Despite intense congressional and public criticism, retail prices of the brand-name drugs most commonly used by older Americans rose more than 130 times the rate of inflation between 2006 and 2015, according to a report issued Wednesday morning by the AARP Public Policy Institute.

AARP calculated the average annual cost of brand-name pharmaceuticals on the list at about $5,800 last year. Seniors took, on average, 4.5 different prescriptions every month last year. If someone used only name-brand drugs, that comes out to about $26,000, exceeding the $24,150 median annual income for Medicare beneficiaries.

The study looked only at name-brand prices, not generics.

The price increases helped drive health-insurance companies to charge higher premiums and deductibles, and stressed  taxpayer-supported programs run by Medicare and Medicaid, the report said.

Valeant Pharmaceuticals, which is under federal investigation for fraud and price gouging, was responsible for five of the six biggest price increases by percentage, according to AARP.

Since 2005, the cost of Valeant's anti-anxiety medication Ativan soared over 2,800 percent; the price of the company's skin disorder cream, Carac, inflated nearly 2,400 percent; its Wellbutrin XL for depression shot up nearly 1,800 percent, and its Zovirax cream for skin disorders increased more than 780 percent.

"Current market forces have not moderated excessive brand-name drug price increases," the report concluded, "and the resulting increases in pharmaceutical expenditures are not sustainable."