Makindo Medical Notes

Related Subjects: |Beta Blockers |Calcium Channel Blockers |Corticosteroids |Nitrates |Diuretics |Antiarrhythmic agents |Biological Agents |Chemotherapy Agents |Antimicrobials

Mode of Action

• Diuretics work by increasing the excretion of water and electrolytes from the kidneys, thereby reducing fluid volume in the body.
• They act at different parts of the nephron (the functional unit of the kidney) to inhibit the reabsorption of sodium and water.
• This results in a decrease in blood volume, which can lower blood pressure and reduce edema in conditions of fluid overload.

Indications

• Hypertension: Diuretics are commonly used to reduce blood pressure by decreasing blood volume.
• Heart Failure: They help to relieve symptoms of fluid overload, such as oedema and shortness of breath.
• Oedema: Diuretics are used to reduce swelling caused by kidney, liver, or heart disease.
• Kidney Stones: Certain diuretics, like thiazides, reduce calcium excretion and may help prevent the formation of calcium-containing stones.
• Cerebral Oedema: Osmotic diuretics like mannitol are used to reduce intracranial pressure in cases of brain injury or swelling.

Types of Diuretics

• Thiazide Diuretics: Primarily used for hypertension. They act on the distal convoluted tubule to inhibit sodium reabsorption. Examples include hydrochlorothiazide and chlorthalidone.
• Loop Diuretics: Highly potent and often used in heart failure. They act on the loop of Henle to inhibit sodium and chloride reabsorption. Examples include furosemide and bumetanide.
• Potassium-Sparing Diuretics: Help conserve potassium, often used in combination with other diuretics to prevent hypokalemia. Examples include spironolactone and amiloride.
• Osmotic Diuretics: Used to reduce intracranial and intraocular pressure. They act by creating an osmotic gradient that pulls water into the urine. Example: mannitol.
• Carbonic Anhydrase Inhibitors: Mainly used to reduce intraocular pressure in glaucoma. Example: acetazolamide.

Delivery Forms

• Oral: Most diuretics are taken by mouth, typically for chronic conditions like hypertension and heart failure.
• Intravenous (IV): Used in hospital settings for acute situations, such as pulmonary edema or severe hypertension.

Side Effects

• Electrolyte Imbalance: Diuretics can cause imbalances in electrolytes like potassium, sodium, and magnesium, potentially leading to hypokalemia or hyperkalemia.
• Dehydration: Excessive fluid loss can lead to dehydration, especially with potent loop diuretics.
• Hypotension: Blood pressure can drop too low, causing dizziness and fainting, particularly when standing up.
• Gout: Thiazide and loop diuretics can raise uric acid levels, potentially triggering gout attacks.
• Kidney Function: High doses, especially of loop diuretics, can impair kidney function.

More details

Drug Interactions

• NSAIDs: Nonsteroidal anti-inflammatory drugs can reduce the effectiveness of diuretics, especially in patients with heart failure.
• ACE Inhibitors and ARBs: Combined use with potassium-sparing diuretics can increase the risk of hyperkalemia.
• Digoxin: Diuretic-induced hypokalemia can increase the risk of digoxin toxicity.
• Lithium: Diuretics can increase lithium levels, raising the risk of toxicity.

Monitoring and Precautions

• Monitor electrolyte levels, especially potassium and sodium, to detect and manage imbalances early.
• Check blood pressure regularly, as diuretics can cause hypotension, especially in elderly patients.
• Assess kidney function periodically, particularly in patients taking high doses or using potent diuretics like furosemide.

Patient Education

• Instruct patients to take diuretics in the morning to prevent nocturia (frequent nighttime urination).
• Encourage a low-sodium diet to help improve the effectiveness of diuretic therapy.
• Advise patients to report any symptoms of dehydration, dizziness, or muscle cramps, which could indicate electrolyte imbalance.
• Explain the importance of regular blood tests to monitor electrolyte levels and kidney function.

Common Diuretics: Names, Doses, and Indications