Healthy Men on Paxil 'Lose the Juice'

San Fransisco, CAA study released during the second weekend in November (and yet to be published) provides new concern for couples hoping to conceive—especially if the prospective father happens to be on Paxil.

Paroxetine (Paxil) is a member of the selective serotonin reuptake inhibitor (SSRI) class of antidepressants, and has been found to increase DNA fragmentation in sperm. Researchers view the five-fold increase in the number of men who developed abnormal sperm DNA as "troubling," and "suggests an adverse effect on fertility," according to co-investigator Dr. Cigdem Tanrikut, a researcher with Harvard Medical School in Boston.

What's more, paroxetine was found to be associated with 'significant' sexual dysfunction. Nearly half reported a problem having a successful ejaculation, and one third of the men participating in the study reported erectile dysfunction. While the ages of the participants were not disclosed, it was noted in the study that the 35 men who participated were healthy, with no reports of difficulty prior to taking Paxil.

"DNA integrity is crucial to normal fertility," Tanrikut said. For example, increased DNA fragmentation of sperm increases the risk of failure of intrauterine insemination.

In other words, the ability to get pregnant. What's more, "abnormal sperm DNA integrity even affects pregnancy outcomes of the most advanced assisted reproductive technologies, such as in vitro fertilization (IVF)," she added in comments reported by Reuters. "In fact, it is the only male factor finding that has been shown to affect intracytoplasmic sperm injection (ICSI) results."

The researchers were quick to point out that the damage emerging in association with sperm DNA is unlike anything seen before. In other words, most agents which have an effect on sperm succeed in lowering the sperm count. A lower sperm count makes the possibility of a pregnancy all the more challenging.

However, with Paxil it seems to be a new day, with a whole new modus operandi. What the drug succeeds in doing is slowing the transport of the sperm through the body. This "novel mechanism of damage," says Dr. Peter N. Schlegel of Weill Medical College of Cornell University in New York, effectively weakens the sperm by allowing things such as advanced temperatures as it migrates at a slower pace than normal—which also increases the aging factor.

Sperm has a very narrow shelf life. If it's too hot, or too old it is weakened. The latter can negatively affect a successful pregnancy by winding up in the ejaculate much later than it should have been, for maximum effect. In some cases, researchers have found that ejaculate in healthy males taking Paxil contain no sperm whatsoever, such is the extent of the slowing.

It should be noted that Paxil might not be the only suspect. SSRIs in general may have a similar impact, and researchers are planning larger studies with other SSRI antidepressants, in an effort to more conclusively study the issue.

Tests were conducted on semen samples obtained prior to starting paroxetine and after 4 weeks of treatment. The average DNA fragmentation score increased from 13.8 percent before paroxetine was begun to 30.3 percent at week 4, a statistically significant amount.

And while the study did not directly address and evaluate male fertility, the clinical trial was nonetheless. "the first study to assess the impact of an SSRI on semen parameters in healthy men," Dr. Tanrikut said. Thirty-five men took paroxetine for 5 weeks. The drug was administered in once-daily doses of 10 mg the first week, 20 mg in the second week, 30 mg the third and fourth week, and 20 mg in the fifth week.

The paper implicating Paxil with the fertility issue was presented at the 64th annual meeting of the American Society for Reproductive Medicine, held November 10th in San Francisco.