| • | | Launched strategic partnerships with Vault Health and AssistRx to enhance the patient experience in February 2022 |
| • | | Initiated screening for the first patient in an investigator-initiated Phase 4 clinical trial of JATENZO for the treatment of hypogonadal men with chronic kidney disease (CKD) in March 2022; expect to announce results from the trial in the first half of 2023 |
| • | | Recently initiated process to explore strategic alternatives to maximize stockholder value |
Fourth Quarter and Full Year 2021 Financial Results Highlights
Fourth quarter 2021 net revenue increased 88.0% to $4.6 million from $2.4 million in the same period last year. For the year ended December 31, 2021, net revenue was $14.0 million, an increase of 119.1% from $6.4 million for 2020, in each case related to the growth in sales of JATENZO.
Gross margin was 71.7% for the fourth quarter of 2021, compared to 85.2% for the prior year period, and 80.5% for the year ended December 31, 2021, compared to a negative margin in the prior year. The gross margin was negatively impacted by the write-off of $0.7 million and $7.8 million for obsolete inventory in the years ended December 31, 2021 and 2020, respectively.
Fourth quarter 2021 operating expenses increased by 3.1% to $10.5 million from $10.2 million in the same period last year, primarily attributed to increases in general and administrative expenses associated with increased headcount and costs associated with financing activities and operating as a public company. For the year ended December 31, 2021, operating expenses increased by 13.6% to $51.0 million from $44.9 million for 2020, driven by increased headcount and professional fees associated with financing activities and operating as a public company.
Included in total operating expenses for fourth quarter 2021 was a decrease in sales and marketing expenses of 5.0% to $5.7 million from $6.0 million in the same period last year, primarily attributed to the timing of advertising and promotional spend associated with JATENZO. For the year ended December 31, 2021, sales and marketing expenses increased by 0.5% to $30.7 million from $30.5 million for 2020, primarily attributed to an increase in commercial analytics and market research costs, and sales and marketing expenses associated with JATENZO.
Also included in total operating expenses for fourth quarter 2021 was an increase in general and administrative expenses by 18.2% to $4.3 million from $3.7 million in the same period last year, primarily attributed to an increase in personnel costs associated with a growing business and financing related costs. For the year ended December 31, 2021, general and administrative expenses increased by 39.6% to $16.7 million from $11.9 million for 2020, primarily attributed to higher personnel costs due to an increase in headcount and consulting costs, and an increase in public company costs.
Total operating expenses for fourth quarter 2021 also reflect a decrease in research and development expenses, which decreased by 8.8% to $0.5 million from $0.6 million in the same period last year, primarily attributed to ongoing clinical costs associated with our lead commercial asset. For the year ended December 31, 2021, research and development expenses increased by 51.4% to $3.6 million from $2.4 million for 2020, primarily attributed to clinical costs associated with our lead commercial asset, JATENZO, and licensing fees related to the HavaH and McGill agreements.