Antihypertensive Drug - Diuretics

Diuretics

Diuretics help the kidneys eliminate excess salt and water from the body's tissues and blood.

• Loop diuretics:
  • bumetanide
  • ethacrynic acid
  • furosemide
  • torsemide
• Thiazide diuretics:
  • epitizide
  • hydrochlorothiazide and chlorothiazide
  • bendroflumethiazide
• Thiazide-like diuretics:
  • indapamide
  • chlorthalidone
  • metolazone
• Potassium-sparing diuretics:
  • amiloride
  • triamterene
  • spironolactone

Only the thiazide and thiazide-like diuretics have good evidence of beneficial effects on important endpoints of hypertension, and hence, should usually be the first choice when selecting a diuretic to treat hypertension. The reason why thiazide-type diuretics are better than the others is (at least in part) thought to be because of their vasodilating properties. Although the diuretic effect of thiazides may be apparent shortly after administration, it takes longer (weeks of treatment) for the full anti-hypertensive effect to develop. In the United States, the JNC7 (The Seventh Report of the Joint National Committee on Prevention of Detection, Evaluation and Treatment of High Blood Pressure) recommends starting with a thiazide diuretic if single therapy is being initiated and another medication is not indicated. This is based on a slightly better outcome for chlortalidone in the ALLHAT study versus other anti-hypertensives and because thiazide diuretics are relatively cheap. A subsequent smaller study (ANBP2) published after the JNC7 did not show this small difference in outcome and actually showed a slightly better outcome for ACE-inhibitors in older male patients.

Despite thiazides being cheap, effective, and recommended as the best first-line drug for hypertension by many experts, they are not prescribed as often as some newer drugs. This is because they have been associated with increased risk of new-onset diabetes and as such are recommended for use in patients over 65 where the risk of new-onset diabetes is outweighed by the benefits of controlling systolic blood pressure. Another theory is that they are off-patent and thus rarely promoted by the drug industry.