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2011-07-21 13:19:10
Diuretic Agents

Diuretic Agents
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  1. Diuretic Agents
    • -Drugs that accelerate the rate of urine formation
    • -Result: removal of sodium and water
  2. Sodium
    • -Where sodium goes, water follows- 20% to 25% of all sodium is reabsorbed into the bloodstream in the loop of henle, 5%to 10% in the distal tubules, 3% in collecting ducts
    • -If water is not absorbed, it is excreted as urine
  3. The nephron and diuretic sites of action
  4. Diuretic Agents
    • -Carbonic anhydrase inhibitors
    • -Loop diuretics
    • -Osmotic diuretics
    • -Potassium-sparing diuretics
    • -Thiazide and thiazide-like diuretics
  5. Carbonic Anhydrase Inhibitors (CAIs)
    -acetazolamide (Diamox)
  6. Carbonic Anhydrase Inhibitors: Mechanism of Action
    • -The enzyme carbonic anhydrase helps to make H+ ions available for exchange with sodium and water in the proximal tubules
    • -CAIs block the action of carbonic anyhydrase, thus preventing the exchange of H+ ions with sodium and water
    • -Inhibition of carbonic anhydrase reduces H+ ion concentration in renal tubules
    • -As a result, there is increased excretion of bicarbonate, sodium, water and potassium
    • -Resorption of water is decreased and urine volume is increased
  7. Carbonic Anhydrase Inhibitors: Indications
    • -Adjunct agents in the long-term management of open-angle glaucoma
    • -Used with miotics to lower intraocular pressure before ocular surgery in certain cases
    • -Also useful in the treatment of- Glaucoma, Edema, Epilepsy, High-altitude sickness
    • -Acetazolamide is used in the management of edema secondary to HF when other diuretics are not effective
    • -CAIs are less potent diuretics than loop diuretics or thiazides-the metabolic acidosis they induce reduces their diuretic effect in 2 to 4 days.
  8. Carbonic Anhydrase Inhibitors: Side effects
    • -Metabolic acidosis -Paresthesias
    • -Anorexia -Urticaria
    • -Hematuria -Melena
    • -Photosensitivity
    • -Drowsiness
  9. Loop Diuretics
    • -furisemide (Lasix)
    • -bumetanide (Bumex)
    • -ethacrynic acid (Edecrin)
  10. Loop Diuretics: Mechanism of action
    • -Act directly on the ascending limb of the loop of Henle to inhibit sodium and chloride resorption
    • -Increase renal prostaglandins, resulting in the dilation of blood vessels and reduced peripheral vascular resistance
  11. Loop Diuretics: Drug effects
    • -Potent diuresis and subsequent loss of fluid
    • -Decreased fluid volume causes- Reduced BP, reduced pulmonary vascular resistance, reduced systemic vascular resistance, reduced central venous pressure, reduced left ventricular end-disastolic pressure
    • -Potassium depletion
  12. Loop Diuretics: Indications
    • -Edema associated with HF or hepatic or renal disease
    • -Control of hypertension
    • -Increase renal excretion of calcium in patients with hypercalcemia
  13. Loop Diuretic: Side effects
    Body system -Effect

    • CNS - Dizziness, headache, tinnitus, blurred vision
    • GI- Nausea, vomiting, diarrhea
    • Hematologic- Agranulocytosis, neutropenia, thrombocytopenia
    • Metabolic- Hypokalemia, hyperglycemia, hyperuricemia
  14. Loop Diuretics : Monitoring
    • -Electrolytes
    • -Volume status
    • -BUN/SCr
  15. Osmotic Diuretics
    -mannitol (Osmitrol)
  16. Osmotic Diuretics: Mechanism of Action
    • -Work in the proximal tubule
    • -Nonabsorabable, producing an osmotic effect
    • -Pull water into the blood vessels and nephrons from the surrounding tissues
  17. Osmotic Diuretics: Drug effects
    • -Reduced cellular edema
    • -Increased urine production, causing diuresis
    • -Rapid excretion of water, sodium, and other electrolyes, as well as excretion of toxic substances from the kidney
    • -Reduced excessive intraocular pressure
  18. Osmotic Diuretics: Indications
    • -Used in the treatment of patients in the early, oliguric phase of ARF
    • -To promote the excretion of toxic substances
    • -Reduction of intracranial pressure
    • -Treatment of cerebral edema
  19. Osmotic Diuretics: Side effects
    • -Convulsions
    • -Thrombophlebitis
    • -Pulmonary congestion
    • -Also headache, chest pain, tachycardia, blurred vision, chills, and fever
  20. Potassium-Sparing Diuretics
    • -amiloride (Midamor)
    • -triamterene (Dyrenium)
    • -spironolactone (aldactone)
    • -eplerenone (Inspra)
  21. Potassium-Sparing Duretics: Mechanism of Action
    • -Work in collecting ducts and distal convoluted tubules
    • -Intefere with sodium-potassium exchange
    • -Competitively bind to aldosterone receptors
    • -Block the resorption of sodium and water usually induced by aldosterone
  22. Potassium-Sparing Diuretics: Drug Effects
    • -Prevent potassium from being pumped into the tubule, thus preventing its secretion
    • -Competitively block the aldosterone receptors and inhibit its action
    • -The excretion of sodium and water is promoted
  23. Potassium-sparing Diuretics: Indication
    • -spironolactone and triamterene-Hyperaldosteronism, hypertension, reversing the potassium loss caused by potassium-losing drugs
    • -amiloride- treatment of HF
  24. Potassium-sparing diuretics: Side effects
    -spironolactone- gynecomastia, amenorrhea, irregular menses, postmenopausal bleeding

