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Pharmocology- Unit Two
Diuretics (T Pierce)
57
Medical
Professional
09/14/2009

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Term
Example of CA inh.
Definition
acetazolamide
Term
Ex of thiazide diuretics
Definition

HTZ

chlorthalidone

metolazone

Term
Ex of loop/high ceiling diuretics
Definition

furosemide

bumetanide

Term
Example of Potassium sparring diuretics
Definition

spironolactone

amiloride

Term
Example of Osmotic diuretics
Definition
mannitol
Term
example of ADH antagonists
Definition
conivaptan
Term
types of secondary HTN
Definition
  • types
    • hyperAld
    • renal HTN
    • renovascular HTN
Term
pathophys. of renovascular HTN
Definition
  • stenosis of afferent renal A.
  • decrease renal perfusion pressure
  • activate RAAS
  • salt, water rention
Term
pathophys. of renal HTN
Definition
  • impaired renal excretion
  • leads to ECV expansion
Term
Plasma conc. of Ald, renin, and potassium in someone with hyperAld
Definition
  • high Ald
  • low renin
  • hypokalemia
Term
Effect of CA inh. on excretion of electrolytes: Na, K, H, Ca, Mg, Cl, HCO3 (note: we want effect on excretion, not plasma conc.)
Definition
  • Na- increase
  • K- MARKED increase
  • H- decrease
  • Ca- NO CHANGE
  • Mg- variable
  • Cl- increase
  • HCO3- MARKED increase
Term
Effect of CA inh. on RBF, GFR, TGF
Definition
  • RBF- decrease
  • GFR- decrease
  • TGF- increase
Term
Effect of osmotic diuretic on electrolyte excretion: Na, K, H, Ca, Mg, Cl, HCO3 (note: effect on excretion, NOT plasma levels)
Definition
  • Na- MARKED increase
  • K- increase
  • hydrogen- unknown
  • Ca- increase
  • Mg- MARKED increase
  • Cl- increase
  • HCO3- increase
Term
Effect of osmotic diuretic on RBF, GFR, TGF
Definition
  • RBF- increase
  • GFR- no change
  • TGF- unknown
Term
Effect of loop diuretic on electrolyte excretion: Na, K, H, Ca, Mg, Cl, HCO3 (Note: effect on excretion, NOT plasma levels)
Definition
  • Na- marked increase
  • K- marked increase
  • H- increase
  • Ca- marked increase
  • Mg- marked increase
  • Cl- marked increase
  • HCO3- increase
Term
Effect of loop diuretic on RBF, GFR, TGF
Definition
  • RBF- variable increase
  • GFR- no change
  • TGF- decrease
Term
Effect of thiazide diuretic on electrolyte excretion: Na, K, H, Ca, Mg, Cl, HCO3 (Note: effect on excretion, NOT plasma levels)
Definition
  • Na- increase
  • K- marked increase
  • H- increase
  • Ca- variable decrease
  • Mg- variable increase
  • Cl- increase
  • HCO3- increase
Term
Effect of sodium channel blocker on excretion of electrolytes: Na, K, H, Cl, Mg, Ca, and HCO3 (note: excretion, NOT plasma levels)
Definition
  • Na- increased
  • K- decreased
  • H- decreased
  • Ca- decreased
  • Mg- decreased
  • Cl- increased
  • HCO3- slight increase
Term
Effect of sodium channel blocker on RGF, GFR, TGF
Definition
  • RBF- no change
  • TGF- no change
  • GFR- no change
Term
Effect of thiazide diuretic on RBF, GFR, TGF
Definition
  • RBF- no change
  • GFR- variabe decrease
  • TGF- no change
Term
Effect of Ald. antagonist on excretion of electrolytes: Na, K, H, Ca, Mg, Cl, HCO3 (Note: excretion, NOT plasma levels)
Definition
  • Na- increase
  • K- decrease
  • H- decrease
  • Ca- unknown
  • Mg- decrease
  • Cl- increase
  • HCO3- slight increase
Term
Effect of Ald antagonist on RBF, GFR, TGF
Definition
  • RBF- no change
  • TGF- no change
  • GFR- no change
Term
Site of action of CA inh.
Definition
  • PCT (major)- major site of bicarb reabsorption
  • intercalated cells of CD

Can act anwhere CA is located (ex: gastric mucosa, RBC, eye)

