Aliskiren. Digoxin. May increase serum K w/ K-sparing diuretics eg, spironolactone, eplerenone, triamterene, amiloride, K supplements or K-containing salt substitutes. Increase lithium conc. Reduce antihypertensive effects w/ NSAIDs (ASA, COX-2 inhibitors & non-selective NSAIDs). Risk of hypotension w/ thiazide or loop diuretics. Increased BP lowering w/ concomitant use of other antihypertensive. Reduction of antihypertensive effect w/ corticosteroid (systemic route).