Ciprofloxacin × Sertraline

Both drugs prolong the QT interval. Sertraline does so in a concentration-dependent way: at twice the maximum recommended dose the largest mean increase was 10 ms (sertraline label of the US Food and Drug Administration, FDA). Ciprofloxacin, like other fluoroquinolones, prolongs the QT interval; ventricular arrhythmias and torsades de pointes have been reported with it, mostly in patients with risk factors (ciprofloxacin SmPC). The effects add up; the risk is higher with congenital long QT, low potassium or magnesium, heart disease, bradycardia, in older people and in women (ciprofloxacin and sertraline SmPCs).

QT prolongation on ECG. Dizziness, syncope, palpitations. Rarely: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.

The US Food and Drug Administration (FDA) label of sertraline says to avoid drugs known to prolong the QT interval; its examples include antibiotics, among them fluoroquinolones (sertraline FDA label). European SmPCs are softer and allow the combination with caution: sertraline and ciprofloxacin are used carefully in patients with risk factors for QT prolongation, such as congenital long QT, low potassium or magnesium, heart disease or bradycardia, and ciprofloxacin also in older people and women (sertraline and ciprofloxacin SmPCs). Avoid the combination where possible; if ciprofloxacin is still needed, assess these risk factors before starting.