December 31, 2018, the estimated aggregate amortization of intangible assets for the years 2019 to 2023 is as follows: 2019—$1,034 million; 2020—$1,019 million; 2021—$889 million; 2022—$930 million and 2023—$896 million. These estimates do not include the impact of IPR&D that is expected to be successfully completed and reclassified to product rights.

IPR&D

Teva’s IPR&D are assets that have not yet been approved in major markets. Teva’s IPR&D is comprised mainly of the following acquisitions and related assets: various generic products (Actavis Generics)—$2,433 million; various generic products (Rimsa) —$50 million and Austedo —$211 million. IPR&D carry intrinsic risks that the asset might not succeed in advanced phases and may be impaired in future periods.

In 2018, Teva reclassified approximately $723 million relating to certain products from IPR&D to product rights following regulatory approval, mainly $444 million in connection with AJOVY and $103 million in connection with mesalamine and various other generic products.

Intangible assets impairment

Impairment of identifiable intangible assets amounted to $1,991 million, $3,238 million and $589 million in the years ended December 31, 2018, 2017 and 2016, respectively, and are recorded in earnings under intangible assets impairment.

Impairments of long-lived intangible assets in 2018 were $1,991 million, mainly consisting of:

Identifiable product rights of $1,068 million, mainly due to: (a) $412 million in connection with updated market assumptions regarding price and volume of products acquired from Actavis Generics currently marketed in the United States and supply constraints; (b) $290 million in certain international markets, due to a loss of several tenders and termination of products manufacturing lines; and (c) $222 million in Japan in connection with ongoing regulatory pricing reductions and generic competition.

IPR&D assets of $923 million, mainly related to revaluation of generic products acquired from Actavis Generics due to development progress and changes in other key valuation indications (e.g., market size, legal landscape, launch date or discount rate).