Antidepressant Effexor Beats Prozac and Zoloft
March 16, 2000 (New York) — In two head-to-head comparison studies, people with major depression treated with Effexor (venlafaxine) were more likely to recover completely than those treated with either Prozac (fluoxetine) or Zoloft (sertraline).
“These findings are important because up until [now], there’s been a general feeling that antidepressant drugs are all equal in [effectiveness],” says lead author of the Prozac investigation Richard L. Rudolph, MD. “In the last few years, there’s been mounting evidence that this may not be entirely true, particularly when you look at [recovery rates].”
Researchers are starting to see evidence that certain classes of drugs, particularly those that act on two brain chemicals, may be better than those antidepressants that act on just one, Rudolph tells WebMD. Rudolph is senior director of clinical research and development at Wyeth-Ayerst Research, which supported both studies. Wyeth-Ayerst Pharmaceuticals manufactures Effexor.
There are multiple ways in which antidepressants work, explains Richard Shelton, MD, of the psychiatry department of Vanderbilt University in Nashville, Tenn. Older medicines like the tricyclic group act by influencing two important chemicals in the brain thought to contribute to mood control: norepinephrine and serotonin. “These medicines are very effective in reducing symptoms of depression, but have many other side effect problems,” he says.
Medicines like Prozac, however, have reduced side effects because they only act on serotonin. They are called selective serotonin reuptake inhibitors (SSRIs). “These medicines clearly reduced side effects, but there have been concerns about their effectiveness relative to older medicines,” Shelton says.
Some newer drugs, including Effexor, were developed to have the increased benefits associated with acting on two brain chemicals, but have fewer side effects than the older tricyclics, says Shelton, who reviewed the research for WebMD.
In a study co-written by Rudolph in the December 1999 Journal of Affective Disorders that compared Effexor with Prozac, patients with depression were assigned to eight weeks of treatment with extended release Effexor, Prozac, or a placebo (sugar pill). The greatest improvement was noted in the Effexor group and the least in the placebo group. The investigators found that 37% of the Effexor-treated patients went into full recovery, as compared with 22% of the Prozac-treated patients and 18% of those taking the sugar pills.
In the second study from the February issue of the Journal of Clinical Psychiatry, Olli-Pekka Mehtonen, MD, and colleagues at the University of Tampere in Tampere, Finland, found that Effexor produced both a significantly better response rate and recovery rate than Zoloft. After eight weeks of treatment, the response rates for all patients were 83% with Effexor and 68% for Zoloft, and the recovery rates were 68% and 45%, respectively
“There’s beginning to be fairly compelling evidence that … dual-action drugs are more effective than single-action drugs in a range of psychiatric disorders. The [Journal of Affective Disorders] paper is one very good demonstration of that,” says Peter Silverstone, MD, director of the psychopharmacology research unit at the University of Alberta in Canada. Silverstone, who is not affiliated with either study, tells WebMD that the dual-action drugs have been shown to be effective for severe depressive disorder, mild-to-moderate depressive disorders, and anxiety.
Shelton agrees that drugs that work on two brain chemicals are very promising for the treatment of depression. “The two studies cited showed a small but clinically and statistically significantly greater effect for Effexor over the other two drugs. Not all studies of this type have shown the same effects,” Shelton says. “The current evidence indicates that in more severely depressed persons, the combined agents are more effective, but further study is needed.”
- In a study on patients who suffer from major depression, the drug Effexor was more likely than Prozac or Zoloft to result in full recovery.
- Researchers suspect Effexor is more effective because it acts on two different brain chemicals that transmit messages and are thought to control mood.