Chapter 41: Diuretics Flashcards
What three things does the renal system help regulate?
ECF volume and compensation, acid-base balance, excretion of metabolic wastes and foreign substances.
What does the renal system play a significant role in doing?
drug elimination
What are the essential physiological functions of the renal system?
Stimulates erythropoiesis and activates vitamin D
What is the active form of of vitamin D?
Calcitriol
Kidneys are the site of what?
Parathyroid hormone functioning
What 2 ions are the most prevalent of the filtrate?
Sodium and chloride
What is the first step in urine formation?
Filtration
What is the best measure of overall function of the kidney
GFR
What types of particles are easily filtered through the kidneys?
Small, water soluble, lipid phobic, and ionized
What type of process is filtration?
Non-selective
What percent of filtered sodium and chloride is reabsorbed at the proximal convoluted tubule?
65%
What type of transport does solutes use?
Active transport
What has almost 100% reabsorption in the proximal convoluted tubules?
Filtered bicarbonate and potassium
What type of solute does water use?
Passive transport (osmotic pressure)
What is absorbed equally in the proximal convoluted tubules?
solutes and water
What percent of filtered sodium and chloride is reabsorbed at the early distal convoluted tubule?
10%
What percentage of sodium and chloride is reabsorbed in the loop of henle?
20
What type of diuretics work at the early distal convoluted tubules?
Thiazide diuretics
What type of diuretics is more potent?
Loop diuretics
What two processes happen at the distal nephron?
sodium and potassium exchange
What is aldosterone’s main goal
to reabsorb sodium
What determines the final concentration of urine
ADH
What test can you use to find urine weight?
Specific gravity
What is the normal specific gravity
0.010-0.030
Aldosterone causes stimulation of the distal nephron cells to do what?
Synthesize more protein pumps responsible for sodium and potassium transport
Amount of diuresis is directly related to what?
The amount of sodium and chloride that is not reabsorbed (because diuretics are blocking the reabsorption)
The form of the drug depends on what?
The pH of urine
Diuretics are widely used in the management of what 2 conditions
Edematous and non edematous
Diuretics are drugs that promote the renal excretion of what three things?
sodium, chloride, and water
What are examples of edematous conditions?
heart failure, liver failure, and renal failure
What is an example of a nonedamatous condition?
HTN (by depleting sodium)
What are two common adverse effects of diuretics?
Hypovolemia and electrolyte and acid-base imbalances
Diuretics are sometimes used to prevent renal failure by what>
d/t their ability to maintain urine flow
What are the two subcategories of potassium sparing diuretics?
aldosterone antagonists and non aldosterone antagonists
What diuretics are used primarily to reduce IOP & NOT increase urine production
Carbonic Anhydrase inhibitor
What is the prototype for loop diuretics?
Furosemide
How does furosemide work?
Inhibits sodium & chloride reabsorption in the ascending limb of the loop of henle.
(prevents passive reabsorption of water)
Due to furosemide’s ability to cause significant diuresis, what can this drug lead to?
Severe dehydration
What type of diuretic is effective in patient’s with renal impairment
Furosemide (lasix) / loop diuretic
What diuretic has a high ceiling effect?
Furosemide
When would furosemide be given IV route?
In situations needing rapid and massive mobilization of fluids.
How is effectiveness monitored while on diuretics?
- daily weight
-comparing urine output (output should exceed intake)
-decreased edema
-clear lung sounds
what serum levels are decreased in patients who are taking loop diuretics
sodium, potassium, chloride, calcium, magnesium, HDL
If a patient is taking loop diuretics begins to complain about joint pain while on furosemide, what would we be concerned about?
the patient could be developing gout
what are some drug-drug interactions with loop diuretics?
antihypertensives, digoxin, amino-glycosides, lithium, NSAIDs, and potassium sparing diuretics
what effects can NSAIDs have on furosemide?
can blunt the effects of furesomide
What are some potential adverse effects seen with furosemide?
-hypovolemia
-hypokalemia
-hyponatremia
-hypochloremia
-dehydration
-ototoxicity
-hypotension
-dysthymias (potassium)
-acid-base imbalance (metabolic alkalosis0 loss of hydrogen ions)
using gentamicin along with fursomide can increase the risk of what
ototoxicity
What drug has a positive interaction with furosemide?
Potassium-sparing diuretics
What diuretic is used as first-line treatment for HTN?
hydrochlorothiazide
promotion of diuresis while taking a thiazide diuretic is dependent on what
adequate renal function
hydrochlorothiazide has the same adverse effects as furseomide except for what two things
ototoxicity and hypocalcemia
What diuretic would you be concerned with a sulfa allergy?
hydrochlorothiazide
what effect does hydrochlorothiazide have on bones?
helps preserve bone integrity
What diuretic protects against post-menopausal osteoporosis?
hydrochlorothiazide
thiazide diuretics have the same drug-drug interactions as loop except for what drug
amino-glycosides (gentamicin)
what can thiazide diuretics help prevent against?
calcium induced renal calculi
Due to the enhanced action of ADH that thiazide diuretics have, what can these drugs be used for?
diabetes insipidus
What is an indirect-acting potassium-sparing diuretic?
Spironolactone
what type of adverse effects does spironolactone have?
endocrine and androgenic effects like gynecomastia, impotence, hirsituitism
What must be present for spironolactone to be effective?
Aldosterone
what are the four properties of mannitol
freely filtered at the glomerulus, undergoes minimal tubular reabsorption and metabolism and it is pharmacologically inert
How long does it take to develop therapeutic effects?
up to 48 hours (delayed)
what type of diuretic has no actions on it’s own
osmotic diuretics (mannitol)
what two things are mannitol helpful for?
oliguria and anuria
Spironolactone acts at the late distal tubule to decrease what two things?
- sodium reabsorption
- potassium secretion
the degree of diuresis while taking mannitol is directly related to what
the concentration of mannitol in the filtrate
mannitol has no effect on what?
electrolyte excretion
mannitol can be used for what other clinical things?
prevention of renal failure, reduction of ICP due to cerebral edema and reduction of IOP before opthalamic surgeries
what is a major ADR for mannitol?
edema
due to the possibility of edema while taking an osmotic diuretic, what patients should we be cautious about giving this drug to?
patients who are experiencing heart failure and peripheral edema
Can spironolactone be combined with other diuretics?
Yes, it is a weak diuretic so it is usually combined.
Which diuretic has cardioprotective effects?
Spironolactone
What is an example of a direct-acting potassium sparing diuretic?
Triamterene
Which potassium-sparing diuretic works more rapidly? Spironolactone or triamterene?
triamterene
What is the major adr for potassium-sparing diuretics?
Hyperkalemia
What may be needed for hyperkalemia r/t the use of potassium-sparing diuretics?
Insulin or Kayexalate
What are 4 drug-drug interactions with potassium-sparing diuretics?
-potassium supplements
-ACE-inhibitors
-Angiotensin receptor blockers (ARBS)
-Direct renin inhibitors (DRI)
What should patients avoid in potassium-sparing diuretics?
foods high in potassium (bananas, potatoes, strawberries, salt substitutes)
