Cost of goods sold and gross margin
Cost of goods sold increased $1.0 million, or 30%, to $4.5 million for the nine months ended September 30, 2023, compared to the nine months ended September 30, 2022. This increase was primarily due to higher sales of Barostim.
Gross profit was $23.5 million for the nine months ended September 30, 2023, an increase of $11.7 million, or 99%, over the nine months ended September 30, 2022. Gross margin increased to 84% for the nine months ended September 30, 2023, compared to 77% for the nine months ended September 30, 2022. This increase was due primarily to a decrease in the cost per unit driven by an increase in the production volume.
Research and development expenses
R&D expenses increased $2.5 million, or 36%, to $9.4 million for the nine months ended September 30, 2023, compared to the nine months ended September 30, 2022. This change was driven by a $1.4 million increase in compensation expenses as a result of increased headcount, a $0.6 million increase in non-cash stock-based compensation expense and a $0.4 million increase in consulting fees.
Selling, general and administrative expenses
SG&A expenses increased $11.6 million, or 32%, to $47.5 million for the nine months ended September 30, 2023, compared to the nine months ended September 30, 2022. This change was primarily driven by a $6.9 million increase in compensation expenses, mainly as a result of increased headcount, a $1.6 million increase in marketing and advertising expenses associated with the commercialization of Barostim in the U.S, a $1.3 million increase in travel expenses, a $1.3 million increase in non-cash stock-based compensation expense and a $0.6 million increase in consulting fees.
Interest expense
Interest expense increased $1.2 million for the nine months ended September 30, 2023, compared to the nine months ended September 30, 2022. This increase was driven by the interest expense on borrowings under the Loan Agreement entered into on October 31, 2022.
Other income, net
Other income, net increased $2.5 million for the nine months ended September 30, 2023, compared to the nine months ended September 30, 2022. This increase was primarily driven by higher interest rates on interest-bearing accounts partially offset by a lower cash balance.
Provision for income taxes
Provision for income taxes was nominal for each of the nine months ended September 30, 2023 and September 30, 2022.
Liquidity, capital resources and plan of operations
We have incurred significant operating losses and negative cash flows from operations since our inception, and we anticipate that we will incur significant losses for at least the next several years. As of September 30, 2023 and December 31, 2022, we had cash and cash equivalents of $83.0 million and $106.2 million, respectively. For the three months ended September 30, 2023 and 2022, our net losses were $9.0 million and $9.8 million, respectively. For the nine months ended September 30, 2023 and 2022, our net losses were $32.0 million and $30.9 million, respectively. Our net cash used in operating activities for the nine months ended September 30, 2023 and 2022 was $31.2 million and $31.8 million, respectively.