LONDON - Doctors have long assumed that most antidepressants are interchangeable.
But according to a new study, Zoloft and Cipralex work slightly better than 10 other popular drugs, and should be psychiatrists' first choice for patients with moderate to severe depression.
Previous research found few differences between antidepressants. A U.S. government study in 2006 concluded that patients with major depression did equally well on different drugs.
But in a paper published online Thursday in the Lancet medical journal, two antidepressants came out on top, though only marginally.
International doctors examined more than 100 previous studies on a dozen antidepressants, which included nearly 26,000 patients from 1991 to 2007.
They found that Zoloft, developed by Pfizer Inc., and Cipralex, developed by Forest Laboratories in the U.S. and Danish drugmaker H. Lundbeck A/S in Europe, were the best options when considering benefits, side-effects and cost. In contrast, Pfizer's Edronax was the least effective.
The other drugs tested were Celexa, Cymbalta, Efexor, Ixel, Luvox, Prozac, Seroxat, Remeron and Zyban.
"The bottom line is that there is a rational hierarchy when prescribing antidepressants," said Dr. Andrea Cipriani, the study's lead author, of the University of Verona in Italy.
The experts judged a drug to be successful if it reduced patients' baseline depression scores on two standardized tests by at least half and if patients had not stopped taking it within two months.
Side-effects for the various drugs include nausea, sleeplessness and sexual dysfunction.
Cipriani said all the antidepressants were effective, and that the differences between them were not huge. "If a patient is taking a drug and doing well, he should not stop and switch drugs," he said.
Irving Kirsch, a professor of psychology at Britain's University of Hull, predicted the study would affect doctors more than patients.
"Doctors will probably prescribe (Zoloft and Cipralex) more often, but patients may not see a big difference between one drug versus another," he said. Psychiatrists should consider other ways to help patients, like behavioural therapy, Kirsch said.
The study was paid for by the authors' academic institutions in Britain, Greece, Italy, and Japan. Cipriani has not received any grants from pharmaceuticals. Several of his co-authors reported receiving funding from various makers of antidepressants.
