Diuretics and Antidiuretics

Diuretics and Antidiuretics


difference between diuretics and antidiuretics

The renal system consists mainly of two types of drugs – Diuretics and Antidiuretics. Diuretics drugs are useful to increase urine output. Antidiuretic drugs are useful to decrease urine output. Normal urine output = 1.5 liter / day.

Physiology of urine production

  • Urine = { glomerular filtration + tubular secretion } – tubular reabsorption
  • Normal GFR – 180 liter / day and 125 ml / minute.
  • Sometimes, diuretic increases the urine output by decreasing tubular reabsorption, via inhibiting the various symport, antiport, and cotransport in the renal tubules.

Diuretics Drugs

Diuretics drugs

The diuretics drugs are useful to treat patients, who are suffering from water and sodium chloride retention. The drug increases the excretion of sodium and water in urine or increases urine output.

lasix injection uses

Generally, Furosemide should be administered intravenously. Intramuscular administration must be restricted to exceptional cases where neither oral nor intravenous administration is feasible. Lasix Injection belongs to a group of medicines called diuretics. It is used for the emergency treatment of very high blood pressure (hypertensive emergency), as it reduces the blood pressure immediately. It also rapidly reduces the swelling (edema) caused by too much water in the body


  • Natriuretic – Drugs cause the excessive loss of sodium in the urine.
  • Kaliuresis – Drugs cause the net loss of potassium in the urine.
  • Saluretics – Drugs cause the net loss of sodium and chloride in the urine.
  • Calciuretics – Drugs cause the net loss of calcium in the urine.
  • Potassium-sparing – It is also called Amiloride.
  • Drugs cause the retention of potassium and decrease loss of potassium in the urine.
  • Calci Saving – Drugs cause the retention of calcium and decrease the loss of calcium in the urine.

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Diuretics Classification with Examples

  1. High efficacy diuretics
  • Also called Loop diuretics.
  • Drugs – furosemide
    • Torasemide
    • Bumetanide.
  1. Medium efficacy diuretics
  • Thiazides – HCTZ
  • Theatres like – chlorthalidone
      • Metolazone
      • Xipamide.
  1. Weak efficacy diuretics
  • Also called the adjunctive diuretics.
  • Carbonic anhydrase inhibitor = acetazolamide
  • Potassium sparing diuretics = spironolactone

= Amiloride.

  • Osmotic diuretics = mannitol

= glycerol

= Isosorbide.

High efficacy diuretics

  • The loop diuretics act on the ascending loop of Henle and inhibit the Na+_K+_2cl- co – transport.
  • The drug increases the urine output due to decreased tubular reabsorption.
  • It is also known as high ceiling diuretics and most powerful diuretics.
  • The drug increased urine output up to 10 liter / day.
  • Furosemide drug – Also called lasix.
  • Suitable for acute use.
  • 40 mg – tablet form, 20 mg / ml in injection.
  • To stimulate the quick onset effects, and effective only for short duration ( 3 – 6 hours).

Torasemide drug-

In renal failure – Torsemide uses up to 100 mg.

In edema – use 5 – 20 mg.


  • useful in edema
  • 1 – 5 mg orally.

Uses of the high-efficacy drug

  • In the acute pulmonary edema.
  • Edema and cerebral edema.
  • Congestive cardiac failure (CCF)
  • Hypertension
  • Hypercalcemia and renal calcium stone
  • Acute renal failure.

Medium efficacy diuretics

The drug acts on the cortical diluting loop of Henle and the early portion of the distal convoluted tubule. The drug inhibits the sodium chloride simport and increases the urine output by decreasing tubular reabsorption. Thiazide – HCTZ (hydrochlorothiazide). Hydrochlorothiazide is the most commonly used drug in these groups. Dose = 12.5 – 100 mg tablet.

Thiazide like drug

  • Chlorthalidone – 50 – 100 mg dose.
      • Onset effective.
  • Metolazone – 5 – 20 mg dose.
      • Onset effective.
  • Xipamide – Dose 20 – 40 mg.
  • Thiazide and thiazide-like drugs are available in tablet forms and are suitable for chronic and long-term uses.

Uses of medium efficacy diuretics

  • Diabetic insipidus
  • 1st line drug of hypertension
  • To maintain the edema
  • Hypercalcemia and recurrent calcium stone.
  • Weak efficacy diuretics – Also called the adjunctive diuretics.
  • Carbonic anhydrase inhibitor
  • Eg:- Acetazolamide
  • The drug acts on the proximal tubules and inhibits the carbonic anhydrase.
  • Dose 250 mg OD / BD.
  • Drug uses
    • Glaucoma
    • Gastric and duodenal ulcer
    • Antiepileptic
    • In acute mountain sickness
    • Neurological disorder
    • Hypertension

medium efficacy diuretics Adverse effects

  • Fever, rashes, fatigue.
  • Acidosis, hypokalemia.
  • Abdominal discomfort.
  • Acetazolamide is contraindicated in liver disease.
  1. Potassium-sparing diuretics

  • Drug = Spironolactone.
  • The spironolactone is an aldosterone antagonist.
  • The drug increases the excretion of sodium and water without producing appreciable potassium loss.
  • It acts on the sodium potassium antiport and retains the potassium and excrete the sodium.
  • Spironolactone Dose = 25 – 50 mg BD.

