Triamterene is a potassium-sparing diuretic
Potassium-sparing diuretic
Potassium-sparing diuretics are diuretic drugs that do not promote the secretion of potassium into the urine.They are used as adjunctive therapy, together with other drugs, in the treatment of hypertension and management of congestive heart failure....

 used in combination with thiazide
Thiazide is a term used to describe a type of molecule and a class of diuretics often used to treat hypertension and edema ....

 diuretics for the treatment of hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...

 and edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...

Triamterene directly blocks the epithelial sodium channel
Epithelial sodium channel
The epithelial sodium channel is a membrane-bound ion-channel that is permeable for Li+-ions, protons and especially Na+-ions. It is a constitutively active ion-channel...

 (ENaC) on the lumen side of the kidney collecting tubule. Other diuretics cause a decrease in the sodium concentration of the forming urine due to the entry of sodium into the cell via the ENaC, and the concomitant exit of potassium from the principal cell into the forming urine.