Debt	12 Months Ended
Dec. 31, 2019
Debt
Debt	7. Debt (in thousands, except share and per share data) In February 2018, the Company received a total of $500 from the issuance by Private NeuroBo of convertible promissory notes (the "Convertible Notes")with an original maturity date of December 31, 2022. Upon the effective date of the Merger, the Convertible Notes were converted into 1,565,300 shares of common stock. Prior to conversion, the lenders had the option to convert all of the then-unpaid note balance including principal and accrued but unpaid interest into common stock, at a conversion price of $0.40 per share after the earlier of (A) the closing of a firmly underwritten public offering pursuant to an effective registration statement under the Securities Act of 1933, as amended, covering the offer and sale of common stock for the account of the Company in the United States of America or similar registration in the Republic of Korea, or (B) January 1, 2020. On October 23, 2019, the Convertible Notes were amended (the “Amended Convertible Notes”) to require mandatory conversion upon the completion of a reverse merger transaction based on the then-unpaid note balance including principal and accrued but unpaid interest into common stock, at a conversion price of $0.40 per share. The amendment was accounted for as an extinguishment of the Convertible Notes. As a result of the extinguishment, the Amended Convertible Notes were recorded at their fair value in the amount of $11.2 million, the underlying beneficial conversion feature was reacquired at its intrinsic value of $9.8 million and the remaining debt discount of $0.3 million was reversed. Considering that the Amended Convertible Notes were issued at a substantial premium, the difference between the fair value of the Amended Convertible Notes and principal amount of the Convertible Notes was recorded as a credit to additional paid in capital in the amount of $10.6 million. Consequently, the Company recorded a loss on the extinguishment in the amount of $1.1 million which was reflected in the consolidated statements of operations and comprehensive loss. The Convertible Notes and Amended Convertible Notes (herein collectively referred to as the “Notes”) accrued interest at a rate of 5.00% per annum. The Company recorded interest on principal of $25 and $23 for the years ended December 31, 2019 and 2018, respectively. The fair value of the common stock, as determined using an option pricing model consistent with the AICPA Practice Guide, was in excess of the conversion price of the Convertible Notes. Accordingly, the Company initially recorded a $401 beneficial conversion feature upon issuance based on the intrinsic value of the conversion feature, which resulted in a debt discount with a corresponding amount to additional paid in capital. Subsequent to the issuance of the Convertible Notes, an additional beneficial conversion feature related to paid-in-kind interest was recorded in the amount of $104. Debt discount amortization related to the beneficial conversion feature was being amortized over the life of the Convertible Notes using the effective interest method as additional interest expense. Upon the conversion of the Convertible Notes into common stock on December 30, 2019, the remaining debt discount was written off to interest expense. The Company recorded interest expense of $104 and $18 for the years ended December 31, 2019 and 2018, respectively, related to the debt discount.

7. Debt (in thousands, except share and per share data)

In February 2018, the Company received a total of $500 from the issuance by Private NeuroBo of convertible promissory notes (the "Convertible Notes")with an original maturity date of December 31, 2022. Upon the effective date of the Merger, the Convertible Notes were converted into 1,565,300 shares of common stock.

Prior to conversion, the lenders had the option to convert all of the then-unpaid note balance including principal and accrued but unpaid interest into common stock, at a conversion price of $0.40 per share after the earlier of (A) the closing of a firmly underwritten public offering pursuant to an effective registration statement under the Securities Act of 1933, as amended, covering the offer and sale of common stock for the account of the Company in the United States of America or similar registration in the Republic of Korea, or (B) January 1, 2020. On October 23, 2019, the Convertible Notes were amended (the “Amended Convertible Notes”) to require mandatory conversion upon the completion of a reverse merger transaction based on the then-unpaid note balance including principal and accrued but unpaid interest into common stock, at a conversion price of $0.40 per share. The amendment was accounted for as an extinguishment of the Convertible Notes. As a result of the extinguishment, the Amended Convertible Notes were recorded at their fair value in the amount of $11.2 million, the underlying beneficial conversion feature was reacquired at its intrinsic value of $9.8 million and the remaining debt discount of $0.3 million was reversed. Considering that the Amended Convertible Notes were issued at a substantial premium, the difference between the fair value of the Amended Convertible Notes and principal amount of the Convertible Notes was recorded as a credit to additional paid in capital in the amount of $10.6 million. Consequently, the Company recorded a loss on the extinguishment in the amount of $1.1 million which was reflected in the consolidated statements of operations and comprehensive loss.

The Convertible Notes and Amended Convertible Notes (herein collectively referred to as the “Notes”) accrued interest at a rate of 5.00% per annum. The Company recorded interest on principal of $25 and $23 for the years ended December 31, 2019 and 2018, respectively.

The fair value of the common stock, as determined using an option pricing model consistent with the AICPA Practice Guide, was in excess of the conversion price of the Convertible Notes. Accordingly, the Company initially recorded a $401 beneficial conversion feature upon issuance based on the intrinsic value of the conversion feature, which resulted in a debt discount with a corresponding amount to additional paid in capital. Subsequent to the issuance of the Convertible Notes, an additional beneficial conversion feature related to paid-in-kind interest was recorded in the amount of $104.

Debt discount amortization related to the beneficial conversion feature was being amortized over the life of the Convertible Notes using the effective interest method as additional interest expense. Upon the conversion of the Convertible Notes into common stock on December 30, 2019, the remaining debt discount was written off to interest expense. The Company recorded interest expense of $104 and $18 for the years ended December 31, 2019 and 2018, respectively, related to the debt discount.