Prozac, Effexor, and Paxil may only be effective in the most severely depressed patients. In a recent study conducted by British researchers on the effect of some antidepressants, it seems that antidepressant medications may only really be truly effective in the most severely depressed of patients. The study also found that these antidepressant medications actually work no better than placebos in many patients taking them and that the patients fared the same whether on a placebo or on one of the antidepressant medications represented in the study. The research was led by Irving Kirsch of the University of Hull and reviewed a series of studies—both published and unpublished—on four specific antidepressants.
The study examined the question of whether a person’s response to these anti-depressant medications was dependent on how depressed the patients were before they received treatment for their depression. All four medications studied are the so-called selective serotonin reuptake inhibitors—commonly known as SSRIs—and were specifically Eli Lilly and Company’s Prozac, which is also known as fluoxetine; Wyeth’s Effexor, which is also called venlafaxine; GlaxoSmithKline’s Paxil, which goes by both Seroxat and paroxetine; and Bristol-Myers Squibb Company’s drug Serzone, which is also called nefazodone. Bristol-Meyer’s Serzone is no longer marketed in the United States.
The research group discovered that when compared with placebo, these new-generation SSRI antidepressant medications did not provide any measurable, clinically significant improvements in depression in those patients who initially suffered from moderate or even very severe depression. The study did reveal, though, that the most significant benefits occurred only in the very severely of 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.
As part of their study, the researchers also obtained data on all of the clinical trials submitted to the U.S. Food and Drug Administration (FDA) for the licensing of the four antidepressant SSRI drugs. “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 concerning the findings of the study. But, Mary Ann Rhyne, a spokeswoman for Paxil maker GlaxoSmithKline, argued that 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.
Doug Petkus, a spokesman for Wyeth, the maker of Effexor, said he had not yet seen the recent study and could not comment on its contents.