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Certain antidepressants may prolong QT interval
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New data published in BMJ confirm a modest prolongation of QT interval with citalopram and other selective serotonin reuptake inhibitors.
The findings support recent warnings from the FDA about QT prolongation with citalopram (Celexa, Forest Laboratories) at higher doses and suggest that some other selective serotonin reuptake inhibitors (SSRIs) may have similar effects.
In light of the FDA warnings, a team of US researchers explored the association between prolonged QT interval and antidepressant use in a diverse clinical population. Using electronic health records, they identified 38,397 adults from a large New England health care system who had an ECG after an antidepressant or methadone prescription between February 1990 and August 2011. Methadone was included in the analysis because it is known to contribute to a longer QT interval, according to the researchers.
Their evaluation yielded a small but significantly longer QT interval for citalopram (P<.01) and escitalopram (Lexapro, Forest Laboratories; P<.001), as well as for methadone and amitriptyline (P<.001), a tricyclic antidepressant. This effect increased at higher doses (citalopram: 10 mg to 20 mg, mean QTc increase of 7.8 ms; 20 mg to 40 mg, mean QTc increase of 10.2 ms), suggesting a dose-response association, according to study results.
“Nearly one in five patients treated with these antidepressants who underwent electrocardiography had QT intervals which would be considered abnormal,” the researchers said. However, the clinical significance of this is unknown, they added.
In contrast, a shorter QT interval was observed with bupropion (Wellbutrin/Zyban, GlaxoSmithKline; P<.05), even at higher doses.
Other standard antidepressants, including fluoxetine (Prozac, Eli Lilly), paroxetine (Paxil, GlaxoSmithKline) and sertraline (Zoloft, Pfizer) had no effect on QT interval, and further analyses did not significantly alter the results, according to a press release.
“It was important to confirm the effects of citalopram — one of the most widely prescribed antidepressants in the United States — because the FDA warning really gave us minimal clinical guidance,” Roy Perlis, MD, of the Massachusetts General Hospital department of psychiatry, said in a press release. “The impetus for this study came directly from the phone calls we received from colleagues and from patients taking citalopram asking what they should do. We realized that to get a satisfying answer, we needed to get more data.”
An additional finding from this study was that electronic health record data “may be a useful method of identifying potential risk associated with treatments,” according to the researchers.
Disclosure: See the study for a full list of the researchers’ relevant financial disclosures.
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