U.S. pharmacies should generate more than $350 billion in prescription-drug revenue by 2015, an increase of some $100 billion from last year, with expensive specialty medications for chronic or complex illnesses helping to fuel the growth, according to a pharmaceutical supply-chain consulting firm.

Pembroke Consulting, in a new industry report, also predicts that while a coming wave of generic prescription drugs will enhance pharmacy profits, those generic-drug profits will be pressured by a price war sparked by Wal-Mart Stores Inc.'s (WMT) $4 generics program and by the use of new contracting strategies.

Pharmacy revenue should grow by an average of 4.9% a year between now and 2015, a rate slightly lower than that projected by the federal government, Philadelphia-based Pembroke said.

"This forecast reflects overall growth in demand for prescription pharmaceuticals," the firm said. "Generic drugs will soon be more than 80% of U.S. prescriptions, slowing pharmacies' revenue growth. However, expensive specialty pharmaceuticals will grow to be at least 30% of total pharmacy revenues, adding to revenue growth."

The U.S. has nearly 54,000 retail pharmacy locations, including drug stores, mail-order pharmacies, supermarkets and mass merchants, Pembroke said. The pharmacies generated nearly $254 billion in revenue last year, according to the firm, which estimates pharmacy revenue of more than $354 billion in 2015.

The top U.S. pharmacies ranked by total pharmacy revenue in 2008 were CVS Caremark Corp. (CVS), Walgreen Co. (WAG), Medco Health Solutions Inc. (MHS), Rite Aid Corp. (RAD) and Wal-Mart, according to Pembroke. The firm expects chain drug stores to expand their market share and predicts Wal-Mart will become the third-largest retail pharmacy chain possibly by next year.

Revenue at independent pharmacies will be flat despite overall market growth, although that segment of the industry should remain viable, Pembroke said. While revenue at mail-order pharmacies should grow due to higher use of specialty drugs, overall growth in mail-order prescriptions will lag the market because of increased competition from retail-based pharmacies, Pembroke predicts.

Generic drugs contributed $13 billion more in gross profits to pharmacies than brand drugs did last year, Pembroke President Adam Fein said. He added in a statement, however, that the "superior profitability" of generics "will be threatened in coming years as health-care payers implement new payment benchmarks and pharmacies engage in a generic prescription drug war."

-By Dinah Wisenberg Brin, Dow Jones Newswires; 215-656-8285; dinah.brin@dowjones.com