different sales structure and the reallocation of resources, as announced on September 21, 2020, we are increasing the number of virtual interactions and educational events with physicians and ensuring that we have an overall larger presence in the healthcare community. We believe these measures will support our efforts to grow sales of Trogarzo® and EGRIFTA SV® in the U.S.
Cost of Sales
For the three- and nine-month periods ended August 31, 2020, cost of sales was $6,111,000 and $20,252,000 compared to $6,437,000 and $19,087,000 for the same periods ended August 31, 2019, or Fiscal 2019. Cost of goods sold was $4,611,000 and $15,780,000 in the three and nine-month periods of 2020 compared to $5,215,000 and $15,371,000 for the same periods in the previous year. The decrease in cost of goods sold was mainly due to lower sales of EGRIFTA® which was offset by a higher proportion of Trogarzo® sales. Cost of sales also included the amortization of the other asset of $1,220,000 and $3,661,000 for the three and nine-month periods ended August 31, 2020. In addition, cost of sales includes write-downs of $282,000 and $676,000 to recognize inventories at net realizable value for the three- and nine-month periods ended August 31, 2020, respectively ($nil and $3,000 for the corresponding periods in the prior year), which includes write-downs of $422,000 during the nine-month period ended August 31, 2020 on excess stock of EGRIFTA® mainly due to the Company’s decision to switch patients to and only actively commercialize EGRIFTA SV® in the U.S.
R&D Expenses
R&D expenses for the three- and nine-month periods ended August 31, 2020 amounted to $4,183,000 and $11,224,000 compared to $2,152,000 and $6,964,000 in the comparable periods of Fiscal 2019.
The increase was largely due to the development of our oncology platform, the F8 formulation and the multi-dose pen injector as well as regulatory expenses and increased medical education initiatives in Europe in preparation for the Trogarzo® launch.
Selling Expenses
Selling expenses increased to $7,025,000 and $20,327,000 for the three- and nine-month periods ended August 31, 2020 compared to $6,389,000 and $18,809,000 for the same periods last year.
The increase was mainly associated with increased activities in Europe.
The amortization of the intangible asset value for the EGRIFTA®, EGRIFTA SV® and Trogarzo® commercialization rights was also included in selling expenses. As such, we recorded an expense of $796,000 for the third quarter of Fiscal 2020 compared to $641,000 for the same quarter last year and $2,155,000 for the nine-month period ended August 31, 2020 and $1,770,000 for the same period last year.
General and Administrative Expenses
General and administrative expenses in the three- and nine-month periods ended August 31, 2020 amounted to $2,699,000 and $8,975,000 compared to $1,772,000 and $5,072,000 reported in the comparable periods of Fiscal 2019.
The increase in general and administrative expenses was mainly associated with business growth, increased activity in Europe, increased administrative expenses as a result of our
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