Term
Mechanism of action of CA inh.
Definition
  1. inh. CA in lumen and epithelial cells
  2. reduce HCO3 reabsorption and decrease H secretion
    • creates acidosis
    • decreases production of aqueous humor
Term
plasma electrolyte levels of someone taking CA inhibitor
Definition
  • decreased HCO3, Na, K
  • increased Cl and H
    • lead to hypercholoremic acidosis (increased reabsorption of Cl into CD as result of increased negative driving charge from HCO3 in lumen)
  • increased CO2
Term
Therapeutic uses of CA inh.
Definition
  • second line treatment in open angle glaucoma (apply topically to the eye)
  • urinary alkalinization (enahnced excretion of weak acids, but if prolonged therapy, administer bicarbonate)
  • metabolic alkalosis (usually due to excessive loop/thiazide diuretic use)
    • esp. good in heart failure patients
  • acute mountain sickness- a form of respiratory alkalosis (prophylaxis)
  • epilepsy (given with antiepiletic medication)
    • metabolic acidosis slows down synaptic transmission
Term
Side effects of CA inhibitors
Definition
  • in large doses, drowsiness, paresthesia
    • decreased dose for elderly, renal failure patients
  • hypercholeremic metabolic acidosis
    • contraindicated in patients with COPD, hepatic cirrhosis
  • renal stones (calcium salts less soluble at alkaline pH of urine)
  • reduction in urniary excretion of weak organic bases (ex:NH3) due to increase pH
  • crosshypersensitivity with sulfonamides
Term
Mechanism of action of furosamide
Definition
  1. block Na/K/2Cl channel in TAL
  2. this will reduce the lumen potential
    • this leads to decreased Ca, Mg reabsorption
    • ABOLISH CORTICOMEDULLARY GRADIENT (we cant conc. the urine now)
  3. Also, block same channel in JGA
    • decrease renal vascular resistance
    • increased renal blood flow via PG action
  4. When given IV,
    1. dilate large veins, decreasing venous return
  5. acts as WEAK CA inh.
Term
Effect of loop diuretics on plasma electrolyte levels
Definition
  • hypochloremic alkalosis
  • hypokalemia
Term
therapeutic uses of loop diuretics
Definition
  • acute pulm. edema
  • edema of cardiac, hepatic or renal orgin that does not respond to thiazide
  • hyperkalemia, hypercalcemia
  • acute renal failure
    • increase urine flow and potassium excretion
Term
Routes of administration of loop diuretics and pharmacokinetics (DOA, time to action, metabolism and excretion percentage, how excreted)
Definition
  • orally absorbed
  • IV- act within five minutes
  • duration of action: 1-3 hrs (except torsemide which has a loner half life)
  • 60% excreted in the urine, the rest is metabolized
  • extensively bound to plasma protein and secreted by organic acid transporter
Term
Side effects of loop diuretics
Definition
  • fluid/electrolyte imbalance
    • hyperuricemia
    • hypokalemia
    • hypomagnesemia
    • hypochloremic alkalosis
  • cardiac arrhythmias
    • contraindicated with quinidine, leads to development of vent. tachycardia (torsades de pointes) which are fatal if hypokalemia present
  • hypotension (due to volume depletion)
  • ototoxicity (esp. ethacrynic acid)
  • hypersensitivity reaction in those allergic to sulfonamides (for furosamide is a sulfonamide)
Term
Mech of action of thiazide diuretics
Definition
  1. act at DCT to inhibit Na/Cl cotransporter
    1. no effect on corticomedullary gradient
Term
Effect of thiazide diuretics on plasma conc.
Definition
  • hypokalemia
  • hypochloremic alkalosis
Term
Effect of thiazide diuretics on urine excretion of electrolyties
Definition
  • increased excretion of:
    • Na
    • Cl
    • K
  • decrease excretion of calcium

