Pharmaceutical companies will suffer an estimated $65 billion drop in sales by 2019 due to the patent expirations of several leading drugs, and AstraZeneca will be one of the hardest hit, according to research and consulting firm GlobalData.

 Besides AstraZeneca, the company’s report states that the drug makers hit hardest will include Otsuka and Eli Lilly, with a significant proportion of losses coming in the central nervous system (CNS) treatment sector.

 Adam Dion, MS, GlobalData’s analyst covering Healthcare Industry Dynamics, said that Eli Lilly and AZ have seen profits fall in the CNS therapeutics market since 2010, with the latter losing the greatest share over the past three years.

 “AZ’s CNS segment has been bleeding sales as a result of the company losing its patent on Seroquel (quetiapine fumarate), a treatment for bipolar disorder, which led to the entry of cheaper generic alternatives from Teva and Sandoz,” according to Dion. GlobalData estimates AZ’s share to have been around 9 percent in 2010, which has now fallen to only 3 percent in 2013.

 “Eli Lilly’s market share declined from 14.3 percent in 2010 to 11.2 percent in 2013, primarily thanks to decreasing sales of Zyprexa (olanzapine), the company’s dopamine antagonist used to treat schizophrenia and bipolar disorder,” noted Dion. “Zyprexa sales have plummeted from over $5 billion to $1.2 billion over the same period, as a result of the drug losing its U.S. patent exclusivity in 2011.”

 The analyst added that while Otsuka’s anti-psychotic drug Abilify (aripiprazole), which the company co-markets with Bristol-Myers Squibb, was the sales leader in the CNS arena with $9.5 billion in 2013, the drug faces a less positive future.

 “Abilify’s upcoming U.S. patent expiration in 2015 means the drug will lose a massive $6.2 billion by 2019 as the result of generic competition, making it the biggest victim of the pharmaceutical industry’s current patent cliff,” Dion said.