Antihypertensive effect may be enhanced by other antihypertensives. Increase in serum K w/ K-sparing diuretics, K supplements, K-containing salt substitutes or other drugs that may increase K levels (eg, heparin). Reversible increase in serum lithium conc & toxicity during concomitant use of lithium w/ ACE inhibitors. Antihypertensive effect may be attenuated by NSAIDs eg, indomethacin, selective COX-2 inhibitors, ASA & non-selective NSAIDs. Increased risk of worsening renal function w/ concomitant use of AIIA & NSAIDs.