Drug Interactions between amoxicillin / clarithromycin / lansoprazole and ribociclib

GENERALLY AVOID: Ribociclib can cause dose-related prolongation of the QT interval. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). In addition, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s).

GENERALLY AVOID: Coadministration with potent CYP450 3A4 inhibitors may increase the plasma concentrations and the risk of adverse effects of ribociclib, which is primarily metabolized by the isoenzyme. In healthy subjects, administration of a single 400 mg dose of ribociclib with ritonavir (100 mg twice daily for 14 days), a potent CYP450 3A4 inhibitor, resulted in a 1.7-fold and 3.2-fold increase in ribociclib peak plasma concentration (Cmax) and systemic exposure (AUC), respectively, compared to ribociclib administered alone. In addition, administration of erythromycin, a moderate CYP450 3A4 inhibitor, is predicted to increase ribociclib Cmax and AUC by 1.3-fold and 1.9-fold, respectively. The risk of adverse effects such as infections, neutropenia, leucopenia, anemia, thrombocytopenia, nausea, vomiting, diarrhea, stomatitis, anorexia, alopecia, fatigue, headache, and abnormal liver function may be increased.

MANAGEMENT: Coadministration of ribociclib with other drugs that can prolong the QT interval and are CYP450 3A4 inhibitors should generally be avoided. Since the magnitude of QT prolongation may increase with increasing plasma concentrations of ribociclib, caution and close clinical monitoring are recommended if concomitant use with these drugs is unavoidable. Alternative agents with no or minimal CYP450 3A4 inhibitory potential are recommended whenever possible. If no alternatives exist, the dose of ribociclib should be reduced to 400 mg once daily. Following discontinuation of the potent CYP450 3A4 inhibitor, the ribociclib dosage should be returned (after at least 5 half-lives of the inhibitor) to that used prior to initiation of the inhibitor. In addition, ECGs should be assessed prior to initiation of treatment, during treatment when clinically necessary, and more frequently if QTcF prolongation occurs at any time during treatment. Ribociclib should be permanently discontinued if the QTcF interval prolongation is either greater than 500 msec or there is a greater than 60 msec change from baseline and associated with any of the following: Torsades de Pointes, polymorphic ventricular tachycardia, unexplained syncope, or signs/symptoms of serious arrhythmia.

MONITOR: Coadministration with clarithromycin may increase the plasma concentrations of lansoprazole. The proposed mechanism is clarithromycin inhibition of intestinal (first-pass) and hepatic metabolism of lansoprazole via CYP450 3A4. Although lansoprazole is primarily metabolized by CYP450 2C19 in the liver, 3A4-mediated metabolism is the predominant pathway in individuals who are 2C19-deficient (approximately 3% to 5% of the Caucasian and 17% to 20% of the Asian population). Additionally, inhibition of P-glycoprotein intestinal efflux transporter by clarithromycin may also contribute to the interaction, resulting in increased bioavailability of lansoprazole. In 18 healthy volunteers--six each of homozygous extensive metabolizers (EMs), heterozygous EMs, and poor metabolizers (PMs) of CYP450 2C19--clarithromycin (400 mg orally twice a day for 6 days) increased the peak plasma concentration (Cmax) of a single 60 mg oral dose of lansoprazole by 1.47, 1.71- and 1.52-fold, respectively, and area under the concentration-time curve (AUC) by 1.55-, 1.74- and 1.80-fold, respectively, in each of these groups compared to placebo. The AUC ratio of lansoprazole to lansoprazole sulphone, which is considered an index of CYP450 3A4 activity, was significantly increased by clarithromycin in all three groups. However, elimination half-life of lansoprazole was prolonged by 1.54-fold only in PMs. Mild diarrhea was reported in two subjects and mild abdominal disturbance in six subjects during clarithromycin coadministration. These side effects continued until day 6 and ameliorated the day after discontinuation of clarithromycin, whereas no adverse events were reported during placebo administration or after lansoprazole plus placebo. In another study, clarithromycin induced dose-dependent increases in the plasma concentration of lansoprazole in a group of 20 patients receiving treatment for H. pylori eradication. Mean 3-hour plasma lansoprazole concentration was 385 ng/mL for the control subjects who received lansoprazole 30 mg and amoxicillin 750 mg twice a day for 7 days; 696 ng/mL for patients coadministered clarithromycin 200 mg twice a day; and 947 ng/mL for patients coadministered clarithromycin 400 mg twice a day.

MANAGEMENT: Although lansoprazole is generally well tolerated, caution may be advised during coadministration with clarithromycin, particularly if higher dosages of one or both drugs are used. Dosage adjustment may be necessary in patients who experience excessive adverse effects of lansoprazole.

Although some in vitro data indicate synergism between macrolide antibiotics and penicillins, other in vitro data indicate antagonism. When these drugs are given together, neither has predictable therapeutic efficacy. Data are available for erythromycin, although theoretically this interaction could occur with any macrolide. Except for monitoring of the effectiveness of antibiotic therapy, no special precautions appear to be necessary.