1. Cardiovascular & Renal System
Diuretics
Lilley Reading & Workbook, Chap 25

2. Diuretics Drugs that accelerate the rate of urine formation
In the nephron, where sodium goes, water follows
20% to 25% of all sodium is reabsorbed into the bloodstream in the ascending loop of Henle
5% to 10% in the distal convoluted tubules
3% in collecting ducts
If water is not absorbed, it is excreted as urine
Result: removal of sodium and water

3. Diuretics

4. Diuretic Drugs Classifications
Carbonic anhydrase inhibitors
Loop diuretics
Osmotic diuretics
Potassium-sparing diuretics
Thiazide and thiazide-like diuretics

5. Diuretics Carbonic Anhydrase Inhibitors (CAI) 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 anhydrase,
thus preventing the exchange of H+ ions with sodium and water
reduces H+ ion concentration in renal tubules
Result:
increased excretion of bicarbonate, sodium, water, & K+
Resorption of water is decreased and urine volume is increased

6. Diuretics Carbonic Anhydrase Inhibitors (CAIs)
acetazolamide (Diamox)
methazolamide
dichlorphenamide

7. Diuretics Carbonic Anhydrase Inhibitors Indications
Adjunct drugs 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:
Edema*
Epilepsy
High-altitude sickness
Acetazolamide (Diamox) 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 2-4 days

8. Diuretics Carbonic Anhydrase Inhibitors: Adverse Effects
Metabolic acidosis
Anorexia
Hematuria
Photosensitivity
Melena
Hypokalemia
Drowsiness
Paresthesias
Urticaria

9. Diuretics Loop Diuretics Mechanism of Action
Act directly on the ascending limb of the loop of Henle to inhibit chloride and sodium resorption
Increase renal prostaglandins, resulting in the dilation of blood vessels and reduced peripheral vascular resistance
bumetanide (Bumex)
ethacrynic acid (Edecrin)
furosemide (Lasix)

10. Diuretics 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-diastolic pressure
Potassium and sodium depletion

11. Diuretics Loop Diuretics -- Indications
Edema associated with HF or hepatic or renal disease
Control of hypertension
Increase renal excretion of calcium in patients with hypercalcemia
Certain cases of HF resulting from diastolic dysfunction

12. Diuretics Loop Diuretics -- Adverse Effects
Body System Adverse Effects
CNS Dizziness, headache, tinnitus, blurred vision
GI Nausea, vomiting, diarrhea
Hematologic Agranulocytosis, neutropenia, thrombocytopenia
Metabolic Hypokalemia, hyperglycemia, hyperuric

13. Diuretics Osmotic Diuretics Mechanism of Action
Work mostly in the proximal tubule
Nonabsorbable, producing an osmotic effect
Pull water into renal tubules from the surrounding tissues
Inhibits tubular resorption of water and solutes
Increases glomerular filtration and renal plasma
Reduces excessive intraocular pressure

14. Diuretics 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
NOT indicated for peripheral edema

15. Diuretics Osmotic Diuretics -- Adverse Effects
Convulsions
Thrombophlebitis
Pulmonary congestion
Also headaches, chest pains, tachycardia, blurred vision, chills, and fever

16. Diuretics Osmotic Diuretics
mannitol (Osmitrol)
Intravenous infusion only
May crystallize when exposed to low temperatures—use of a filter is required

17. Diuretics Potassium-Sparing Diuretics Mechanism of Action
Interfere with sodium-potassium exchange in collecting ducts and convoluted tubules
Competitively bind to aldosterone receptors
Block the resorption of sodium and water
Prevent potassium from being pumped into the tubule, thus preventing its secretion
Competitively block the aldosterone receptors and inhibit its action
Sodium and water are excreted

18. Diuretics Potassium-Sparing Diuretics
amiloride (Midamor)
spironolactone (Aldactone)
triamterene (Dyrenium)
Also known as aldosterone-inhibiting diuretics

19. Diuretics Potassium-Sparing Diuretics Indications
spironolactone and triamterene
Hyperaldosteronism
Hypertension
Reversing the potassium loss caused by potassium-losing drugs
Certain cases of heart failure
Liver failure
Amiloride
Treatment of HF

20. Diuretics Potassium-Sparing Diuretics Adverse Effects
Body System Adverse Effects
CNS Dizziness, headache
GI Cramps, nausea, vomiting, diarrhea
Other Urinary frequency, weakness
**hyperkalemia**

