A new study by scientists in the U.S., Canada and Britain has called into question the effectiveness of anti-depressant medications, including the popular Prozac and Paxil.
According to the study, which included a comprehensive review of data from trials conducted before the drugs were approved in the U.S., the antidepressants work no better than placebos in many patients, and appear to help only those who are severely depressed.
The researchers obtained the data from all the clinical trials, both published and unpublished, submitted to the U.S. Food and Drug Administration for the licensing of four antidepressants, including Eli Lilly’s Prozac, also known as fluoxetine, Wyeth’s Effexor, also called venlafaxine, GlaxoSmithKline’s Paxil, also called Seroxat or paroxetine, and Bristol-Myers Squibb’s drug Serzone, also called nefazodone, which is no longer sold in the United States. The medications are all known as selective serotonin reuptake inhibitors, or SSRIs.
The research team, led by Irving Kirsch of the University of Hull, then examined whether a person’s response to these drugs centered on how depressed they were before starting treatment.
The researchers found that compared with placebo, these new-generation antidepressant medications did not yield clinically significant improvements in patients with initially moderate or even very severe depression.
The study showed that considerable benefits occurred only in the most severely depressed patients.
“Drug-placebo differences in antidepressant efficacy increase as a function of baseline severity, but are relatively small even for severely depressed patients. The relationship between initial severity and antidepressant efficacy is attributable to decreased responsiveness to placebo among very severely depressed patients, rather than to increased responsiveness to medication,” the researchers wrote in a report about the study.
“Although patients get better when they take antidepressants, they also get better when they take a placebo, and the difference in improvement is not very great. This means that depressed people can improve without chemical treatments,” Kirsch said in a statement.
However, Paxil spokes woman Mary Ann Rhyne told Reuters the study only looked at data submitted prior to the drug’s U.S. approval.
“The authors have failed to acknowledge the very positive benefit these treatments have provided to patients and their families who are dealing with depression and they are at odds with what has been seen in actual clinical practice,” Rhyne said.
“This analysis has only examined a small subset of the total data available, while regulatory bodies around the world have conducted extensive reviews and evaluations of all of the data available,” she added.
Wyeth spokesman Doug Petkus said he had not seen the study and could not comment.
—
On the Net:
The study was published this week in the journal Public Library of Science (PLOS) Medicine. The full report can be viewed here.
Comments