Diuretics are medications that increase diuresis, that is urine production. Loop diuretics block the sodium-potassium-chloride transporter on the thick ascending limb of the loop of Henle, causing the excretion of these substances as well as water from the body. Thiazide diuretics act on distal convoluted tubules and inhibit sodium-chloride channels causing salt and water excretion.

What are loop diuretics?

Definition:

Loop diuretics are diuresis-causing medications that act on the loop of Henle in the nephrons.

Mechanism of action:

Loop diuretics block the sodium-potassium-chloride transporter on the thick ascending limb of the loop of Henle, causing the excretion of these substances as well as water from the body.

Examples:

Examples of loop diuretics are furosemide, torsemide, bumetanide, and ethacrynic acid. 

Uses:

Loop diuretics cause massive diuresis therefore they are used in conditions like heart failure and pulmonary edema.

Route of administration:

Loop diuretics can be given intravenously, intramuscularly, and orally.

Side effects:

Side effects of loop diuretics are hypotension, hyponatremia, hyperkalemia, hypomagnesemia, ototoxicity, and metabolic alkalosis.

Contraindications:

Loop diuretics should not be used in patients with preexisting electrolyte imbalance, renal failure, and hepatic encephalopathy. Also, these drugs should be used with caution in diabetic individuals.

What are Thiazide diuretics?

Definition:

Thiazide diuretics are diuretic medications that act on the distal convoluted tubule of the nephrons.

Mechanism of action:

Thiazide diuretics act on distal convoluted tubules and inhibit sodium-chloride channels causing salt and water excretion.

Examples:

Examples of thiazide diuretics are chlorothiazide and hydrochlorothiazide, whereas thiazide-like diuretics include chlorthalidone and indapamide.

Uses:

Thiazide diuretics are used as antihypertensives. They are less commonly given to patients with heart failure and pulmonary edema.

Route of administration:

Thiazide diuretics are given either per oral or intravenously.

Side effects:

Side effects of thiazide diuretics are hypercalcemia, hyperuricemia, hyponatremia, hypokalemia, hyperglycemia, hypercholesterolemia, and metabolic alkalosis.

Contraindications:

Thiazide diuretics should not be used in patients having diabetes mellitus, gout, hyperlipidemia, renal failure with anuria, and in those with sulfa toxicity.

Difference between Loop diuretics and Thiazide diuretics

Definition:

Loop diuretics are diuresis-causing medications that act on the loop of Henle in the nephrons. Thiazide diuretics are diuretic medications that act on the distal convoluted tubule of the nephrons.

Mechanism of action:

Loop diuretics block the sodium-potassium-chloride transporter on the thick ascending limb of the loop of Henle, causing the excretion of these substances as well as water from the body. Thiazide diuretics act on distal convoluted tubules and inhibit sodium-chloride channels causing salt and water excretion.

Examples:

Examples of loop diuretics are furosemide, torsemide, bumetanide, and ethacrynic acid. Examples of thiazide diuretics are chlorothiazide and hydrochlorothiazide, whereas thiazide-like diuretics include chlorthalidone and indapamide.

Uses:

Loop diuretics cause massive diuresis therefore they are used in conditions like heart failure and pulmonary edema. Thiazide diuretics are used as antihypertensives. They are less commonly given to patients with heart failure and pulmonary edema.

Route of administration:

Loop diuretics can be given intravenously, intramuscularly, and orally. Thiazide diuretics are given either per oral or intravenously.

Side effects:

Side effects of loop diuretics are hypotension, hyponatremia, hyperkalemia, hypomagnesemia, ototoxicity, and metabolic alkalosis. Side effects of thiazide diuretics are hypercalcemia, hyperuricemia, hyponatremia, hypokalemia, hyperglycemia, hypercholesterolemia, and metabolic alkalosis. 

Contraindications:

Loop diuretics should not be used in patients with preexisting electrolyte imbalance, renal failure, and hepatic encephalopathy. Also, these drugs should be used with caution in diabetic individuals. Thiazide diuretics should not be used in patients having diabetes mellitus, gout, hyperlipidemia, renal failure with anuria, and in those with sulfa toxicity.

Table of differences between Loop diuretics and Thiazide diuretics

FAQs

What is the difference between thiazide and furosemide?

Loop diuretics block the sodium-potassium-chloride transporter on the thick ascending limb of the loop of Henle, whereas thiazide diuretics act on distal convoluted tubule and inhibit sodium-chloride channels causing salt and water excretion.

Why are thiazides better than loop diuretics?

Thiazide diuretics are better antihypertensive drugs than loop diuretics. 

Are thiazides more effective than loop diuretics?

Yes, in hypertension thiazides are more effective than loop diuretics.

Why are loop diuretics preferred over thiazides in heart failure?

Because loop diuretics cause massive diuresis.

Why are loop diuretics more effective?

Because loop diuretics cause massive diuresis in edematous conditions.

What are the disadvantages of loop diuretics?

Disadvantages of loop diuretics are hypotension, hyponatremia, hyperkalemia, hypomagnesemia, ototoxicity, and metabolic alkalosis

When should you avoid loop diuretics?

Loop diuretics should not be used in patients with preexisting electrolyte imbalance, renal failure, and hepatic encephalopathy. Also, these drugs should be used with caution in diabetic individuals.

Why are loop diuretics not used in hypertension?

They do not have a good antihypertensive effect.

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