    -eplenerone- less gynecomastia, expensive
  25. Thiazide and Thiazide-like Diuretics
    • -Thiazide diurectics- hydrochlorothiazide (Esidrix, HydroDIURIL), chlorothiazide (Diuril), trichloromethiazide (Metahydrin)
    • -Thiazide-like diuretics- chlorthalidone (Hygroton), metolazone (Mykrox, Zaroxolyn)
  26. Thiazide and Thiazide-like Diuretics : Mechanism of action
    • -Inhibit tubular resorption of sodium and chloride ions
    • -Action primarily in the ascendnig loop of Henle and early distal tubule
    • -Result: water, sodium, and chloride are excredted
    • -Potassium is also excreted to a lesser extent
    • -Dilate the arterioles by direct relaxation
  27. Thiazide and Thiazide-like Diuretics: Drug effects
    • -Lowered peripheral vascular resistance
    • -Depletion of sodium and water
  28. Thiazide and Thiazide-like Diuretics: Indications
    • Hypertension ( one of the most prescribed group of agents for this)
    • -Edematous states
    • -Idiopathic hypercalciuria
    • -Diabetes insipidus
    • -adjunct agents in treatment of HF, hepatic cirrhosis
  29. Thiazide and Thiazide-like Diuretics: Side effects
    • Body system - Effect
    • -CNS- dizziness, headache, blurred vision, paresthesias, decreased libido
    • -GI- Anorexia, nausea, vomiting, diarrhea
    • -GU- Impotence
    • -Inegumentary- Urticaria, photosensitivity
    • -Metabolic- Hypokalemia, glycosuria, hyperglycemia
  30. Thiazide Diuretics
    • -Monitoring: - Electrolyes, BUN/SCr
    • -Advantages: -Safe, cheap, daily dosing, less side effects
  31. Nursing Implications
    • -Perform a thorough patient history and physical examination
    • -Asses baseline fluid volume status, intake and output, serum electrolyte values, weight, and vital signs-especially postural BPs
    • -Assess for disorders that may contraindicate or necessitate cautious use of these agents
    • -Instruct patients to take in the morning as much as possible to avoid interference with sleep patterns
    • -Monitor serum potassium levels during therapy
    • -Potassium supplements are usually not recommended when potassium levels exceed #mEq/L
    • -Teach patient to mantain proper nutrional and fluid volume status
    • -Teac patients to eat more potassium-rich foods when takin any but the potassium-sparing agents
    • -Foods high in potassium include bananas, oranges, dates, raisins, plums, fresh vegetables, potatoes, meat, and fish
    • -Patients taking diuretics alone with a digitalis preparation should be taught to monitor for digitalis toxicity
    • -Diabetic patients who are taking thiazide and/ or loop diuretics should be told to monitor blood glucose and watch for elevated levels
    • -Teach patients to change positions slowly, and to rise slowly after sitting or lying to prevent dizziness and possible fainting related to orthostatic hypotension
    • -Encourage patients to keep a log of their daily weight
    • -Encourage patients to return for follow-up visits and lab work
    • -Patients who have been ill with nausea, vomiting, and/or diarrhea should notify their physician because fluid loss may be dangerous
    • -Signs and symptoms of hypokalemia include muscle weakness, constipation, irregular pulse rate, and overall feeling of lethargy
    • -Instruct patients to notify physician immediately if they experience rapid heart rates or syncope ( reflects hypotension or fluid loss)
    • -A weight gain of 2 or more lbs a day or 5 or more lbs in a week should be reported immediately
    • -Excessive consumption of licorice can lead to an additive hyppokalemia in patients taking thiazides
    • -Monitor for adverse side effects: Metabolic alkalosis, drowsiness, lethargy, hypokalemia, tachycardia, hypotension, leg cramps, restlessness, decreased mental alertness
    • -Monitor for theraputic effects- Reduction in edema, fluid volume overload, HF, reduction of hypertension, return to norma intraocular pressure