This high dosage can alter the drugs' effectiveness, worsen their side effects, and may contribute to the skyrocketing cost of prescriptions.
The researchers in the study looked at changes in labeling for all new FDA-approved drugs between 1980 and 1999, and discovered that dosages in 21 percent of the drugs had been changed, leading them to believe that "this pattern may represent a systematic flaw in pre-marketing dosage evaluation."
The news release says that "In the modern drug development process, great pressure is placed on defining a drug dosage early in the clinical evaluation stage, when information about the drug and its actions is sparse," and that "these overestimated doses are discovered at various times after the drug is introduced into medical practice."
In a separate study, researchers at two Dutch universities have found a similar phenomenon in prescribed dosages.
The report concludes that "all the researchers agree that further study on the process of dose-selection is needed to ensure that patients get the optimal dose right from the start."