As of October 1, 2017, the Company completed a royalty purchase agreement with HealthCare Royalty Partners, or HCRP. In exchange for the payment of $40 million to the Company, HCRP obtained the right to receive Fampyra royalties payable by Biogen under the Biogen Collaboration Agreement up to an agreed upon threshold of royalties. When this threshold is met, which we believe may occur in mid-2022, the Fampyra royalty revenue will revert back to the Company and the Company will continue to receive the Fampyra royalty revenue from Biogen until the revenue stream ends. The Royalty Agreement does not include potential future milestones to be paid by Biogen.

Since the Company maintained rights under the Biogen Collaboration Agreement, therefore, the Royalty Agreement has been accounted for as a liability that will be amortized using the effective interest method over the life of the arrangement, in accordance with the relevant accounting guidance. The Company recorded the receipt of the $40 million payment from HCRP and established a corresponding liability in the amount of $40 million, net of transaction costs of approximately $2.2 million. The net liability is classified between the current and non-current portion of liability related to sale of future royalties in the consolidated balance sheets based on the recognition of the interest and principal payments to be received by HCRP in the next 12 months from the financial statement reporting date. The total net royalties to be paid, less the net proceeds received will be recorded to interest expense using the effective interest method over the life of the Royalty Agreement. The Company will estimate the payments to be made to HCRP over the term of the Royalty Agreement based on forecasted royalties and will calculate the interest rate required to discount such payments back to the liability balance. Over the course of the Royalty Agreement, the actual interest rate will be affected by the amount and timing of net royalty revenue recognized and changes in forecasted revenue. On a quarterly basis, the Company will reassess the effective interest rate and adjust the rate prospectively as necessary.

The following table shows the activity within the liability account for the years ended December 31, 2021 and December 2020.

(In thousands)	December 31, 2021			December 31, 2020
Liability related to sale of future royalties - beginning balance	$	15,257		$	24,401
Deferred transaction costs amortized		234			401
Non-cash royalty revenue payable to HCRP		(12,106	)		(11,486	)
Non-cash interest expense recognized		1,075			1,941
Liability related to sale of future royalties - ending balance	$	4,460		$	15,257

The interest and debt discount amortization expense is reflected as interest and amortization of debt discount expense in the Statement of Operations.