Revenues. Revenue, net increased by $9.1 million or 132% from $6.9 million for the nine months ended September 30, 2022 to $16.0 million for the nine months ended September 30, 2023. Unit sales increased by 108,198 units, or 151%, from 71,442 units for the nine months ended September 30, 2022, to 179,640 units for the nine months ended September 30, 2023. The decrease in the percentage of growth between dollars and units pertains to increased price discounts offered to the non-retail sales channel. Revenue, net consists of sales of Twirla and reflects the shipment of Twirla to specialty distributors, net of estimates for applicable variable consideration, which consist primarily of wholesale distribution fees, prompt pay and other discounts, rebates, chargebacks, product returns, and co-pay assistance programs.
Cost of product revenues. Cost of product revenues increased by $1.6 million or 31% from $5.2 million for the nine months ended September 30, 2022 to $6.8 million for the nine months ended September 30, 2023, and consists of direct and indirect costs related to the manufacturing of Twirla sold, including third-party manufacturing costs, packaging services, freight, and allocations of overhead costs that are primarily fixed such as salaries, benefits, and insurance.
Research and development expenses. Research and development expenses decreased by $0.7 million or 25% from $2.9 million for the nine months ended September 30, 2022 to $2.2 million for the nine months ended September 30, 2023. This decrease in research and development expenses was primarily due to a decrease in clinical development expenses of $0.8 million for the nine months ended September 30, 2023 as compared to the nine months ended September 30, 2022. This decrease reflects a reduction in spending related to our pipeline evaluation and development.
Selling and marketing expenses. Selling and marketing expenses decreased by $9.5 million, or 40%, from $23.5 million for the nine months ended September 30, 2022 to $14.0 million for the nine months ended September 30, 2023. This decrease in selling and marketing expenses is due to reduced spending on marketing initiatives and the optimization of our contract sales force.
General and administrative expenses. General and administrative expenses decreased by $1.0 million, or 10%, from $9.8 million for the nine months ended September 30, 2022 to $8.8 million for the nine months ended September 30, 2023. This decrease in general and administrative expense was primarily due to lower personnel-related costs due to lower headcount.
Loss on disposition of assets. In accordance with ASC 610-20, we recognized an $11.1 million, one-time, non-cash charge during the nine months ended September 30, 2022, which represented the loss on the transfer of fixed assets to Corium in connection with the amended Corium Agreement. There was no comparable expense during the nine months ended September 30, 2023.
Interest income. Interest income comprises interest earned on cash and cash equivalents.
Interest expense. Interest expense is attributable to our term loan with Perceptive and includes the amortization of the discount associated with allocating value to the common stock warrants issued to Perceptive and the amortization of the deferred financing costs associated with the term loan. Interest expense decreased by $1.6 million for the nine months ended September 30, 2023 compared to the nine months ended September 30, 2022 due to the reduction in the principal amount outstanding on the loan.
Unrealized gain on warrant liability. Unrealized gain on warrant liability reflects the non-cash changes in the estimated fair value of the warrant liability.
Benefit from income taxes. Benefit from income taxes represents $4.7 million received under the State of New Jersey’s Technology Business Tax Certificate Transfer Program sponsored by The New Jersey Economic Development Authority during the nine months ended September 30, 2022.
Liquidity and Capital Resources
At September 30, 2023, we had cash and cash equivalents totaling $2.9 million. We invest our cash equivalents in short-term highly liquid, interest-bearing investment-grade and government securities in order to preserve principal.