Increased hypotensive effects w/ diuretics & other anthypertensive agents. Higher frequency of adverse events w/ ACE inhibitors or aliskiren. Increased serum K levels w/ K-sparing diuretics, K supplements, K-containing salt substitutes or other drugs increasing serum K levels eg, heparin. Reversible increased serum lithium conc & toxicity. Attenuated antihypertensive effect w/ NSAIDs eg, selective COX-2 inhibitors, ASA & non-selective NSAIDs.