Uses of Potassium-sparing diuretics

  • Nephrotic and cirrhotic edema.
  • Congestive heart failure (CHF)
  • Hypertension
  • To prevent the potassium loss
  • Primary aldosteronism.

Adverse effects of Potassium-sparing diuretics

  • Hyperkalemia, metabolic acidosis
  • Drowsiness, confusion, skin rashes
  • Abdominal upset
  • Gynecomastia
  • Menstrual irregular disorder.
  1. Osmotic diuretics

  • Mannitol – It is the most common osmotic diuretics.
  • Mannitol is a polyhydric alcohol.
  • It consists of low molecular weight, nonelectrolyte and freely filters through the glomerulus.
  • Mannitol dose = 100 ml, 350 ml Iv infusion.
  • 10 – 20 % solution of mannitol.

Uses of mannitol

  • To reduce the intraocular pressure (IOP) in glaucoma.
  •  In head injury, to decrease the intracranial pressure (ICP).
  • To maintain the glomerular filtration (GFR) and urine flow.
  • To prevent renal failure.

Contraindication of mannitol

  • Pulmonary edema, anuria
  • Cerebral hemorrhage
  • Congestive heart failure.

Adverse effects of mannitol  – Nausea, vomiting, dehydration, headache, pulmonary edema, hypotension.

Key Points of diuretics

  1. Which drug is useful to increase the urine output – Diuretic
  2. High efficacy diuretics is called – Loop diuretics
  3. Most common osmotic diuretic is – Mannitol
  4. Loss of sodium and chloride with urine – Saluretics
  5. Excessive loss of sodium with urine is called – Natriuretics
  6. Weak efficacy diuretics is called – Adjunctive diuretics
  7. Most powerful diuretic is – Loop diuretics
  8. Which diuretic drug is called Lasix – Furosemide
  9. Most common useful drug in medium efficacy diuretics – Hydrochlorothiazides
  10. Common potassium-sparing diuretics is – Spironolactone
  11. Which diuretic is useful to reduce IOP and ICP – Mannitol
  12. Synthetic analog of vasopressin – Desmopressin
  13. Which drug acts on the V1 receptor of ADH – Vasopressin

Antidiuretic drugs

  • It is a substance that inhibits water excretion without affecting the sodium excretion.
  • The drugs useful to reduce urine output.
  • The drugs mostly used in the diabetes insipidus.
  • Antidiuretic hormone (ADH) is secret from the posterior pituitary gland.
  • ADH hormone water reabsorption from distal and collecting tubules, and reduced urine output.
  • ADH stimulated due to increased plasma osmolarity contraction of extracellular fluid volume.
  • ADH consists of the V1 and V2 receptors.

Antidiuretic drugs list

  • Antidiuretics drugs
  • Antidiuretic hormone – Desmopressin and vasopressin.
  • Thiazide diuretics – Amiloride.
  • Indomethacin, carbamazepine, chlorpropamide.
  1. Vasopressin –

Vasopressin acts on a V1 receptor of ADH that leads blood vessels contraction and increases the arterial pressure. Vasopressin also acts on V2 receptors and leads fluid reabsorption in the renal tubules and increases the water permeability, that result is decreased urine formation.

Vasopressin uses

  • Diabetic insipidus (DI)
  • Bleeding oesophageal varices
  • Hypotension and shock
  • Abdominal distension
  • Before abdominal radiography.

Vasopressin side effects

  • Water intoxication
  • Hyponatremia
  • Increase the specific gravity of urine.
  1. Desmopressin –

It is a synthetic analog of vasopressin, which is work on the V2 receptor. Desmopressin acts on the CD cells. Desmopressin is a man-made form of vasopressin. Desmopressin causes the antidiuretic effect that increases the water reabsorption, decreases water excretion.

Uses of Desmopressin

  • Nocturnal enuresis
  • To prevent dehydration
  • Diabetes insipidus
  • Haemophilia – A
  • Von willebrand disease.

Desmopressin Dose

  • Dose – 10 – 40 mg / day in adults.
  • 5 – 10 mcg / H. S. in children.

Adverse effects of Desmopressin –

Congestion, nasal irritation, epistaxis, hyponatremia etc.

  1. Thiazide (HCTZ) – Use to increase the tubular reabsorption in the. It is useful in both neurogenic and nephrogenic DI.
  2. Amiloride – It is a drug of choice (DOC) of lithium-induced nephrogenic DI.
  3. Indomethacin – Use as an antidiuretic, and treat the nephrogenic DI and nephrotic syndrome.
  4. Carbamazepine – It is used in the neurogenic DI.

Key points of Antidiuretics drugs

  1. Which drug is useful to decrease the urine output – Antidiuretic
  1. Normal urine output – 1.5 liter / day
  1. Normal GFR in a healthy person – 180 liter/day
  1. Antidiuretic hormone secret from the – Posterior pituitary gland
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