Pfizer Inc., the world''s biggest drug company, is laying off up to 800 scientists this year in its latest effort to refocus disappointing research efforts and cut its massive overhead ahead of an anticipated crash in revenue. Pfizer plans to reduce its global research staff of about 10,000 people by 5 percent to 8 percent this year, according to the Associated Press. The move comes after the company announced in September it was narrowing its research focus to six disease areas -- Alzheimer''s, cancer, schizophrenia, pain, inflammation and diabetes -- and abandoning new research in other areas. Some researchers were shifted from other areas into the six new core areas. Surprisingly, one of the areas abandoned was cardiovascular disease, where Pfizer had been a dominant player with its $13 billion-a-year cholesterol fighter Lipitor, the world''s top-selling drug. But Lipitor -- which brings in just over one-fourth of Pfizer''s roughly $50 billion in annual revenue -- is expected to face generic competition in late 2011. Efforts to come up with a successor drug failed, including the flameout of once-promising torcetrapib after it was linked to heart problems in late-stage human testing. Already, Lipitor sales have dipped slightly, apparently partly due to consumers trying a much-cheaper generic form of a similar drug, Zocor. The cuts are not due to the recession but to the long-term problems plaguing the entire drug industry. Those include stiffer generic competition and a general lack of research productivity. Last fall, Pfizer said it was reorganizing its business units, including replacing its current geographic divisions with new ones centered on primary care, specialty care and operations in emerging markets. Under a major restructuring begun in January 2007, Pfizer has eliminated roughly 14,600 jobs, leaving about 83,400 workers, and closed eight plants or other sites. Research areas that Pfizer is exiting include anemia, bone health, gastrointestinal disorders, obesity, liver disease, osteoarthritis and peripheral artery disease.