EXAM 1 - DIURETICS Flashcards
What are the 7 classifications of diuretics
1.Inhibitors of carbonic anhydrase
2.Osmotic diuretics
3.inhibitors of NA, K, 2CL symport
4.Inhibitors of Na, Cl symport
5. inhibitors of renal epithelial Na channels
6. Mineralocorticoid receptor antagonists
7. vasopressin antagonists
where are inhibitors of carbonic anhydrase located
Proximal tubule (lumen surface)
Explain carbonic anhydrase inhibition
inhibit cytoplasmic CA and membrane-bound CA. By inhibiting it stops the reuptake of sodium bicarbonate
Why are CA inhibitors weak diuretics
These are weak diuretics because of the positioning of their target. Since these medications target the proximal tubule the water that is excreted is reabsorbed in distal parts of the nephron tube
Example of CA inhibitors
Acetazolamide (diamox)
Dichlorphenamide (daramide)
Methazolamide (Glauctabs)
Clinical use of CA inhibitors
Acute mountain sickness
metabolic alkalosis
Glaucoma
Urinary alkalinization
toxicities of CA inhibitors
Hyperchloremic metabolic acidosis
Renal stones
renal potassium wasting
Drowsiness/ paresthesia
Explain use and location of osmotic diuretics
Osmotic diuretics target the renal proximal tubule and descending limb because of their water permeable membranes. Theses diuretics shift the osmotic flow and blood flow which allows water to travel into the urine and lower the blood volume thus lowering blood pressure
Osmotic diuretics
IV
Mannitol
Urea
Oral
glucose
isosorbide
glycerine
explain the use and location of loop diuretics
these act on the luminal surface of the thick ascending limb on the Na, k, Cl symporter to block reuptake of sodium, potassium, chloride, and magnesium. These are the most powerful diuretics but also potassium wasting
Loop diuretics
Furosemide (lasix)
Bumetamide (Bumex)
Ethacrynic acid ( Edecrin) - must be metabolized first to be active
torsemide (Demadex)
Clinical use of loop diuretics
Edematous conditions
Acute pulmonary edema
Hypertension, heart failure
Acute hypercalcemia
Hyperkalemia
Acute renal failure
Anion overdose
Toxicities of loop diuretics
Dehydration
Hypokalemic metabolic
alkalosis
ototoxicity
hyperuricemia
hypomagnesemia
Explain use and location of thiazide and thiazide like diuretics
these target the sodium and chloride symport on the luminal surface on the distal convoluted tubule and it inhibit the reabsorption of potassium (potassium wasting)
Clinical use of thiazides
hypertension
heart failure
nephrolithiasis due to idiopathic hypercalciuria
nephrogenic diabetes insipidus
Toxicities of thiazides
hypokalemic metabolic alkalosis
hyperuricemia
impaired carbohydrates tolerance
hyperlipidemia
hyponatremia
Thiazides
chlorothiazides (diuril)
hypochlorothiazides (hydrodiuril)
chlorthalidone (hygroton)
metolazone (mykrox)
potassium-sparing diuretics use and location
Inhibit the renal epithelial sodium channel on the luminal surface of the late distal tubule and collecting duct
These are weaker diuretics and tend to be used in combination but they are potassium-sparing
Examples of potassium-sparing diuretics
Amiloride (dyrenium)
Triamterene (midamor)
Clinical use of potassium sparing
adjunctive treatment with thiazide or loop diuretics in heart failure or hypertension
Toxicities and contraindications of Potassium sparing
Hyperkalemia
Hyperchloremic metabolic acidosis
Contraindications - K supplements, ACE inhibitors
Mineralocorticoid receptor antagonists use and location
MRAs bind to the MR located in the late distal tubule and the collecting duct. When binding to MR it blocks the production on AIP which stops the reuptake of sodium thus reducing blood volume
MRA examples
Spironolactone (aldactone)
Canrenone
Potassium canrenoate
Eplerenone
MRAs clinical use and toxicities
Hypertension or HF w/other diuretics
mineralocorticoid excess
aldosteronism
toxicities - Hyperkalemia, hyperchloremic metabolic acidosis, gynecomastia,impotence, benign prostatic hyperplasia
Vasopressin antagonists use and location
targets a receptor located on the interstitial surface of the collecting duct cell and blocks the binding of vasopressin to the V2 receptor which through multiple cycles produces CAMP which thus activates protein kinase A to phosphorylate aquaporin channels that collect water from the lumen collecting duct to add water into the blood. So vasopressin antagonists stop the movement of water to to the blood serum to lower blood volume
Vasopressin examples
Conivaptan
tolvaptan
