The widely prescribed antidepressant Celexa can cause potentially fatal disruptions to heart rhythms when taken in high doses, the Food and Drug Administration said Wednesday.
In an online posting, the FDA advised doctors to no longer prescribe Celexa in doses of greater than 40 milligrams a day, warning that high doses of the drug could alter the electrical activity of the heart and lead to an abnormal heartbeat. The FDA also rejected a claim, previously included on the drug's label, that some depression sufferers could require dosages of up to 60 milligrams per day.
Studies did not show a benefit in the treatment of depression at doses higher than 40 mg per day, the posting said.
People who have preexisting heart conditions or low levels of potassium or magnesium in their blood face an elevated risk of Celexa-induced heart abnormalities, the FDA said. The agency advised people taking the drug to be on the lookout for irregular heartbeat, shortness of breath, dizziness, or fainting.
Celexa, known generically as citalopram, is part of a commonly presribed class of antidepressants called selective serotonin reuptake inhibitors (SSRIs), that also encompasses Paxil, Prozac and Zoloft, all popular medications. SSRIs act on neurotransmitters, which regulate communication between different brain cells. The theory is that blocking a receptor in the brain that would otherwise reabsorb the neurotransmitter serotonin, SSRIs help brain cells communicate more effectively and thus boost mood.