No difference in side-effects when switching or adding antidepressants

Patients with major depression who fail to see improvement after taking an antidepressant often have their initial medication switched or combined with a second drug. Many clinicians weigh the possibility of adverse side effects when deciding between strategies. New research in the latest issue of General Hospital Psychiatry now suggests one strategy may not be any more likely to be harmful than the other.

More than 16 percent of U.S. adults are diagnosed with depression at some point during their lives and antidepressants are commonly used to treat them, according to a 2005 study in the Archives of General Psychiatry. However, research in both the American Journal of Psychiatry (2006) and the Annals of Internal Medicine (2008) has shown that only 30 to 50 percent benefit from initial antidepressant treatment. Standard second-step options are adding a new antidepressant while continuing to take the original one, an approach known as augmenting, or switching to a new antidepressant.

Headaches, difficulty sleeping and sexual dysfunction are among the common side effects of antidepressants. It was previously assumed that either changing or adding a second medication might exacerbate these effects. But new research unexpectedly found only minimal differences in the adverse side effects resulting from either strategy.

“We believed the augment group would have more side effects than the switch group,” said study author Richard Hansen, Ph.D., head of the department of pharmacy care systems at Auburn University.

In the study, nearly 1,300 patients who had not been successfully treated with just the antidepressant citalopram were divided into two groups. One group had their citalopram augmented with bupropion or buspirone. The second group was switched to bupropion, sertraline or venlafaxine. Patients were followed for about five visits over 14 weeks to evaluate what, if any, side effects occurred.

The researchers found that although painful urination and problems with sexual dysfunction were more common in the augment group than the switched group, the differences were not statistically significant.

Hansen said the study should give physicians treating depression a clear take-away message: “For treatment-resistant depression, the decision to augment or switch medications should be based on individual patient’s clinical status, as well as the possible benefits and risks of each treatment.”

Alan Schmetzer, M.D., interim chairman of the department of psychiatry at Indiana University School of Medicine in Indianapolis, agreed and said the likelihood of his patients responding to the first medication at the first dose he prescribes is around 40 to 50 percent.

“This study tries to answer an important question to which there is currently no research available,” said Schmetzer. “It’s worthwhile because if we knew it was harder on patients to do the augmentation strategy, then we would first try switching all of the time.”