Lecture on Loop Diuretics

Introduction

• Loop diuretics are very potent, causing rapid diuresis (fluid expulsion).
• Mechanism: Inhibits sodium and chloride reabsorption in the loop of Henle.

Mechanism of Action

• Reduces sodium, chloride, and water reabsorption, leading to decreased systemic vascular resistance.
• Results in potent diuresis and substantial fluid loss.

Therapeutic Effects

• Decreases blood pressure due to high volume diuresis.
• Used for high blood pressure and fluid overload conditions like edema and congestive heart failure (CHF).

Indications

• Prescribed for patients with high blood pressure.
• Helps in conditions of fluid overload, edema, CHF, hepatic or renal disease.

Precautions

• Be cautious in patients with impaired renal function.
• Must have some renal function for drug excretion.
• Avoid in patients with pre-existing dehydration or electrolyte disturbances like hypokalemia (low potassium).

Contraindications

• Chronic renal failure patients with anuria (low/no urine output).
• Untreated dehydration or electrolyte disturbances.
• Sulfa allergies as loop diuretics are chemically related to sulfonamide antibiotics.

Side and Adverse Effects

• Electrolyte disturbances, particularly hypokalemia (symptoms: leg cramps, tingling, numbness, nausea, vomiting, abdominal cramps).
• Dehydration, hypotension, dizziness due to volume depletion.

Nursing Actions

• Monitor blood pressure and input/output (I&O).
• Check electrolytes, with focus on potassium and magnesium levels.
• Monitor renal function (BUN and creatinine levels).
• Daily weight checks to monitor fluid volume status.
• Educate patients to change positions slowly due to risk of dizziness from blood pressure changes.

Key Drug Example

• Furosemide
  • Prototype loop diuretic.
  • Known for potent diuresis and common side effect of hypokalemia.
• Remember: Furosemide lowers potassium levels and is very potent.