Creams that require a prescription have the best track record, including tretinoin, tarazotene, and their brand-name versions.

All three drugs are available in a generic form, however, and sales of the three brand-name versions are falling.

A generic beta blocker costs less than $10 a month, while brand-name versions generally cost $20 to $40.

The study doesn't specify whether the generic or brand-name versions were used.

One of the four was the company's brand-name version, Synthroid, which is the third most widely prescribed drug in the United States.

Although generics typically cost far less than brand-name versions, the makeup of the two can differ.

He acknowledged that the generic drugs cost much less than the brand-name versions, even after the price increases.

Some six million prescriptions for the generic and brand-name versions were filled in 1993.

As an additional safeguard, the agency is sampling the brand-name versions of the drugs.

Triomune costs as little as $140 a year per patient, compared with about $562 for the brand-name versions in the 3-in-1 pill.