Diuretics: Types and Mechanisms

Study Notes

Diuretics: Types, Mechanisms & Considerations

Loop Diuretics:
- Examples: Furosemide (Lasix), bumetanide
- Mechanism: Work in the loop of Henle, blocking sodium, chloride, and water reabsorption.
- Monitoring:
  - Hypokalemia: Can cause muscle cramps, weakness, and arrhythmias. Replace potassium through supplements or diet.
  - Dehydration: Encourage fluid intake.
  - Ototoxicity: Potential risk with high doses or rapid administration.
- Side Effects: Hypokalemia, dehydration, hypotension, hyperuricemia (risk of gout), ototoxicity.
- Contraindications: Severe electrolyte imbalances, anuria, severe renal failure.
- Nursing Considerations: Closely monitor potassium levels, encourage high-potassium foods (bananas, oranges, spinach).
Thiazide Diuretics:
- Examples: Hydrochlorothiazide (HCTZ), chlorthalidone.
- Mechanism: Act on the distal convoluted tubule, blocking sodium and water reabsorption.
- Monitoring:
  - Hypokalemia: Can cause low potassium levels. Encourage high-potassium foods.
  - Hyperglycemia: Monitor blood glucose, especially in diabetic patients.
- Side Effects: Hypokalemia, hyperglycemia, hypercalcemia, hyperuricemia.
- Contraindications: Severe renal impairment, known hypersensitivity.
- Nursing Considerations: Monitor electrolytes, especially potassium and sodium. Encourage fluid intake.
Potassium-Sparing Diuretics:
- Examples: Spironolactone, eplerenone.
- Mechanism: Block aldosterone's effects, leading to sodium and water excretion but potassium retention.
- Monitoring:
  - Hyperkalemia: Can cause arrhythmias.
- Side Effects: Hyperkalemia, gynecomastia (with spironolactone), menstrual irregularities, impotence.
- Contraindications: Hyperkalemia, severe renal failure, Addison's disease.
- Nursing Considerations: Avoid potassium supplements and limit high-potassium foods (bananas, oranges) while taking these diuretics.

High Potassium Foods

Bananas, oranges, spinach, potatoes, tomatoes, avocados, raisins, beans, nuts.

ACE Inhibitors

Examples: Lisinopril, enalapril, captopril (end in "-pril").
Mechanism: Inhibit the conversion of angiotensin I to angiotensin II, reducing vasoconstriction and blood pressure.
Side Effects:
- Persistent dry cough
- Angioedema: Rare but life-threatening swelling of the face, lips, or throat.
- Hyperkalemia
- Hypotension: Especially after the first dose.
Contraindications: Pregnancy, history of angioedema, severe renal impairment.
Monitoring: Blood pressure, potassium levels, renal function.
Nursing Consideration: Discontinue medication immediately if persistent cough or angioedema occurs.

Beta Blockers

Examples: Metoprolol, atenolol (end in "-olol").
Mechanism: Block beta-adrenergic receptors, lowering heart rate and contractility to decrease blood pressure.
Side Effects:
- Bradycardia: Low heart rate.
- Fatigue: Due to reduced cardiac output.
- Bronchospasm: Especially in patients with asthma or COPD.
- Masking of Hypoglycemia: Can hide symptoms of hypoglycemia in diabetic patients.
Contraindications: Asthma, COPD, heart failure, bradycardia, certain heart blocks.
Nursing Considerations: Monitor heart rate and blood pressure before administration. Avoid giving to patients with asthma or COPD.

Calcium Channel Blockers

Examples: Amlodipine, diltiazem, verapamil.
Mechanism: Block calcium channels in smooth muscle cells, leading to vasodilation and lower blood pressure.
Side Effects:
- Peripheral edema: Swelling of the extremities.
- Headache: Often a common side effect.
- Dizziness: May occur due to vasodilation.
Contraindications: Severe heart failure, certain heart blocks, and some specific types of patients.
Nursing Considerations: Encourage fluid intake and monitor fluid status, especially for patients with heart failure.