Drug Interactions between arsenic trioxide and patiromer

ADJUST DOSING INTERVAL: Patiromer can bind to some orally administered drugs, which may decrease their gastrointestinal absorption and reduce their effectiveness. According to the manufacturer, out of 28 drugs that were tested in in vitro binding studies, 14 did not show an interaction with patiromer (acetylsalicylic acid, allopurinol, amoxicillin, apixaban, atorvastatin, cephalexin, digoxin, glipizide, lisinopril, phenytoin, riboflavin, rivaroxaban, spironolactone, and valsartan). Twelve of the 14 drugs that did show an in vitro interaction were subsequently tested in in vivo studies with healthy volunteers, which revealed no changes in systemic exposure when coadministered with patiromer (amlodipine, cinacalcet, clopidogrel, furosemide, lithium, metoprolol, trimethoprim, verapamil, and warfarin). Patiromer was found to decrease systemic exposure of coadministered ciprofloxacin, levothyroxine, and metformin. However, no significant interaction occurred when patiromer and these drugs were dosed 3 hours apart.

MANAGEMENT: Patiromer should be administered with food at least 3 hours before or 3 hours after other oral medications. Alternatives to patiromer or the other medications should be considered if adequate dosing separation is not possible. Otherwise, clinical response and/or blood levels should be monitored where possible.