21. Diuretics Potassium-Sparing Diuretics Adverse Effects
Spironolactone
Gynecomastia
Amenorrhea
Irregular menses
Postmenopausal bleeding

22. Diuretics Thiazide and Thiazide-like Diuretics Mechanism of Action
Actions:
Acts in the distal convoluted tubule
Inhibit tubular resorption of sodium, chloride, and potassium ions
Result: water, sodium, and chloride are excreted
Potassium is also excreted to a lesser extent
Dilate the arterioles by direct relaxation
Results:
Lowered peripheral vascular resistance
Sodium, water, chloride and potassium are excreted

23. Diuretics Thiazide and Thiazide-like Diuretics
Thiazide diuretics
hydrochlorothiazide (Esidrix, HydroDIURIL)
chlorothiazide (Diuril)
trichlormethiazide (Metahydrin)
Thiazide-like diuretics
chlorthalidone (Hygroton)
metolazone (Mykrox, Zaroxolyn)

24. Diuretics Thiazide and Thiazide-like Diuretics Precautions
Thiazides should not be used if creatinine clearance is less than 30 to 50 mL/min (normal is 125 mL/min)
Metolazone (Zaroloxyn) remains effective to a creatinine clearance of 10 mL/min

25. Diuretics Thiazide and Thiazide-like Diuretics Indications
Hypertension – first line drug for HTN
Edematous states
Idiopathic hypercalciuria
Diabetes insipidus
Heart failure due to diastolic dysfunction
Adjunct drugs in treatment of edema related to HF,
hepatic cirrhosis, corticosteroid therapy

26. Diuretics Thiazide and Thiazide-like Diuretics Adverse Effects
Body System Adverse Effects
CNS Dizziness, headache, blurred vision, paresthesias, decreased libido
GI Anorexia, nausea, vomiting, diarrhea
GU Impotence
Integumentary Urticaria, photosensitivity
Metabolic Hypokalemia, glycosuria, hyperglycemia,
hyperuricemia
OTHER EFFECTS ALSO

27. Diuretics Nursing Implications
Thorough patient history and physical examination
Assess baseline fluid volume status, intake and output, serum electrolyte values, weight, and vital signs— especially postural BPs/orthostatic BPs
Assess for disorders that may contraindicate or necessitate cautious use of these drugs
Monitor serum K+ levels during therapy
K+ supplements are usually recommended to maintain K+ levels at approximately 4 mEq/L

28. Diuretics Patient Education
Instruct patients to take in the morning as much as possible to avoid interference with sleep patterns
Teach patients to maintain proper nutritional and fluid volume status
Teach patients to eat more potassium-rich foods when taking any but the potassium-sparing drugs
Foods high in potassium include bananas, oranges, dates, raisins, plums, fresh vegetables, potatoes, meat, and fish, apricots, whole grain cereals, legumes

29. Diuretics Patient Education
Patients taking diuretics along with a digitalis preparation digoxin (Lanoxin) 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
Change positions slowly, and to rise slowly after sitting or lying to prevent dizziness and possible fainting related to orthostatic hypotension

30. Diuretics Patient Education
Encourage patients to keep a log of their daily weight
A weight gain of 2 or more pounds a day or 5 or more pounds a week should be reported immediately
Encourage patients to return for follow-up visits and labwork
Notify physician if you are ill with nausea, vomiting, and/or diarrhea because fluid loss may be dangerous

31. Diuretics Patient Education
Excessive consumption of licorice can lead to an additive hypokalemia in patients taking thiazides
Signs and symptoms of hypokalemia include muscle weakness, constipation, irregular pulse rate, and overall feeling of lethargy
Notify the physician immediately if rapid heart rate or syncope occurs (reflects hypotension or fluid loss)

32. Review Diuretics are used for which of the following
reasons? (Select all that apply.)
1. treat hypertension
2. treat edema with heart failure
3. increase urine fl ow
4. treat hyperuricemia (increased uric
acid level)

33. Review Potassium-sparing diuretics are administered
in combination with other types
of diuretics to do which of the following?
(Select all that apply.)
1. treat hypertension
2. treat heart failure
3. prevent hypokalemia
4. prevent hyperkalemia

34. Review The most potent class of diuretics currently available is:
1. thiazide-type.
2. potassium-sparing type.
3. loop-type.
4. carbonic anhydrase inhibitor.

35. Review Patients with diabetes mellitus receiving a
diuretic should be observed for:
1. hypoglycemia.
2. hyperglycemia.
3. hyperkalemia.
4. normonatremia.