Antihypertensive effects may be potentiated by drugs or other agents that lower BP. Additive hyperkalaemic effect w/ K supplements, K-sparing diuretics or other drugs that can cause hyperkalaemia. Increased risk of renal impairment w/ NSAIDs. May increase serum conc of digoxin. Concomitant use w/ other AIIA metabolized by cytochrome P450 isoenzymes.