May result in hyperkalemia w/ other drugs that raise serum K levels. Increased serum conc & toxicity of lithium. May result in deterioration of renal function, including possible acute renal failure, w/ NSAIDs including selective COX-2 inhibitors, in patients who are elderly, vol-depleted (including those on diuretic therapy), or w/ compromised renal function. Antihypertensive effect may be attenuated by NSAIDs. Dual blockade of the RAS w/ ACE inhibitors or aliskiren is associated w/ increased risks of hypotension, syncope, hyperkalemia, & changes in renal function (including acute renal failure). Avoid use w/ aliskiren in patients w/ renal impairment (GFR <60 mL/min).