AstraZeneca posted strong second-quarter results that slightly exceeded our expectations. However, we don't expect any changes to our fair value estimate based on the minor outperformance.
Sales increased operationally 1% year over year, as strong sales from cholesterol-lowering drug Crestor offset increased generic competition on several older drugs. Earnings per share increased 9% from the prior-year period, thanks to operating efficiencies and a lower tax rate. Given the strong first half, the company increased its full-year earnings per share estimate by 5% to $6.35-$6.65, which we expect it can easily achieve.
Workhorse Crestor continued to post strong gains in the quarter, offsetting generic competition to the company's older drugs. Crestor sales increased 23% from the prior-year period, greatly exceeding the overall growth in the market for statins (other cholesterol-lowering drugs). We believe the new indication targeting C-reactive protein along with strong support in emerging markets is driving the drug's growth. We expect healthy double-digit growth for Crestor over the next three years. This strong growth helped offset generic competition to cardiovascular drug Toprol-XL, respiratory drug Pulmicort, and cancer drugs Arimidex and Casodex.
Operating expenses fell as a percentage of total sales by almost 300 basis points versus the year-ago period. Most of the decline came from research and development, which is somewhat worrisome as new products are the driver of long-term growth. However, cost of goods sold also fell largely because of operating efficiencies. While we continue to expect improvement in gross margins, we believe expenses in research and development will probably reverse and increase over the next several years.
We believe the Food and Drug Administration panel's 7 to 1 vote supporting approval of AstraZeneca's new drug Brilinta for cardiovascular disease bodes well for final approval. Even though the very risk-sensitive FDA may delay final approval until late 2010, we expect the eventual approval of the drug, given strong clinical support. Further, the drug's superior efficacy versus market leader Plavix should translate into blockbuster potential for Brilinta.