Drug Interactions between amoxicillin / clarithromycin / vonoprazan and ramelteon

MONITOR: Coadministration with potent inhibitors of CYP450 3A4 and/or 2C9 may increase the plasma concentrations and pharmacologic effects of ramelteon, which is partially metabolized by these isoenzymes. In healthy volunteers, administration of a single 16 mg oral dose of ramelteon following pretreatment with the potent CYP450 3A4 inhibitor ketoconazole (200 mg orally twice daily for 4 days) increased ramelteon peak plasma concentration (Cmax) by 36% and systemic exposure (AUC) by 84% compared to administration of ramelteon alone. Likewise, coadministration with fluconazole, a potent CYP450 2C9 inhibitor, resulted in an increase of approximately 150% in the Cmax and AUC of ramelteon following a single 16 mg oral dose. Similar pharmacokinetic changes were also observed with its biologically active metabolite, known as M-II.

MANAGEMENT: Caution is advised if ramelteon is prescribed in combination with potent inhibitors of CYP450 3A4 (e.g., itraconazole, ketoconazole, posaconazole, voriconazole, conivaptan, delavirdine, nefazodone, protease inhibitors, ketolide and certain macrolide antibiotics) and/or CYP450 2C9 (e.g., fluconazole, gemfibrozil, imatinib, miconazole). A reduction in the ramelteon dosage may be necessary in patients who experience excessive sedation.

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.