Diuretics Flashcards
Diuresis
Increased water loss
Diuretic general
Diuretic Drugs: increase urine output and remove excess fluid
First line drugs for heart failure and hypertension. Also good for a
Most use excretion of sodium and water
BP CONTROL
BP = Cardiac output x total peripheral resistance
Cardiac output = HR x Stroke volume (blood volume)
Nephron review
- Glomerulus
- Proximal convoluted tubule
- Loop of henle
- Distal convoluted tubule
- Collecting duct
Loop of henle and collecting duct are in the medulla
Sodium controlling water movement
67% in Proximal convuluted tubule
20-25% of Na is reabsorbed in loop of Henle
7% in the distal tubules
1-2% in collecting ducts
Diuretic drug actions
Blocks Na reabsorption and causes fluid loss
- Hypovolemia
- Acid-base imbalances
- Alter electrolyte levels
Types of Diuretics
- Loop diuretics
- Thiazide and thiazide-liek diuretics
- Potassium-sparing diuretics
- Osmotic diuretics - not focusing on
Loop Diuretics general
Furosemide (Lasix)
“High ceiling” diuretics
Act in the ascending limb of the loop of henle
- Inhibits sodium and chloride transporter
Loop Diuretics - Med Effects
Significant diuresis
- significant loss of fluid
- reduced edema
- reduced venous return
- reduced CO
Potassium depletion
Loop Diuretics: Indications
Edema associated with heart failure or hepatic or renal disease
Control of hypertension
Increase renal excretion of calcium for patients with hypercalcemia
Loop Diuretics: Contraindication
- Known drug allergy
- Allergy to sulfonamide antibiotics (related structure)
- Hepatic coma
- Severe electrolyte loss
Furosemide (Lasix)
Secreted into nephron fluid
- luminal site of action
- Crosses placenta and enters breast milk
- High albumin binding (91-97%)
- Metabolized in liver
Loop diuretics - Adverse efffects
Hypokalemia (normal is 3.5-5)
- Irregular heartbeat, potentially fatal dysrhythmias
- Muscle weakness/lethargy
- Leg cramps
- GI disturbances (constipation)
Hyperglycemia
Furosemide Interactions
Patients using digoxin (symptom relief from heart failure) needs to have normal potassium levels
- Furosemide can increase digoxin toxicity
- Increased hypokalemia with other diuretics
- Increased levels of lithium (bi polar disorder)
- May cause hyperglycemia
Thiazide and Thiazide-like Diuretics
Hydrochlorothiazide (Hydrodiuril)
Very frequently used for hypertension
Thiazide Actions
Inhibits reabsorption of sodium and chloride in the distal convoluted tubule
Depletion of sodium and water - reduced blood volume
Lowered peripheral vascular resistance
Hydroholorthiazide
Oral administration - quick absorption
Excreted mostly unchanged by kidneys. Site of action in luminal membrane
Thiazide Med Effects
Drug effect reduced as kidney function decreases
Not to be used if creatinine is below 30ml/min
- normal is 125ml/min (GFR)
Thiazide Indications
Hypertension
- First line treatment
- Single or combination (loop)
Edematous states
- treatment of HF, hepatic cirrhosis
Thiazide Contraindications
Severe kidney failure
- Known drug allergy
- Hepatic coma
- Anuria - absence of urine formation
Thiazide Adverse Effects
Hypokalemia*
Hyperuricemia
Hyperglycemia (inhibits insulin secretion)
Genitourinary system
- Impotence
Thiazide Interactions
Digoxin
- increased risk of toxicity due to hypokalemia
Antidiabetic drugs
- reduces effect from diabetic drugs so may lead to hyperglycemia
Potassium-sparing Diuretics
Spironolactone (aldactone)
- Aldosterone receptor blocker
- Onsent is 24-48 hours
- peka 2-3 days
- Other P-S drugs are Na channel blockers
Collecting tubules of nephrons
- Limited effectiveness used on their own
Used to prevent hypokalemia
P-S Actions
Reduced sodium-potassium exchange, body retains K+
Blocks the reabsorption of sodium and water usually induced by aldosterone
