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What is a Diuretic?

IVSAT 2024

Diuretic Definition: Any substance which causes diuresis, or raised urine output, is referred to as a diuretic. This involves diuretics that are coerced. The diuretic definition tells that they are divided into many groups. Each class of diuretics works in a different way to increase water excretion from the body. An antidiuretic, including vasopressin, is a substance that decreases the amount of water excreted in the urine.

Diuresis Medical Definition: Diuresis is a disorder wherein the kidneys remove an excessive amount of fluid from the body. This raises the urine output and the number of times you need to go to the toilet.

History of Diuretic Drugs

The History of diuretic drugs started in 1919, a medical university student of Vienna discovered that mercurial injections successfully excreted water in syphilitic patients. Despite their toxicity, such drugs were widely considered the best tool in the fight against edoema for decades. Specialized and sophisticated experiments were only performed by the end of World war II, and then it was proven that sulfonamide derivatives have diuretic qualities. As a result, acetazolamide, a carbonic anhydrase inhibitor, was introduced in 1950.

After a team of researchers synthesised chlorothiazide, which revolutionised the diagnosis of cardiac edoema and hypertension, the current age of diuretics began several years later. Furosemide, a prototype of loop diuretics, was invented 50 years ago, in 1964. Furosemide acts on the huge segment of the Henle loop, causing a large diuresis of liquid, chlorine and sodium, demonstrating its utility even in cardiological crises including acute pulmonary edoema. In 1919, a medical student at the University of Vienna discovered which mercurial injections successfully excreted water in syphilitic patients.

Despite their toxicity, such drugs are considered the strongest tool in the fight against edoema for decades. Highly specialised and sophisticated experiments have only been performed by the end of WWII, but it was then proven that sulfonamide derivatives have diuretic properties. As a result, acetazolamide, a carbonic anhydrase inhibitor, was introduced in 1950.


1. High Ceiling/Loop Diuretic:

High-ceiling diuretics can cause significant diuresis, approximately around 20% of the purified NaCl (salt) and water load. When compared to natural renal sodium reabsorption, which retains just about 0.4 percent of filtered sodium in the urine, this is a significant difference. Since loop diuretics had the property, they are sometimes referred to as high-ceiling diuretics.

Loop diuretics, including furosemide, prevent the body from reabsorbing sodium just at the ascending loop of the nephron, resulting in the excretion of water throughout the urine, while sodium usually accompanies water back further into the extracellular fluid. Ethacrynic acid and torasemide are two major high-ceiling loop diuretics.

2. Thiazides:

Water is retained in the urine when thiazide-type diuretics, including hydrochlorothiazide, operate on the distal convoluted tubule and suppress the sodium-chloride symporter since water typically precedes penetrating solutes. 

The elevated water loss which has not been removed from the body as a consequence of a concurrent relationship including sodium loss from the convoluted tubule causes frequent urination. Thiazides have a short-term antihypertensive effect since they lower preload, which lowers blood pressure. The elongated effect, on the second hand, is because of an unexplained vasodilator influence that lowers blood pressure by lowering resistance.

3. Carbonic Anhydrase Inhibitors:

Carbonic anhydrase inhibitors stop the carbonic anhydrase enzyme from working in the proximal convoluted tubule. This has a number of consequences, such as bicarbonate build-up throughout the urine and reduced-sodium absorption. Acetazolamide and methazolamide are two drugs in this class.

4. Potassium-Sparing Diuretics:

They are diuretics that do not cause potassium to be secreted into the urine; as a result, potassium is preserved rather than lost more than in certain diuretics. Despite the fact that the word "potassium-sparing" belongs to an impact instead of a process or a position, it often applies to two distinct groups which have similar effects in similar places:

Aldosterone antagonists include spironolactone, an aldosterone competitive antagonist. Aldosterone introduces sodium channels to the collecting duct's principal cells and the nephron's late distal tubule. Spironolactone inhibits the entry of aldosterone into the principal cells, avoiding sodium reabsorption. Potassium canrenoate and Eplerenone are related agents. 

Amiloride and triamterene are sodium channel blockers for epithelial cells.

5. Calcium-Sparing Diuretics:

The word "calcium-sparing diuretic" is often used to describe drugs that cause a reduced percentage of calcium excretion.

The elevated level of calcium in serum may be caused by a lower calcium concentration in the urine. In hypocalcemia, the calcium sparing impact can be helpful, but in hypercalcemia, it can be harmful. Calcium-sparing diuretics include potassium-sparing and the thiazides diuretics.

The thiazides reduce the amount of calcium that has been lost in the urine.

While potassium-sparing diuretics raise calcium loss in urine, the rise is so much lower than that in certain other diuretic groups.

6. Osmotic Diuretics:

Osmotic diuretics (such as mannitol) enhance osmolarity while having low tubular epithelial cell permeability. They function by raising the flow of the blood to the kidney, especially the peritubular capillaries, by widening plasma volume and extracellular fluid. This lowers medullary osmolality, which lowers urine concentration in the Henle circle. Besides that, the restricted permeability of tubular epithelial cells raises the osmolality and therefore fluid retention in the filtrate.

7. Low Ceiling Diuretics:

A diuretic with a quickly straightening dose-effect curve is referred to as a "low ceiling diuretic". Some diuretic groups, including the thiazides, fall into this group.

Medical Uses

As the Diuretic meaning says, it has many medical uses:-

  • Heart failure, water poisoning, influenza, hypertension, liver cirrhosis, and certain other kidney disorders are all treated with diuretic substances in medicine

  • Some diuretics, including acetazolamide, aid to alkalize the urine, which assists in the excretion of substances like aspirin in situations of overdose or toxicity.

  • People with eating disorders, particularly those suffering from bulimia nervosa, can misuse diuretics in order to lose weight.

  • Few diuretic substances (particularly loop and thiazides diuretics) have antihypertensive effects that are exclusive of their diuretic effect. Thus, the decrease in blood pressure occurs by other pathways and at smaller concentrations than those needed to cause diuresis, rather than due to reduced blood volume mostly as a result of increased urine output.

  • Indapamide was developed solely for that purpose, and it has a wider therapeutic window for hypertension (without significant diuresis) than many other diuretics.

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FAQs on Diuretic

1. What Happens If Diuretics are No Longer Effective?

Ans. In patients having advanced HF, diuretic resistance is a major issue. Inability to alleviate congestive symptoms contributes to more hospitalizations, higher healthcare costs,  emergency room visits, and a lower quality of life.

2. Name Some Fruit That Acts as a Diuretics Examples.

Ans. Eating strawberries, celery, watermelon, other varieties of melon, cherries, apples, grapefruit, oranges, and plenty of leafy greens are some fruit/substances that act as diuretics examples.

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