Operating Expenses
Selling, general and administrative
Selling, general and administrative expenses for the three months ended March 31, 2021 were $3,881,717, composed of $1,734,333 of selling, general and administrative expenses of our Prescription Medicines segment, $546,995 of selling, general and administrative expenses of our Medical Devices segment and $1,600,389 of general corporate expenses.
Selling, general and administrative expenses for the three months ended March 31, 2020 were $4,816,463, composed of $3,130,414 of selling, general and administrative expenses of our Prescription Medicines segment, $743,813 of selling, general and administrative expenses of our Medical Devices segment and $942,236 of general corporate expenses.
Selling, general and administrative expenses for both segments include selling, marketing and regulatory expenses. Unallocated general corporate expenses include costs that were not specific to a particular segment but are general to the group, including expenses incurred for administrative and accounting staff, general liability and other insurance, professional fees and other similar corporate expenses.
Selling, general and administrative expenses decreased by $934,746, or 19%, during the three months ended March 31, 2021 compared to the same period of 2020. Decreased selling, general and administrative expenses were primarily driven by lower payroll expenses and direct marketing expenses as management sought to reduce expenses due to COVID-19; partially offset by increased accounting and legal fees and other expenses associated with the Merger.
Research and development
Research and development expenses for the three months ended March 31, 2021 were $19,181, in our Prescription Medicines segment. Research and development expenses for Prescription Medicines segment are composed entirely of consulting fees.
Research and development expenses for the three months ended March 31, 2020 were $139,385, in our Prescription Medicines segment. Research and development expenses for Prescription Medicines segment are composed of $100,000 for upfront licensing fees, $26,732 of consulting fees, and $12,653 of legal fees.
Research and development expenses decreased by $120,204 or 86% during the three months ended March 31, 2021 compared to the same period of 2020. Decreased research and development expenses were primarily driven by $100,000 of upfront licensing fees for the three months ended March 31, 2020 that did not reoccur during the three months ended March 31, 2021.
Depreciation and amortization
Depreciation and amortization expenses for the three months ended March 31, 2021 were $1,728,829, composed of $1,398,270 of depreciation and amortization expenses of our Prescription Medicines segment and $330,559 of depreciation and amortization expenses of our Medical Devices segment.
Depreciation and amortization expenses for the three months ended March 31, 2020 were $1,661,362, composed of $1,353,591 of depreciation and amortization expenses of our Prescription Medicines segment and $307,771 of depreciation and amortization expenses of our Medical Devices segment.
Prescription Medicines depreciation and amortization consists primarily of the amortization of the intangible assets related to Stendra® over its estimated useful life of 10 years. Medical Devices depreciation and amortization primarily consists of the amortization of the intangible assets related to Timm Medical and PTV over their estimated useful life of 12 years. The increase in amortization expense was primarily driven by the accelerated method of amortization related to the Stendra® product.