Drug Interactions between amoxicillin / clarithromycin / lansoprazole and nilotinib

GENERALLY AVOID: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of nilotinib, which is primarily metabolized by the isoenzyme. In healthy subjects receiving the potent inhibitor ketoconazole (400 mg once daily for 6 days), nilotinib systemic exposure (AUC) was increased approximately 3-fold. Because nilotinib is associated with concentration-dependent prolongation of the QT interval, increased levels may potentiate the risk of ventricular arrhythmias such as torsade de pointes and sudden death.

MANAGEMENT: Concomitant use of nilotinib with potent CYP450 3A4 inhibitors such as itraconazole, ketoconazole, posaconazole, voriconazole, conivaptan, nefazodone, cobicistat, delavirdine, protease inhibitors, and ketolide and certain macrolide antibiotics should generally be avoided. Some authorities recommend avoiding concomitant use of nilotinib during and for 2 weeks after treatment with itraconazole. Should treatment with a potent inhibitor be required, the manufacturer recommends that nilotinib therapy be withheld temporarily. If concomitant use is unavoidable, a reduction of the nilotinib dosage to 400 mg once daily should be considered. Based on pharmacokinetic studies, this dosage is predicted to adjust the nilotinib systemic exposure (AUC) to the range observed without inhibitors. However, clinical data are lacking. Patients should have frequent ECGs and be monitored for arrhythmias when QT interval is prolonged. A QTc interval exceeding 480 msec will require suspension of nilotinib therapy and immediate action to correct any concomitant risk factors before resuming treatment. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope. Following discontinuation of the potent CYP450 3A4 inhibitor, a washout period of approximately one week should be allowed before the nilotinib dosage is adjusted upward to the original dosage.

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.

GENERALLY AVOID: Chronic use of inhibitors of the proton pump (PPIs or potassium-competitive acid blockers [PCABs]) may significantly decrease the oral bioavailability of nilotinib. The mechanism is decreased solubility of nilotinib due to increased gastric pH. Nilotinib's solubility is pH dependent and it is insoluble at a pH of 4.5 or higher.

MANAGEMENT: The concomitant use of PPIs or PCABs should generally be avoided during therapy with nilotinib.

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.