Increased risk of lactic acidosis w/ topiramate or other carbonic anhydrase inhibitors eg, zonisamide, acetazolamide or dichlorphenamide. Hyperglycemia & loss of glycemic control w/ thiazides, other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, OCs, phenytoin, nicotinic acid, sympathomimetics, Ca-channel blockers & INH. Saxagliptin: Increased plasma conc w/ strong CYP3A4/5 inhibitors eg, ketoconazole, atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin. Hypoglycemia w/ insulin secretagogues or insulin. Metformin: Increased systemic exposure w/ organic cationic transporter-2 or multidrug & toxin extrusion inhibitors eg, ranolazine, vandetanib, dolutegravir, cimetidine. Potentiated effect w/ alcohol.