10. DEBT

The following table summarizes loans payable, net (in thousands):

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The outstanding loans payable as of the periods presented was related to our Credit Agreement with MidCap entered on September 27, 2019 (Closing Date) and amended on March 29, 2021 (First Amendment), February 11, 2022 (Second Amendment) and July 27, 2022 (Third Amendment). The Credit Agreement provides for a $60.0 million term loan credit facility. At the Closing Date, $10.0 million was funded (Tranche 1), in May 2020, an additional $10.0 million was funded (Tranche 2), at the Second Amendment, an additional $10.0 million was funded (Tranche 3), at the Third Amendment, an additional $10.0 million was funded (Tranche 4), and in March 2023, an additional $20.0 million was funded (Tranche 5). As of December 31, 2023, the outstanding principal balance of the loan was $60.0 million, and no remaining funds are available for draw under the term loan credit facility.

The First Amendment to the Credit Agreement extended the period through which Tranche 3 was available to us. The Second Amendment to the Credit Agreement, among other things, amended the applicable funding conditions, applicable commitments and certain other terms relating to available credit facilities (Tranches 3 and 4), added additional term loan credit facility (Tranche 5), and revised certain terms related to the financial covenants.

Following the Third Amendment, the maturity date for the term loans is on September 1, 2026, and the interest-only period is through October 1, 2024. The interest rate applicable to the term loans under the amended Credit Agreement is the sum of one-month Secured Overnight Financing Rate (SOFR), plus an adjustment of 0.11448%, subject to 1.50% applicable floor, plus applicable margin of 5.65%. A final payment fee of 2.5% of principal is due at maturity date of the term loans. Prior to the Third Amendment, the outstanding principal balance of the loan bore interest at an annual rate of one-month London Interbank Offered Rate (LIBOR), or a comparable applicable index rate determined pursuant to the Credit Agreement if the LIBOR was no longer available, plus applicable margin of 5.65%, subject to a LIBOR floor of 1.50% and was payable monthly in arrears.

We may make voluntary prepayments, in whole or in part, subject to certain prepayment premiums and additional interest payments. The Credit Agreement also contains certain provisions, such as event of default and change in control provisions, which, if triggered, would require us to make mandatory prepayments on the term loan, which are subject to certain prepayment premiums and additional interest payments. The obligations under the amended Credit Agreement are secured by a perfected security interest in all of our assets including our intellectual property.

The amendment to the Credit Agreement in 2022 was accounted for as debt modification. As such, fees paid to Midcap of $0.4 million were recorded as additional debt discount and added to the unamortized debt discount that are being amortized as interest expense through maturity using the effective interest rate method. Debt issuance costs are recorded as a direct deduction from the outstanding principal balance of the term loan.

Interest expense, including amortization of the debt discount and accretion of the final fees related to the Credit Agreement for the years ended December 31, 2023, 2022 and 2021 were $6.8 million, $3.0 million and $1.7 million, respectively. Accrued interest of $1.5 million and $0.8 million as of December 31, 2023 and 2022, respectively, was included within other accrued liabilities in the balance sheet.

The following table presents the future minimum principal payments of the outstanding loan as of December 31, 2023 (in thousands):

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The amended Credit Agreement contains certain covenants which, among others, require us to deliver financial reports at designated times of the year and maintain minimum unrestricted cash and trailing net revenues. As of December 31, 2023, we were not in violation of any covenants.