Intangible Assets

Intangible assets consisted of the following at December 31:



	2015			2014

Product and license rights	$	18,011,362		$	16,477,749
Less: accumulated amortization	(3,541,305		)	(2,225,949		)
Total product and license rights	14,470,057			14,251,800
Patents	8,236,719			8,194,264
Less: accumulated amortization	(1,551,430		)	(877,523		)
Total patents	6,685,289			7,316,741
Trademarks	22,270			9,020
Less: accumulated amortization	(9,020		)	(9,020		)
Total trademarks	13,250			—
Total intangible assets	$	21,168,596		$	21,568,541

In February 2014, the Company acquired the rights of the branded prescription product Vaprisol from Astellas (discussed more fully in Note 3). The intangible asset value is $3.0 million and is included in product and license rights. The asset will be amortized through February 2022, the remaining expected useful life of the acquired asset, which coincides with the life of the primary intellectual property asset.

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 Therapeutics on October 29, 2013 (discussed more fully in Note 3) is included in product and license rights and will be amortized through June 2032, the remaining expected useful life of the acquired asset. The Company will continue to market and sell Omeclamox-Pak through its agreement with GEL and is now responsible for the supply chain, national accounts and all sales promotion.

In 2011, the Company acquired the Kristalose trademark and FDA registration from Mylan Inc. The agreement requires the Company to make future quarterly payments over a seven-year period equal to a percentage of Kristalose net sales. The payments 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 the remaining term of the 15 year agreement, through 2026. During 2015 and 2014, the Company paid $1.5 million and $1.3 million, respectively, to Mylan Inc. in Kristalose payments.

During 2015 and 2014 the Company recorded an additional $0.1 million and $3.3 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 was $2.0 million, $1.6 million and $0.9 million during 2015, 2014 and 2013, respectively. The expected amortization expense for the Company's current balance of intangible assets are as follows:



Year ending December 31:
2016	$	2,103,553
2017	2,103,553
2018	2,103,553
2019	2,103,553
2020 and thereafter	12,754,384
	$	21,168,596