Diuretic Drugs - Ch. 44 Flashcards
Diuresis
Increased water loss
What do diuretic drugs do?
Increase urine output
Remove excess fluid
Accelerate the rate of urine formation
What are first-line diuretics used for?
Heart failure
Hypertension
-acute edematous states
How do most diuretic drugs work?
By excretion of sodium and water
How do diuretics affect blood pressure?
They control sodium and chloride which controls how much water is excreted, and the volume of ECF which controls BP
Sodium controls the movement of what?
Water
-Where sodium goes, water follows
20% to 25% of all sodium is reabsorbed in which part of the nephron?
Loop of Henle
7% of all sodium is reabsorbed in which part of the nephron?
Distal tubules
1-2% of all sodium is reabsorbed in which part of the nephron?
Collecting ducts
What happens if water is not reabsorbed?
It is excreted as urine
What happens when Na reabsorption is blocked?
Excessive fluid loss (dehydration)
Acid-base imbalances
Altered electrolyte levels
What are the types of diuretics?
Loop diuretics
Thiazide and thiazide-like diuretics
Potassium-sparing diuretics
Osmotic diuretics
Which types of diruetics block NaCl reabsorption?
Loop diuretics
Thiazide and thiazide-like diuretics
Potassium-sparing diuretics
What are examples of Loop diuretics?
!! Furosemide (Lasix)
Bumetanide (Burinex)
Ethacrynic acid (Edecrin)
Loop diuretics are also known as?
‘high ceiling’ diuretics
Which part of the nephron do Loop diuretics act in?
Ascending Loop of Henle
What is the mechanism of action of Loop Diuretics?
Inhibits sodium and chloride transporter on luminal membrane so it gets secreted into nephron fluid
Furosemide
Significant diuresis
-Causes significant fluid loss
What does decreased fluid volume cause?
Reduced edema
Reduced venous return (reduced CO)
What is Furosemide used for?
Edema associated with heart failure or hepatic or renal disease
Control of hypertension
Increase renal excretion of calcium in clients with hypercalcemia
What adverse effects are associated with Furosemide?
Excessive fluid loss
-Low Na, Cl
-Water loss —> Dehydration
—> Hypotension
—> thrombosis/embolism
Potassium depletion!! Hypokalemia
Hyperuricemia (may lead to gout)
Hyperglycemia
What levels of potassium are considered hypokalemic?
Below the normal range of 3.5-5mmol/L
How is Hypokalemia treated?
-Treated with K supplements or K-sparing diuretic
Hypokalemia symptoms?
irregular heartbeat
-Potentially fatal dysrhythmias
Muscle weakness/lethargy
Leg cramps
GI disturbances (constipation)
How does Furosemide interact with Digoxin?
Patients need to be monitored for hypokalemia
Increased digoxin toxicity
Increases hypokalemia with other diuretics, glucosteroids
How does furosemide interact with aminoglycosides?
Ototoxicity
How does Furosemide interact with lithium?
May increase the effects of lithium
-Used for bipolar
How does furosemide interact with antidiabetic drugs?
May decrease hypoglycemic effect and cause hyperglycemia
Where in the nephron do Thiazide/Thiazide-like diuretics take place?
Distal convoluted tubule
What is the mechanism of action of Thiazide diuretics?
Inhibit reabsorption of sodium and chloride ions which results in excretion of water, sodium and chloride
(reduced blood volume)
What do Thiazides have that is different from loop diuretics?
Different protein targets
Which diuretics are more powerful, loop or thiazide?
Loop diuretics are MORE powerful
Thiazide diuretics are also know as?
‘Low ceiling’ diuretics
Examples of thiazide/thiazide-like diuretics?
Hydrochlorothiazide
Chlorthalidone
metolazone
How is Hydrochlorothiazide administered?
PO
What are thiazide diuretics used for?
Hypertension
-First-line treatment
-single or combo therapy
Edematous states
-Adjunct agents in the treatment of HF, hepatic cirrhosis
What adverse effects are associated with Thiazide Diuretics?
Hypokalemia
Hyperuricemia
Hyperglycemia (inhibits insulin secretion)
Impotence (erectile dysfunction)
How do Thiazide diuretics interact with Digoxin?
