The 3 Classes of Diuretics and Their Primary Sites of Action in the Nephron

For Internal Use Only

Adapted from: Oparil S and Weber MA. Hypertension.Elsevier/Sanders 2nd ed. 2005; Lip G and Bakris G. Handbook Hypertension Management. CMG 2006

Thiazide Diuretics

• Duration of action of 12–24 hours• Blood pressure lowering effect with low doses• Additive blood pressure lowering effect when used in combination with

other antihypertensive drugs• Main side effects:

- hypokalemia- hyponatremia- hyperglycemia- altered plasma lipid concentration- hyperuricemia or gout- impotence (reversible on withdrawal of treatment)

Bendroflumethiazide 1.25-2.5 mg once dailyChlorthalidone 12.5-25 mg once dailyHydrochlorothiazide 12.5-25 mg once dailyIndapamide 2.5 mg once daily or 1.5 mg

of sustained release (SR) preparation

For Internal Use OnlyLip G and Bakris G. Handbook Hypertension Management. CMG 2006

Loop Diuretics

• Bumetanide 0.5 – 2 mg/d• Furosemide 20 – 80 mg/d• Torsemide 2.5 – 10 mg/d

• Most commonly used for powerful diuresis (renal failure, severe heart failure with oedema)

• Rapid onset of action:• - 1 hour after oral administration• - peak at 30 min after intravenous administration

• Useful when blood pressure require extremely rapid lowering (brisk diuresis)

• Main side effects:- Hypokalemia- hyponatremia

Lip G and Bakris G. Handbook Hypertension Management. CMG 2006

For Internal Use Only

Diuretics that Cause Potassium Retension

• Triamterene 50 - 100 mg/d

• Amiloride 5 – 10 mg/d

• Spironolactone 25 – 100 mg/d

• Weak diuretics

• Little effect on blood pressure

• Cause retention potassium

• Combined to thiazide or loop diuretics to prevent or remedy hypokalemia

• Main side effects:

- hyperkalemia

- hyponatremia

- rashes

Lip G and Bakris G. Handbook Hypertension Management. CMG 2006

For Internal Use Only