Diuretics

Question 0

Name the thiazide diuretics.

Answer 0

Hydrochlorothiazide 
metolazone
chlorothiazide
chlorthalidone
indapamide

Question 1

What are diuretics?

Answer 1

Drugs inducing a state of increased urine production by the kidneys are called diuretics.

Question 2

What is the mechanism of Action of thiazide diuretics?

Answer 2

• They enter the nephron via the organic acid secretory pathway of the proximal tubule.
• They block the tubular reabsorption of Na+ at the early part of the distal convoluted tubule.
• All thiazide diuretics are considered equally effective. No synergy with double thiazide therapy.»where Na+ goes, water goes.

Question 3

what are the therapeutic uses of thiazide diuretics.

Answer 3

• treatment of hypertension. work better than loop diuretics in the treatment of chronic hypertension. why? They do not cause rebound vasoconstriction as the loops sometimes do. They also have mild vasodilating properties.
• Treatment of mild to moderate edema.

Question 4

What are the adverse effects of thiazide diuretics?

Answer 4

• Dehydration & electrolyte imbalance: Hypokalemia, hyponatremia, hypochloremia, hyperuricemia, & alkalosis. Patients should still drunk normal amounts of fluid to avoid dehydration.
• Hypokalemia Thiazides cause the kidneys to pull K+ into the urine. Bananas & fruits are a good dietary source of potassium. Some patients will take a KCl (potassium chloride) supplement like K-Dur or Micro-K
• Hyperuricemia (can produce gout attacks by blocking the elimination of uric acid)
• Large doses may cause hyperglycemia in diabetics.
• Orthostatic hypotension

Question 5

What drugs are included in the group loop diuretics?

Answer 5

“ide”
furosemide
bumetanide
torsemide

Question 6

What is the mechanism of action of loop diuretics.

Answer 6

• Block the Na+ reabsorption in the loop of the Henle.
• Act in the ascending limp of the loop of Henle. Loop of Henle is responsible for 25-30% of all Na+ reabsorption. This is why loop diuretics are the most powerful diuretics.
• Must enter the nephron via the organic acid pathway of the proximal tubule to be effective.
• Onset of Action: 30 minutes after an oral dose & 5 minutes after an IV dose.

Question 7

what are the therapeutic uses of Loop diuretics.

Answer 7

• Drugs of choice for edema associated with congestive heart failure or renal failure.
• Drugs of choice for acute pulmonary edema (fluid in the lungs)
• Treatment of hypertension. Thiazides actually work better for hypertension.

Question 8

what are the adverse effects of Loop diuretics?

Answer 8

• Orthostatic hypotension & dizziness, photosensitivity, rash, hyponatremia
• Dehydration, hypokalemia, & electrolyte imbalance (much more severe than with thiazides) Patients often will require supplemental K+ to avoid hypokalemia.
• Ototoxicity- hearing can be affected, especially if used in conjunction with aminoglycosides.
• Hyperuricemia & hyperglycemia in diabetics

Question 9

What is the dosing for loop diuretics?

Answer 9

• Once daily morning dosing is preferred. If the diuresis is adequate, but fluid returns too quickly, try twice daily dosing.
• Do NOT take diuretics before bedtime! Nocturnal awakenings can cause falls in elderly patients.
• Loop diuretics have synergy with thiazides. Metolazone (or any of the thiazides) may be used in conjunction with a loop diuretic to enhance diuresis in patients who do not respond adequately to large doses of the loop diuretics alone.

Question 10

What drugs are included in the group Potassium Sparing Diuretics?

Answer 10

sprionolactone
amiloride
eplerenone
triamterene

Question 11

What is the mechanism of action for spironolactone & eplerenone?

Answer 11

• Synthetic aldosterone antagonists. Compete with aldosterone at renal receptor sites.
• Aldosterone normally stimulates Na+ reabsorption K+ elimination at the distal tube.
• Thus they cause Na+ elimination and K+ reabsorption
• Na+ wasting & K+ retention

Question 12

what is the mechanism of action for amiloride & triamterene?

Answer 12

*Are NOT aldosterone antagonists. Act directly in the distal renal tubule to inhibit the Na+ reabsorption & K+ elimination that is normally stimulated by aldosterone.

Question 13

What are the therapeutic uses of Potassium sparing diuretics?

Answer 13

• Not a powerful enough diuretic to use alone.
• Used in combination with thiazides or loops to help retain K+ and prevent hypokalemia.
• Are useful in treating ascites associated with liver failure
• Spironolactone & eplerenone have been shown to reduce mortality in heart failure patients.

Question 14

What are the adverse effects of potassium sparing diuretics?

Answer 14

• Hyperkalemia. Can be life-threatening. Monitor K+ closely if using with ACE-I or ARB.
• Use extreme caution if giving K+ supplements to patients receiving potassium-sparing diuretics!
• Spironolactone, since it chemically resembles some sex steroids, may rarely cause gynecomastia in men and menstrual irregularities & deepening of voice in females.