Wholesale prices for brand-name prescription drugs are rising so high they might work against the benefits of the new drug benefit that is expected to take effect this January, according to AARP, which recently released a study on the wholesale cost of prescription drugs.

Prices expanded by 7.1% between 2003 and 2004, researchers from the AARP Public Policy Institute and the PRIME Institute found. They examined the wholesale prices for 195 brand-name and 75 generic medications commonly used by adults 50 and older.

The Pharmaceutical Research and Manufacturers of America criticized the AARP report, citing Consumer Price Index data that shows that prescription drug prices are increasing about 4% annually.

While Medicare beneficiaries will receive help when the new Medicare drug benefit kicks in, “rising prices are making that less and less of a potential benefit,” said John Rother, director of policy and strategy at AARP.

Between 2003 and 2004, the wholesale price of the anti-cholesterol medication Lipitor increased 6.4%; the arthritis drug Celebrex increased by 6.6%; the hypertension medication Norvasc rose 4.2% and the cost of heart disease treatment Plavix expanded by 7.9%. Wholesale prices for prescriptions between these two years rose 2.5 times the general inflation rate of 2.7%.