Diuretics are drugs that increase the volume of urine produced by promoting the excretion of salt and water from the kidneys. There are several types of diuretics, each working in a distinct way.
Thiazide diuretics inhibit sodium re-absorption at the beginning of the distal convoluted tubules. Potassium sparing diuretics prevent excessive loss of potassium at the distal convoluted tubules.
A combination of a potassium sparing diuretic with a thiazide diuretic is used to reduce edema due to salt and water retention in disorders of the heart, kidneys, liver or lungs. They are used commonly in treatment of hypertension.