Drugs That Affect Diuresis

Question 1

What is Diuresis?

Answer 1

The process of ridding the body of fluids through the increased production of urine and the excretion of water and electrolytes

Question 2

What do diuretics do?

Answer 2

• Drugs that are diuretics are used to decrease fluid volume in pathologic conditions in which the body cannot self-regulate fluid volume effectively
• Diuretics decrease renal reabsorption of sodium and promote its excretion in water

Question 3

What does hypervolemia result from?

Answer 3

Excessive sodium and water retention

Question 4

What does peripheral edema do to cardiac workload and tissue perfusion?

Answer 4

Increases cardiac workload

Decreases tissue perfusion

Question 5

What pathological conditions do diuretics help to treat?

Answer 5

CHF
Pulmonary Edema
Hypertension
Kidney Disorders

Question 6

Parts of the nephron

Answer 6

Glomerulus
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule

Question 7

Three functions of the nephron

Answer 7

Filtration of the blood
Reabsorption
Active tubular secretion

Question 8

What diuretic works in the proximal convoluted tubule?

Answer 8

Mannitol (65% NaCl reabsorption)

Question 9

What diuretic works in the Loop of Henle?

Answer 9

Furosemide (Lasix) (20% NaCl reabsorption)

Question 10

What diuretic works in the early distal convoluted tubule?

Answer 10

Hydrochlorothiazide (HCTZ) (10% NaCl reabsorption)

Question 11

What diuretic works in the late distal convoluted tubule?

Answer 11

Spirolactone and Triamterene (1-5% Na and K –> spares potassium!)

Question 12

Thiazide Diuretics

Answer 12

The thiazides comprise the largest group of diuretics

They are related structurally to the antibacterial sulfonamides (Sulfa drugs that treat infections)

Question 13

Examples of Thiazide Diuretics

Answer 13

Thiazide diuretics include hydrochlorothiazide (HydroDIURIL), benzthiazide (Exna), chlorothiazide (Diuril), chlorthalidone (Hygrotin), and metolazone (Zaroxolyn)

Question 14

Hydrochlorothiazide (HCTZ)

Answer 14

• Manages HTN alone or with other drugs
• Also used in treating edema resulting from CHF, hepatic cirrhosis, renal disease, and long-term steroid or estrogen therapy
• Acts in the distal tubule and possibly in the diluting segment of the ascending loop of Henle
• Increases the excretion of sodium and chloride in the distal convoluted tubule by slightly inhibiting the ion pumps that work in sodium and chloride reabsorption
• A weak diuretic effect (of the three potent, potassium-wasting diuretics), because most of the sodium is reabsorbed before the distal tubule
• Prototype thiazide diuretic

Question 15

When taking HCTZ, the patient is at risk for…

Answer 15

Hypokalemia, acid/base imbalance, hypomagnesemia, and hypercalcemia

Question 16

HCTZ _______ excretion of potassium, bicarbonate, and magnesium; and _______ excretion of calcium.

Answer 16

Increases; decreases

Question 17

HCTZ may ________ glomerular filtration and ______ BUN.

Answer 17

Decrease; increase

Question 18

Contraindications of HCTZ

Answer 18

severe renal impairment, hepatic coma (will not be able to metabolize the drug), and hypersensitivity to the drug or to sulfonamide antibiotics

Question 19

Adverse Effects

Answer 19

Mostly due to effects of fluid loss or imbalance

Many drug interactions

Question 20

Before giving HCTZ, determine:

Answer 20

allergy to sulfa (safety!), renal status (severe impairment of the kidney – this drug will be of no benefit), hepatic status, blood glucose levels (can increase; contraindication for diabetics), lipid, and uric acid levels (can increase; contradiction for patients with gout)

Question 21

Loop Diuretics

Answer 21

• Work in the Loop of Henle to inhibit the reabsorption of sodium and chloride
• Exert a powerful effect of fluid and electrolyte balance
• Called high-ceiling diuretics

Question 22

Examples of Loop Diuretics

Answer 22

furosemide (Lasix), bumetanide (Bumex), ethacrynic acid (Edecrin), and torsemide (Demadex)

Question 23

Furosemide (Lasix)

Answer 23

• A potent diuretic that is effective in reducing peripheral edema from CHF and hepatic and renal diseases, including nephrotic disease
• It is highly effective in the treatment of pulmonary edema → Drug of choice, IV route
• It also is effective in the treatment of HTN and is the first choice over thiazides in patients with pre-existing renal disease, because, unlike thiazides, it does not decrease glomerular filtration rate
• Furosemide inhibits the reabsorption of sodium, chloride, and water in the ascending loop of Henle
• It also has some effect in the proximal and distal tubules

Question 24

Furosemide ________ excretion of sodium, potassium, chloride, magnesium, calcium, and water

Answer 24

Increases

Question 25

What is the difference between HCTZ and Lasix?

