Diuretics: Mechanism of Action and Applications

Diuretics: Mechanism of Action and Applications

I. Diuretics

Diuretics are a group of medications that act on the kidneys to increase urine output, helping to treat medical conditions related to fluid and salt retention in the body such as edema, hypertension, and heart failure.

1. Classification:

• Carbonic Anhydrase Inhibitors (CAIs):

• Representative: Acetazolamide.

• Site of action: Proximal convoluted tubule.

• Loop Diuretics:

• Representative: Furosemide, Bumetanide.

• Site of action: Ascending limb of the loop of Henle.

• Osmotic Diuretics:

• Site of action: Descending limb of the loop of Henle.

• Thiazide Diuretics:

• Representative: Fludex (Indapamide), Hygroton (Chlorthalidone), Chronexan (Xipamide).

• Site of action: Early distal convoluted tubule.

• Potassium-sparing Diuretics (Non-aldosterone antagonists):

• Representative: Triamteren (Teriam), Amiloride (Modamid).

• Potassium-sparing Diuretics (Aldosterone antagonists):

• Representative: Spironolactone (Aldacton).

2. Mechanism of Action:

• CAIs: Inhibit the carbonic anhydrase enzyme, reducing sodium and water reabsorption, leading to diuresis.

• Loop Diuretics: Inhibit sodium and chloride reabsorption in the ascending limb of the loop of Henle, leading to powerful diuresis.

• Osmotic Diuretics: Increase the osmotic pressure of the fluid in the lumen of the renal tubules, inhibiting water and salt reabsorption, leading to diuresis.

• Thiazide Diuretics: Inhibit sodium and chloride reabsorption in the early distal convoluted tubule, leading to mild diuresis.

• Potassium-sparing Diuretics:

• Triamteren, Amiloride: Inhibit the sodium channel in the distal convoluted tubule, reducing sodium reabsorption and also decreasing potassium and hydrogen excretion.

• Spironolactone: An aldosterone antagonist, inhibiting the action of aldosterone at the receptor in the distal convoluted tubule, leading to reduced sodium reabsorption and increased potassium excretion.

3. Side Effects:

• Thiazide:

• Increased blood uric acid, worsening gout.

• Decreased calcium excretion, which can prevent kidney stones.

• Worsening of type 2 diabetes.

• Reduced effectiveness of anticoagulants, gout medications, and insulin.

• Increased effectiveness of anesthetics, cardiac glycosides, loop diuretics, and vitamin D.

• Hypokalemia when used with NSAIDs, Amphotericin B, and corticosteroids.

• Potassium-sparing Diuretics:

• Spironolactone: Can cause gynecomastia in men, hirsutism, and menstrual irregularities.

4. Other Effects:

• Thiazide: Increases calcium and magnesium excretion, used to treat symptomatic hypercalcemia.

• Potassium-sparing Diuretics: Helps retain potassium in the body, used in the treatment of hypokalemia.

II. Antidiuretic Hormones:

• ADH (Antidiuretic hormone): A polypeptide hormone from the posterior pituitary gland, has antidiuretic (anti-polyuria) effects.

• Drugs belonging to the group of antidiuretic hormones: Desmopressin, Vasopressin, Lypressin, Argipressin.

III. Notes:

• Use diuretics only as prescribed by your doctor.

• Carefully monitor side effects, especially hypokalemia.

• Drink plenty of fluids while taking diuretics.

IV. Conclusion:

Diuretics are an important group of medications in the treatment of medical conditions related to fluid and salt retention in the body. Choosing the right type of diuretic and carefully monitoring side effects are crucial to achieving optimal therapeutic outcomes.