Hyperosmolar urine

Term
Therapeutic uses of thiazide diuretics
Definition
  • HTN (reduce volume, mild vasodil)
  • CHF
  • hypercalciuria (prevents renal stones)
  • nephrogenic diabetes insipidus (thiazides can substitute for ADH)
Term
Side effects of thiazide diuretics
Definition
  • fluid and electrolyte imbalance
    • hyponatremia
    • hypochloremic alkalosis
    • hypokalemia
    • hypercalcemia
    • hyperuricemia
    • cardiac arrhythmias
  • hypotension due to volume depletion
  • hyperglycemia
  • increase LDL, total chol., total triglyc.
  • hypersensitivity rxn
Term
Mech. of action of spironolactone and eplerenone
Definition
  1. act at collecting duct to compete with Ald for binding to its receptor
  2. spironolactones active metabolite, canernone, forms an inactive receptor complex, block Ald action
    • without circulatin Ald, there can be no effect
    • eplerenone is more selective than spironolactone, so less side effects
Term
Effect of Ald R blockers on plasma and urine
Definition
  • plasma- hyperkalemia
  • urine
    • increase excretion of Na, Cl, water
    • decreased excretion of K
Term
pharmacokinetics of Ald R blockers
Definition
  • take hours to days to reach peak effect
  • absorbed orally and induce cyc P450
Term
Ald R blockers are given in conjunction with what drug(s)? Why
Definition
  • either thiazide or loop diuretics
  • prevents some K excretion which would occur with the thiazide, loop diuretics
Term
therapeutic uses of Ald R blockers
Definition
  • primary hyperAld
  • secondary hyperAld resultin from CHF, hepatic cirrhosis, nephrotic syndrome
Term
Side effects of Ald R blockers
Definition
  • hyperkalemia
    • more at risk if use drug that suppresses RAAS (ex: ACE inh.)
    • must monitor K levels if use both ACE inh. and Ald R blocker
  • gynecomastia in males
  • menstrual irregularities in females
Term
Mechanism of action of triamterene and amiloride
Definition
  1. act at CD to block sodium channels, leading to decrease Na/K exchange
    • INDEP. OF ALD PRESENCE
Term
Effect of triamterene and amiloride on urine and plasma electrolyte levels
Definition
  • urine- decreased K excretion
  • plasma- hyperkalemia
Term
Therapeutic uses of triamterene and amiloride
Definition
  • given in conj. with thiazide and loop diuretics
  • this will prevent loss of K
Term
Pharmacokinetics of triamterene and amiloride
Definition
  • bound to plasma proteins and secretd by organic base transporters in PCT
Term
Side effects of triamterene and amiloride
Definition
  • hyperkalemia (esp. in presence of renal disease)
  • triamterne can precipitate in urine causing kidney stones
    • contraindicated with use of indomethacine (cases of acute renal failure)
Term
Osmotic diuretics mechanism of action
Definition
  1. mannitol is a nonelectrolyte that is freely filterable at the glomerulus and poorly reabsorbed by the renal tubule
  2. mannitol acts at segments in tubule permeable to water (PCT, DCT, tDL, CD)
    1. increase osmotically active solute in filtrate, leading to decrease water reabsorption, causing increased urine volume
    2. increase renal blood flow, leading to decrease in corticomedullary osmotic gradient, which will decrease reabsorption of water from tDL and CD
Term
Effect of mannitol on urine and plasma
Definition
  • urine
    • increase in volume
    • decrease in osmolality
    • increase electrolyte excretion due to:
      • lowered tubule sodium conc.
      • increased tubular flow rate
  • plasma
    • initially produce hyponatremia due to transfer in fluid to extracellular compartment
    • however, since water diuresis with mannitol is greater than increase in natriuresis, this can cause hypernatremia
Term
therapeutic uses of mannitol
Definition
  • maintain urine flow in prophylaxis and treatment of acute renal failure
  • short term reduction in intracranial or intraocular P before and after surgery
  • acute glaucoma attacks
  • dialysis disequilibrium
    • reduce hypotension and CNS symtpoms after over dialysis (decreased plasma osmolality)
Term
Side effects of mannitol
Definition
  • before diuresis, increase ECV lead to pulm. edema and CHF
  • initial hyponatremia, cause headache, nausea, vomitting
  • prolonged mannitol use without water replacment causes:
    • dehydration
    • free water losses
    • hypernatremia
    • hyperkalemia
  • contraindicated for active cranial bleed
Term
Mechanism of action of conivaptan
Definition
  • act at collecting duct basolateral membrane by blocking ADH receptors (V1a and V2)
Term
Effect of conivaptan on plasma and urine
Definition
  • urine- increased volume and decrease osmolality
  • plasma- increased sodium concentration
Term
Therapeutic uses of Conivaptan
Definition
  • SIADH (only IV preps available)
  • CHF when increased ADH levels present
Term
Side effects of conivaptan
Definition
hypernatremia
Term
Route of administration of mannitol
Definition
not absorbed orally and must be given IV
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