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70 Cards in this Set
- Front
- Back
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What is a diuretic?
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drug that increases the excretion rate of urine
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Where does mannitol act?
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proximal tubule
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Where does Acetazolamide act?
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proximal tubule
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Where do loop diuretics act?
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medullary and cortical ascending limb of the loop fo Henle
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Where do thiazide-like diuretics act?
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distal tubule +/- proximal tubule inner medullary collecting tubule
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Where does spironolactone act?
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collecting tubulecollecting tubule
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Where does amiloride act?
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collecting tubule
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Where does Triamterene act?
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collecting tubule
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What is the mechanisms of diuresis with mannitol?
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loss of H2O in excess of Na and Cl
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What is the mechanism of diuresis with acetazolamide?
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loss of Na, HCO3, Cl, K
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What is the mechanism of diuresis with loop diuretics?
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loss of Na, Cl, K, Mg, Ca
inhibits concentration and filtration |
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What is the mechanism of diuresis with thiazide-like diuretics?
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loss of Na, Cl, K, inhibits dilution, not concentration, increases blood Ca and uric acid
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What is the mechanism of spironolactone diuresis?
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loss of Na and Cl
K sparing |
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What is the mechanism of amiloride diuresis?
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loss of Na and Cl, K sparing
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What is the mechanism of triamterene diuresis?
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loss of Na and Cl, K sparing
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What kind of diuretic is mannitol?
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osmotic
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What drug is an osmotic diuretic?
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mannitol
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What is mannitol's main MOA?
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IV volume expansion
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How does mannitol work?
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filtered at glomerulus, not reabsorbed, increases the osmolality of filtrate, limits diffusion fo H2O across the epithelium
Na concentration increases until Na transport is attenuated |
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What is the net result of mannitol?
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H2O loss with some increase in NaCl excretion
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Why do you use mannitol?
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reduction in intracranial pressure for neurosurgical procedures
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What is the toxicity of mannitol?
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pulls H2O out of cells, leads to expansion of EC volume, pulmonary edema in patients with CHF, headache, nausea, vomiting
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What kind of drug is acetazolamide?
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carbonic anhydrase inhibitor, sulfonamide
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What is acetazolamide's MOA?
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noncompetitive inhibition of carbonic anhydrase in proximal tubule prevents reabsorption of NaHCO3, increases secretion of NaHCO3, excreted with H2O
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How is acetazolamide excreted?
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by kidney, organic acid transport system in proximal tubule
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What is the toxicity of acetazolamide?
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metabolica cidosis, renal stones, K and HCO3 wasting, decreased NH3 excretion
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To whom should you not give acetazolamide?
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hepatic cirrhosis, sulfa allergy
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What does an idiosyncratic sulfa allergy present with?
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fever, rash, bm suppression, interstitial nephritis
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What kind of drug is furosemide?
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loop diuretic, sulfonamide, carboxylic acid
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What kind of drug is ethacrynic acid?
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loop diuretic, carboxylic acid
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What is furosemide's main MOA?
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inhibits cotransport of Na, Cl, K at luminal membrane of thick ascending limb of loop of Henle
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What is ethacrynic acid's main MOA?
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inhibits cotransport of Na, Cl, K at luminal membrane of thick ascending limb of loop of Henle
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How does furosemide work?
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inhibition of reabsorption of NaCl in thick acsending limb, loss of NaCl in the urine, abolishes hypertonicity of renal medullary interstitium, reduces H2O reabsorption in collecting tubule and ducts leading to marked diuresis
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How does ethacrynic acid work?
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inhibition of reabsorption of NaCl in thick acsending limb, loss of NaCl in the urine, abolishes hypertonicity of renal medullary interstitium, reduces H2O reabsorption in collecting tubule and ducts leading to marked diuresis
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What part of the kidney reabsorbs most of the filtered Na?
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proximal tubule
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What transporter defect causes Bartter's syndrome?
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Na/K/Cl in luminal membrane of TAL of loop of Henle
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Where do the most efficacious diuretics act?