Answer 25

Patient is at risk for hypocalcemia because calcium is excreted

Question 26

What lab values can be increased when taking Furosemide?

Answer 26

blood glucose, low-density lipoprotein, total cholesterol, uric acid and triglyceride levels

Question 27

Effects with IV administration of Furosemide occur within ___ minutes

Answer 27

10 --> cardiac arrest has been reported to occur

Question 28

What kind of toxicity may occur with rapid IV push administration of Furosemide?

Answer 28

Ototoxicity

Question 29

What is the recommended method for IV push administration of Furosemide?

Answer 29

20-40 mg of IV should be given over at least 1 to 2 minutes to decrease risk of ototoxicity (SLOW IV PUSH)

Question 30

Potassium Sparing Diuretics

Answer 30

- Promote sodium and water excretion in the distal tubule; at the same time, potassium is not excreted; rather, it is reabsorbed - Produce weak diuresis and antihypertensive effects when used alone – is usually used with another diuretic - More frequently used in combination with loop and thiazide diuretics to minimize potassium loss because they work synergistically with other diuretics

Question 31

When taking a potassium sparing diuretic, the patient is at risk for...

Answer 31

Hyperkalemia

Question 32

Examples of Potassium Sparing Diuretics

Answer 32

triamterene (Dyrenium), amiloride (Midamor), and spironolactone (Aldactone)

Question 33

Triamterene (Dyrenium)

Answer 33

- Nonaldosterone Antagonist - Used to manage edema and hypertension; typically used with other diuretics because it allows potassium to be reabsorbed and sodium to be excreted - Inhibits transport of sodium in the distal tubules independent of aldosterone; this causes increased loss of sodium, chloride, water, bicarbonate, and calcium; the drug promotes the retention of potassium and magnesium (patient could develop hyperkalemia and hypermagnesium) - Increases serum uric acid levels - Adverse effects related to electrolyte imbalance, particularly hyperkalemia, which may be fatal - Limit the patient’s intake of potassium

Question 34

Spironolactone (Aldactone)

Answer 34

- Aldosterone Antagonist - Works in the distal tubule to increase sodium and water loss and to retain potassium - Interferes with testosterone synthesis, which leads to altered estrogenic and androgenic activity; a major use is in diagnosing and treating primary hyperaldosteronism (endocrine disorder) - Adverse effects: impotence, menstrual irregularities, and gynecomastia - Interacts with the salicylates (cannot take this drug with aspirin)

Question 35

Osmotic Diuretics

Answer 35

- Increase osmotic pressure and pull fluid into the vascular space from the interstitum; are not reabsorbed by the tubules and so prevent water reabsorption; also prevent the reabsorption of sodium and chloride

Question 36

Examples of Osmotic Diuretics

Answer 36

mannitol (Osmitrol), glycerin, isosorbide, and urea

Question 37

Mannitol (Osmitrol)

Answer 37

- Major uses include: - Preventing and treating ARF - Reducing intracranial pressure in cerebral edema - Reducing intraocular pressure when other drugs have not worked - Promoting excretion of toxic substances in urine - Prototype

Question 38

Glycerin (Glycerol)

Answer 38

- An osmotic agent given orally to reduce intraocular pressure before ophthalmic surgery and during acute glaucoma attacks

Question 39

Isosorbide (Ismotic)

Answer 39

- Used to provide short-term reduction of intraocular pressure before and after intraocular surgery, and to interrupt acute attacks of glaucoma

Question 40

Urea (Ureaphil)

Answer 40

- Administered by IV infusion | - Used to decrease intracranial pressure and to reduce intraocular pressure

Question 41

Carbonic Anhydrase Inhibitors

Answer 41

- Used to treat chronic open-angle glaucoma; also used in acute closed-angle glaucoma when delay of surgery is desired to reduce intraocular pressure; as an adjunct in treating edema resulting from CHF or use of drugs; as an adjunct in treating epilepsy; and in preventing and treating acute motion sickness

Question 42

Examples of Carbonic Anhydrase Inhibitors

Answer 42

acetazolamide (Diamox), methazolamide (Neptazane), and dichlorphenamide (Daranide)