Pfizer, the world’s largest drug company, revealed Tuesday a cost cutting program it says has been made necessary by changes in the industry and uncertainties over the growth of profits.

The company said it’s earnings will fall this year, coming in below Wall Street expectations.

The $4 billion in reductions will take the form of reorganizing its sales operations, not filling positions vacated by retirement or resignation, introducing more efficiency in research operations, and a general streamlining of its worldwide operations.

At least part of its reorganization will reflect the much greater importance of government purchase of drugs in the U.S. in relation to the Medicare program of health care for the elderly and more of an emphasis on preventative health activities in association with large companies and the Medicare program.

Pfizer has instituted this program of cost cutting partly due to the pending expiration of a number of its drug patents, as well as over concerns revolving around pricing and safety issues, regulation, and government intervention in how drug companies operate.