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ascending limb, causes most substantial urinary loss of Ca and Mg
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How are loop diuretics gotten rid of?
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secretion in proximal tubule
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How do you dose loop diuretics?
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threshold effect, titrate to point at which you get diuresis, give more frequently rather than higher doses to get better effect
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What are the edematous uses of loop diuretics?
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pulmonary edema, mod- severe CHF, nephrotic syndrome, accelerated/malignant hypertension, ascites, edema due to renal insufficiency
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What are the non-edematous uses of loop diuretics?
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HTN in patients with low GFR, hypercalcemia, severe symptomatic hyponatremia, hypermagnesemia, mild renal insufficiency, severe hyperkalemia, halide intoxication, preventing early acute renal failure, acute uric acid nephropathy
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What is the toxicity of loop diuretics?
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hypokalemia due to enhanced K excretion, ototoxicity
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What kind of drug is HCTZ?
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sulfonamide, inhibits Na transport in DCT
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What is HCTZ's MOA?
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inhibits Na transport in DCT (Na-Cl cotransporter)
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What transporter has a defect in Gitelman's Syndrome?
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Na-Cl cotransporter in DCT
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How is HCTZ excreted?
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filtration and secretion in urine
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How does HCTZ go systemically?
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absorbed in GI, binds to plasma proteins
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Why do you use HCTZ?
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hypertension, increases Na secretion, decreases SVR
hypercalciuria, increases Ca reabsorption, decreases rate of renal stone formation |
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What is HCTZ's toxicity?
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K loss, H loss with metabolic alkalosis, can precipitate gout, exacerbate hypercalcemia, can have hyponatremia
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What kind of drug is triamterene?
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inhibits Na in collecting tubules
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What kind of drug is amiloride?
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inhibits Na channel in collecting tubules
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What is the MOA of triamterene?
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inhibits Na channel in luminal membrane of late distal tubule, collecting tubule
decreases net NaCl reabsorption in collecting duct, hyperpolarizes luminal membrane and reduces lumen negative potential difference, K excretion inhibited |
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What is the MOA of amiloride?
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inhibits Na channel in luminal membrane of late distal tubule, collecting tubule
decreases net NaCl reabsorption in collecting duct, hyperpolarizes luminal membrane and reduces lumen negative potential difference, K excretion inhibited |
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What transporter is messed up in Liddle's syndrome?
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Na channel in luminal membrane of late distal tubule and collecting tubule
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How is amiloride eliminated?
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kidney
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How is amiloride absorbed?
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partially in GI tract
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How is triamterene absorbed?
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well from GI tract
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How is triamterene eliminated?
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renal excretion and metabolism
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Why do you use amiloride?
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diuretic, K sparing, often in combo with other diuretics, esp thiazides to eliminate K wasting
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Why do you use triamterene?
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diuretic, K sparing, often in combo with other diuretics, esp thiazides to eliminate K wasting
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What kind of drug is spironolactone?
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steroid analogue
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How does spironolactone work?
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competes with aldosterone for cytosolic receptor, doesn't increase mRNA syntehsis, prevents aldosterone from accelerating K excretion and reducing Na excretion
only works if aldosterone is acting |
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What are the pharmacokinetics of spirolactone?
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rapidly absorbed and metabolized
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Why do you use spironolactone?
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edema of cirrhosis, K sparing, CHF
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What is the toxciity of spironolactone?
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hyperkalemia, gynecomastia
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How do you give diuretics?
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determine effective dose, maintenance regimen
if lacks, add another MOA drug, find better treatment for primary disease |
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How do Carbonic Anhydrase inhibitors affect ions?
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Na +
FeNa 5 K + Ca + Mg - Cl 0 HCO3 ++ |
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How do thiazides affect ions?
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Na ++
FeNa 10 K + Ca - Mg + Cl ++ HCO3 + |
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How do loop diuretics affect ions?
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Na +++
FeNa 26 K + Ca ++ Mg + Cl +++ HCO3 0 |
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How do K sparing diuretics affect ions?
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Na +
FeNa <5 K - Ca - Mg - Cl + HCO3 + |
