Drug Interactions between amoxicillin / clarithromycin / lansoprazole and ceftriaxone

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Coadministration of ceftriaxone with lansoprazole has been associated with prolongation of the QT interval and increased risk of ventricular arrhythmia, cardiac arrest, and death in hospitalized patients. The precise mechanism of interaction has not been established, although ceftriaxone and lansoprazole in combination have been shown in patch-clamp electrophysiologic experiments to block the human ether-a-go-go-related gene (hERG) potassium channel at clinically relevant concentrations, which is a common mechanism for drug-induced QT prolongation. In a single-center retrospective cohort study consisting of 380,000 patients, investigators found the combination of ceftriaxone and lansoprazole was associated with significant prolongation of the corrected QT (QTc) interval, and patients treated with the combination were 1.4 times more likely to have a QTc interval greater than 500 msec relative to treatment with either drug alone. On average, QTc intervals were 12 msec longer in men and 9 msec longer in women who were receiving ceftriaxone and lansoprazole concurrently compared with patients receiving either drug alone. These observations were not reported for cefuroxime and lansoprazole, the negative control used in the study. In another retrospective cohort study of 31,152 patients receiving ceftriaxone therapy with a proton pump inhibitor (PPI) in 13 hospitals in Ontario, Canada, over a 7 year period, concomitant use of lansoprazole (n=3747; 12%) was associated with adjusted absolute risk increases of 1.7% for ventricular arrhythmia or cardiac arrest and 7.4% for all-cause in-hospital mortality compared with use of other PPIs (n=27,405; 88%). Overall, ventricular arrhythmia or cardiac arrest occurred in 126 patients (3.4%) in the lansoprazole group and 319 patients (1.2%) in the other PPI group, while in-hospital mortality occurred in 746 patients (19.9%) in the lansoprazole group and 2762 patients (10.1%) in the other PPI group. However, these events could not be definitively linked to QTc interval prolongation, since QTc intervals on electrocardiograms were not captured in the study. The interaction was also independently reported in a patient receiving ceftriaxone 2 gm/day for pneumonia who developed QTc prolongation following the addition of lansoprazole 30 mg/day for epigastralgia. The patient's QTc interval was 422 msec on admission and 417 msec three days after starting ceftriaxone, but increased to 475 msec after two days of combined treatment despite no changes in electrolytes, echocardiography findings, or further drug use. Two days after lansoprazole was stopped and replaced with pantoprazole, QTc returned to normal at 424 msec while ceftriaxone was continued.

MANAGEMENT: Until more information is available, prescribers should consider avoiding the concomitant use of ceftriaxone and lansoprazole when possible, particularly in the elderly and patients with underlying risk factors for QT prolongation such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). Patients coadministered these medications should have renal function, serum electrolytes, and electrocardiograms monitored.

Clarithromycin may increase the blood levels and side effects of lansoprazole in some people. Contact your doctor if you experience diarrhea or other intestinal problems. You may need a dose adjustment if you take both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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