2019 vs. 2018
Consolidated net product sales were $523,616 in 2019 compared to $515,251 in 2018, an increase of $8,365 or 1.6%. Fourth quarter 2019 net product sales were $134,663 compared to $127,264 in fourth quarter 2018, an increase of $7,399 or 5.8%. Successful marketing and sales programs contributed to the increases in sales for both fourth quarter and twelve months 2019 compared to the corresponding periods in the prior year. Fourth quarter 2019 sales also benefited from the timing of sales between the third and fourth quarters of 2019, however, foreign currency translation had some adverse effects on consolidated sales for the twelve months 2019 period compared to 2018.
Product cost of goods sold were $329,102 in 2019 compared to $329,880 in 2018, a decrease of $778 or 0.2%. Product cost of goods sold includes $408 and $(39) in certain deferred compensation expenses (credits) in 2019 and 2018, respectively. These deferred compensation expenses principally result from changes in the market value of investments and investment income from trading securities relating to compensation deferred in previous years and are not reflective of current operating results. Adjusting for the aforementioned, product cost of goods sold decreased from $329,919 in 2018 to $328,694 in 2019, a decrease of $1,225 or 0.4%. As a percent of net product sales, these adjusted costs decreased from 64.0% in 2018 to 62.8% in 2019, a 1.3 favorable percentage point change.
Product cost of goods sold and resulting gross profit margins in 2019 benefited from increased sales and higher price realization which allowed the Company to recover some margin decline resulting from increases in certain input costs in recent years. Plant efficiencies driven by capital investments and ongoing cost containment programs contributed to the above discussed decreases in adjusted cost of goods sold as a percentage of sales in 2019. The prior year 2018 gross margin was adversely affected by the implementation and start-up of new manufacturing packaging lines and resulting operational inefficiencies, as well as unfavorable experience from self-insurance programs.
Selling, marketing and administrative expenses were $127,802 in 2019 compared to $117,691 in 2018, an increase of $10,111 or 8.6%. Selling, marketing and administrative expenses include $10,884 and $(1,064) in certain deferred compensation expenses (credits) in 2019 and 2018, respectively. These deferred compensation expenses principally result from changes in the market value of investments and investment income from trading securities relating to compensation deferred in previous years and are not reflective of current operating results. Adjusting for the aforementioned, selling, marketing and administrative expenses decreased from $118,755 in 2018 to $116,918 in 2019, a decrease of $1,837 or 1.5%. As a percent of net product sales, these adjusted expenses decreased from 23.0% of net product sales in 2018 to 22.3% of net product sales in 2019, a 0.7 favorable percentage point change. Higher price realization, lower general and administrative expenses, primarily legal and professional fees, and lower freight and delivery unit costs were the principal drivers in these favorable reductions, including reductions as a percentage of sales, in 2019.
Selling, marketing and administrative expenses include freight, delivery and warehousing expenses. These expenses decreased from $49,527 in 2018 to $49,288 in 2019, a decrease of $239 or 0.5%. As a percent of net product sales, these adjusted expenses decreased from 9.6% in 2018 to 9.4% in 2019, a 0.2 favorable percentage point change. During 2019, the Company implemented additional freight and delivery computer systems and carrier selection processes, including enhanced competitive bidding, which facilitated this favorable unit cost reduction in 2019.
Earnings from operations were $69,214 in 2019 compared to $70,482 in 2018, a decrease of $1,268. Earnings from operations include $11,292 and $(1,103) in certain deferred compensation expense (credits) in 2019 and 2018, respectively, which are discussed above. Adjusting for these deferred compensation expenses, adjusted earnings from operations increased from $69,379 in 2018 to $80,506 in 2019, an increase of $11,127 or 16.0%. Increased sales and higher price realization in 2019, as well as reductions in certain costs and expenses discussed above, contributed to these improved results.
Management believes the comparisons presented in the preceding paragraphs, after adjusting for changes in deferred compensation, are more reflective of the underlying operations of the Company.
Other income, net was $16,190 in 2019 compared to $2,724 in 2018, an increase of $13,466. Other income, net principally reflects $11,292 and $(1,103) of aggregate net gains (losses) and investment income on trading securities in 2019 and