Evaluation of QTc prolongation and dosage effect with citalopram

Recently, controversy has surrounded a 2011 Food and Drug Administration warning against using citalopram at doses >40 mg/day due to QTc prolonging effects.

Patients ≥18 years old at the VA North Texas Health Care System were included in this retrospective review if they had received at least 1 prescription for a 30-day supply of citalopram between January 1, 2007, and February 29, 2012, and had a baseline electrocardiogram (ECG) within 1 year before initiation or dose increase of citalopram and at least 1 repeat ECG within 3 months after citalopram initiation or dose increase. The primary endpoint was the prevalence of QTc prolongation (QTc interval ≥470 ms for men and ≥480 ms for women) after initiation or a dose increase of citalopram. For secondary objectives, Fisher exact tests were used determine if there was a dose-dependent difference in prevalence of QTc prolongation among the whole study sample and among the subgroup of patients ≥60 years old.

Among the entire study sample, QTc prolongation was identified in 12 patients (16.4%) after initiation or a dose increase of citalopram. In the subgroup of patients ≥60 years old, QTc prolongation was identified in 7 patients (21.9%). Prevalence of QTc prolongation increased with dose in the entire study population (P = .016) and in patients ≥60 years (not significant).

This retrospective study suggests that citalopram produces a dose-dependent increase in QTc interval.