Intangible Assets

Intangible assets consisted of the following at December 31:



	2017			2016

Product and license rights	$	21,879,981		$	20,543,262
Less: accumulated amortization	(6,564,007		)	(4,988,333		)
Total product and license rights	15,315,974			15,554,929
Patents	9,177,647			8,844,994
Less: accumulated amortization	(3,158,990		)	(2,298,442		)
Total patents	6,018,657			6,546,552
Trademarks	118,934			61,715
Less: accumulated amortization	(9,020		)	(9,020		)
Total trademarks	109,914			52,695
Total intangible assets	$	21,444,545		$	22,154,176

During 2011, the Company acquired the Kristalose trademark and FDA registration from Mylan Inc. The agreement requires the Company to make future quarterly royalty payments over a seven-year period equal to a percentage of Kristalose net sales. The royalties are being treated as consideration for the assets acquired and are being capitalized and amortized over the remaining expected useful life of the acquired asset, currently through 2026. During 2017 and 2016, the Company incurred royalty obligations to Mylan Inc. of $1.0 million and $1.4 million, respectively.

During 2013, the Company entered into an agreement with Pernix to distribute and promote the branded prescription product Omeclamox-Pak. The $4.0 million upfront payment the Company paid to Pernix on October 29, 2013 (discussed more fully in Note 3) is included in product and license rights and is being amortized through June 2032, the remaining expected useful life of the acquired asset.

During 2014, the Company acquired the rights of the branded prescription product Vaprisol from Astellas. The intangible asset value is $3.0 million and is included in product and license rights. The asset is being amortized through February 2022, the remaining expected useful life of the acquired asset, which coincides with the life of the primary intellectual property asset.

In November 2016, the Company acquired the U.S. rights to Nordic Group B.V.’s injectable methotrexate product line. The agreement requires the Company to make future milestone payments over a fifteen-year period from the effective grant of the Regulatory Approval of the Methotrexate Pre-Filled Syringe Product in the U.S. The payments are being treated as consideration for the assets acquired and are being capitalized and will be amortized over the expected useful life of the acquired asset, once approval is granted. During 2016, the Company paid a deposit of $100,000 as well as recorded a liability provided through 180,000 unvested restricted shares of Cumberland stock, that will fully vest upon the FDA approval of the first Nordic product. As of December 31, 2017, the 180,000 shares of unvested restricted Cumberland stock are valued at $1.3 million.

During 2017 and 2016, the Company recorded an additional $0.4 million and $0.6 million, respectively, in intangible assets for patents, trademarks and capitalized patent costs, including amounts incurred in the protection of the Company's intellectual property. These costs will be amortized over the remaining expected useful life of the associated patents.

Amortization expense related to product and license rights, trademarks and patents were as follows for the years ended December 31:



	2017		2016		2015

Amortization expense	$	2,436,222	$	2,194,039	$	1,989,264

The expected amortization expense for the Company's current balance of intangible assets are as follows:



Year ending December 31:
2018	$	2,519,024
2019	2,542,770
2020	2,614,010
2021	2,465,544
2022 and thereafter	11,303,197
	$	21,444,545