Note 8. Intangible assets

Major components of intangible assets, net at the indicated dates consist of the following:


	December 31,
	2019		2018
	(in thousands)
Proprietary modified-release drug delivery technology	$	15,600	$	15,600
Tussionex ANDA		4,829		4,829
CPI profit sharing		2,043		2,043
Patents		1,971		2,307
Other		1,035		1,035
		25,478		25,814
Accumulated amortization		(12,935)		(11,198)
	$	12,543	$	14,616

As part of the June 15, 2009 reorganization of the Company as Neos Therapeutics, Inc., the Company performed a purchase price allocation analysis. The proprietary modified-release drug delivery technology was valued at $15.6 million based on projected cash flows expected to be generated from this technology. The $15.6 million is being amortized on a straight-line basis over 20 years.

On August 28, 2014, the Company completed an acquisition of the rights to Tussionex ANDA from Cornerstone and Coating Place, Inc. ("CPI") which was accounted for as an asset acquisition. Prior to the acquisition, the Company, Cornerstone and CPI shared profits generated by the sale and manufacture of the product under a development and manufacturing agreement, and Cornerstone had commercialization rights to the product. The Company paid $4.2 million to Cornerstone to buy out their rights to commercialize and derive future profits from the product and entered into an agreement whereby Cornerstone transferred certain assets associated with the product to the Company. Legal fees of $90,000 associated with this buyout agreement have been capitalized as part of the purchase price. Additional estimated earnout costs due to Cornerstone of $589,000, recorded at fair value by the Company based upon a valuation provided by a third-party valuation firm, were capitalized as part of the purchase price of this intangible asset. This earnout amount was revalued at December 31, 2019, 2018 and 2017, resulting in a $7,000, $133,000 and $62,000 decrease in the estimated fair value of the earnout, respectively, which is recorded in other income (expense), net in the Company’s consolidated statements of operations. In addition, the Company paid $2.0 million to CPI to buy out their rights to future profits from the collaboration and entered into an agreement whereby CPI will continue to supply a component of the product. Legal fees of $43,000 associated with this buyout agreement have been capitalized as part of the purchase price of this intangible asset. These two intangible assets have an expected life of ten years and are being amortized on a straight-line basis beginning September 2014.

Patents utilized in the manufacturing of the Company’s generic Tussionex product which total $352,000 are being amortized over their expected useful life of 10 years. Patents utilized in the manufacturing of Adzenys XR-ODT which total $599,000 are being amortized over their expected useful life, including $535,000 being amortized for approximately 16 years beginning with the approval of Adzenys XR-ODT on January 27, 2016 and $64,000 being amortized for approximately 15 years beginning in December 2017. Patents utilized in the manufacturing of Cotempla XR-ODT which total $83,000 are being amortized over their expected useful life of approximately 15 years, beginning with the approval of Cotempla XR-ODT on June 19, 2017. Patents utilized in the manufacturing of Adzenys ER which total $451,000 are being amortized over their expected useful life of approximately 15 years, beginning with the approval of Adzenys ER on September 15, 2017. Patent filing costs capitalized, for which the Company estimated to have future value, were $486,000 as at December 31, 2019. Once the patent is approved and commercial revenue realized, the costs associated with the patent are amortized over the useful life of the patent.

Total amortization expense for intangible assets was $1,737,000, $1,737,000 and 1,660,000 for the years ended December 31, 2019, 2018 and 2017, respectively. In addition, during the year ended December 31, 2019, the Company wrote-off $395,000 of capitalized patent filing costs.

Aggregate amortization of intangible assets for each of the next five years and thereafter is as follows:


Year ending	December 31,
	(in thousands)
2020	$	1,737
2021		1,737
2022		1,737
2023		1,642
2024		1,333
Thereafter		3,871
	$	12,057