All of the following drugs acts as potassium sparing diuretics, EXCEPT:

Potassium-sparing diuretics prevent K+ secretion by antagonizing the effects of aldosterone at the late distal and coical collecting tubules. Inhibition may occur by direct pharmacologic antagonism of mineralocoicoid receptors (spironolactone, eplerenone) or by inhibition of Na+ influx through ion channels in the luminal membrane (amiloride, triamterene). Ref: Katzung, 11th edition, Chapter 15.