Increased risk or toxicity due to hypokalemia (same as loop)
How do Thiazide diuretics interact with anti-diabetic drugs?
Reduces hypoglycemic effect, so may lead to hyperglycemia
Where in the nephron do Potassium-sparing diuretics take place?
Collecting tubules
Why do Pottasium-sparing diuretics have limited effectiveness when used on their own?
Collecting tubule site of action only accounts for 1-2% of Na reabsorption
Examples of Potassium-sparing diuretics?
Spironolactone (Aldactone)
Amiloride (midamor)
Triamterene (available only in combination with
hydrochlorothiazide - Riva-Zide)
What does Spironolactone (aldactone) block?
Aldosterone receptors
What do Amiloride (midamor) and Triamterene block?
Na channels
When is the onset of Spironolactone?
Onset: 24-48 hours
When is the peak of Spironolactone?
2-3 days
What is the mechanism of action of Spironolactone?
Antagonist at aldosterone receptors
-Blocks the reabsorption of sodium and water usually induced by aldosterone
Reduces sodium-potassium exchange
-Body retains potassium
What is Spironolactone used for?
Edema associated with heart failure
Hypertension
Reversing the potassium loss caused by potassium-losing drugs (combination therapy)
Hyperaldosteronism
What adverse effects are associated with spironolactone?
Hyperkalemia
-Above 3.5-5mmol/L
Sex-hormone like effects
Hyperkalemia symptoms?
Cardiac dysrhythmias (tachycardia)
Muscle weakness
Gi disturbances (Cramps, nausea, vomiting, diarrhea)
What sex hormone like effects do Spironolactone cause?
Amenorrhea (absence of menstruation)
Irregular menses
Postmenopausal bleeding
Gynecomastia (increase breast tissue in males)
What drugs do potassium-sparing drugs have interactions with?
Other heart failure drugs that increase plasma K+
RAAS drugs e.g, ACE inhibitors
Potassium supplements
When should a patient take diuretics?
In the morning to avoid interference with sleep patterns
What should a nurse monitor in a patient on diuretics?
Serum potassium levels during therapy
What should a nurse teach a patient who is on diuretics?
Eat more potassium-rich foods when taking loop or thiazide diuretics
What are some foods high in potassium?
Bananas
Oranges
Raisins
Plums
Fresh vegetables
Legumes
Potatoes
What should a nurse monitor in a patient who is taking diuretics and digoxin?
Digoxin toxcitity
Symptoms of digoxin toxcity?
Fatigue
GI problems
Changes in heart rate/rhythm
Loss of appetite (anorexia)
Visual disturbances
What should diabetic patients who are taking thiazide and/or loop diuretics monitor?
Monitor blood glucose and watch for elevated glucose levels
Patients should notify a physician if they experience what while taking diuretics?
Rapid heart rate or syncope (reflects hypotension and fluid loss)
Rapid weight loss
What should the nurse teach the patient to do to prevent dizziness and possible fainting related to orthostatic hypotension?
Change positions slowly and to rise slowing after sitting or lying down
What kind of therapeutic effects should a nurse monitor for?
Reduction in edema, fluid volume overload, Heart failure
Reduction of hypertension; ICP
What is a kind of osmotic diuretic?
IV mannitol
What is the mechanism of action of IV mannitol?
Produces an osmotic force in nephron fluid
(Not reabsorbed)
Inhibits tubular reabsorption of H2O, producing a RAPID diuresis
Where in the nephron does IV mannitol take place?
Proximal tubule
How does IV mannitol affect electrolytes?
Causes only slight loss of electrolytes
What are osmotic diuretics used for?
Early ARF (acute renal failure)
-keeps fluid moving
Non-renal treatments
What non-renal treatments are osmotic diuretics used for?
Reduction of intracranial pressure (ICP)
Cerebral edema (Fluid from brain entering blood)
Reduces excessive intraocular pressure
Osmotic diuretics are contraindicated for patients who?
Have a known drug allergy
Severe kidney disease
Pulmonary edema (loop diuretics instead, greater fluid reduction)
Active intracranial bleeding
What adverse effects are associated with osmotic diuretics?
Convulsions
Thrombophelbitis
Pulmonary congestion
Headaches, nausea, vomiting, chest pain, tachycardia, blurred vision, chills and fever
