WASHINGTON (CNN) -- Consumers in the United States pay more for recently-developed antidepressant and anti-psychotic prescription drugs than consumers in other countries, according to a study released Wednesday by the group Public Citizen.

According to the study, consumers in the United States could have saved $2.1 billion in 1996 if they would have purchased the drugs in other countries, according to comparisons of prices in the United States and the average price of the same drugs in 17 countries studied.

Researchers looked at prices for eight drugs, and found the average cost to pharmacists was 1.7 to 2.9 times higher in the United States than in 17 other countries studied.

For instance, the study indicates a 30-day supply of fluoxetine, commonly known as Prozac, costs $72.16 in the United States, $25.93 in Spain, with an average cost of $34.40 in the countries surveyed.

A 30-day supply of clozapine costs pharmacists $317.03 in the United States and $51.94 in Spain, with an average cost in other countries of $111.20.

A 30-day supply of olanzapine costs $324.08 in the United States, $76.87 in Spain, with an average cost of $163.10 in the countries surveyed.

A 30-day supply of paroxetine, commonly known as Paxil, costs $63.78 in the United States, $27.59 in France, with an average cost of $37.00 in the countries surveyed.

According to Public Citizen, the high costs of these recently-developed drugs may limit their availability to the public, especially since several states' Medicaid programs, community mental health centers and managed care companies have limited use of the newer drugs in an effort to control costs.

The study also notes that all the countries studied, except the United States, have national health insurance programs, which, it contends, may allow those countries to negotiate lower prices with pharmaceutical companies.

The study finds that pharmaceutical companies in the United Kingdom make a 20 percent profit on the drugs studied, while the profit margin on the same eight drugs in the United States is 42 percent.