Chap 15 - Diuretics Flashcards
In which part of the nephron do carbonic anhydrase inhibitors work?
Proximal convoluted tube
Where in the nephron do loop diuretics work? Be specific.
Thick ascending loop of Henle
Where in the nephron do thiazides work?
Distal convoluted tubule. (Early segment)
Where in the nephron do potassium sparing diuretics work?
Cortical collecting ducts.
Most diuretics work in the luminal side of the membrane with the exception of which?
Aldosterone receptor antagonist - these enter the collecting tubule cell from the basolateral side.
Which part of nephron is responsible for 60-70% of total sodium reabsorption?
Proximal convoluted tube
A hypokalemic state has what effect on pH? And a hyperchloremic state?
Increases and decreases respectively.
What is the difference between primary and nephrogenic diabetes insipidous?
N: can’t concentrate urine b/c kidneys not responding to ADH. P: can’t concentrate urine b/c not making ADH.
What is the class of diuretics that increase uric acid excretion, usually by inhibiting uric acid reabsorption? Example is ethacrynic acid.
Uricosuric diuretic.
What is the prototypic agent for the carbonic anhydrase inhibitors class of diuretics?
Acetazolamide
Which of the loop diuretics will make you acidotic? Alkalotic?( 2 each )
Carbonic anhydrase inhibitors and k+sparing drugs; loops and thiazides
Which of the diuretics gets rid of the most NaCl in urine? Of the most NaHCO3?
Loops and carbonic anhydrase inhibitors respectively.
Which of the diuretics has the dual effect of reducing intraocular pressure?
Carbonic anhydrase inhibitors hence they are used to treat severe acute glaucoma.
Which diuretic does the following: creates acidosis in CSF which results in hyperventilation which protects against high altitude sickness.
Carbonic anhydrase inhibitors.
Under what conditions will acetazolamide be used as a diuretic?
If edema and metabolic alkalosis is present.
Drowsiness, paresthesia, and formation of renal stones are common signs of toxicity for which class of diuretics?
CAi
At its most severe toxicity, this can lead to hepatic encephalopathy.
CAi, esp in pts with hepatic disease.
Which carrier is the target of loop diuretics?
Na+K+2Cl- carrier.
Approx what percent of sodium reabsorption is done in the TAL?
20 to 30
What is the prototypical loop agent?
Furosemide
Ethacrynic acid acts most like which of the diuretics?
Loops.
Diuresis of CAi is self-limiting and usually lasts how long? And what about the loops?
2 to 3 days. Short acting 4 hours done.
This class of diuretics is mainly used in tx of edematous states such as ascities and heart failure.
Loops
Why are loops no good for tx of HTN?
Too short acting
Otototoxicity is an important toxic effect of which agent?
Loops
The Na+Cl- transporter is the target for which agents?
Thiazides.
What is the prototype for thiazide diuretics?
Hydrochlorothiazide.
Is the duration of action of thiazides longer or shorter than loops?
Longer at 6-12 hours
What happens to urine calcium content with loop diuretics? With thiazides?
Increased. Decreased.
Thiazides plus what other diuretic will produce a synergistic effect with marked diuresis?
Loop
What is he major clinical application of use for thiazides?
HTN
The final segment of the nephron is the last site of Na+ reabsorption and is controlled by what?
Steroid hormone aldosterone.
The part of the nephron where reabsorption occurs via channels (ENaC) NOT a transporter.
Cortical collecting ducts
What is the primary site of acidification of the urine?
Cortical collecting duct.
To what class of drug does amiloride and triamterene belong?
Potassium sparing drugs
Aldosteronism is an important indication for which of the diuretics?
Spironolactone
Which diuretics should never be given with K+ supplements?
Potassium sparring diuretics.
Which of the diuretics can cause gynecomastia and anti-adrenergic effects?
K+ sparring (spironolactone)
What is the prototype for osmotic diuretics?
Mannitol
How exactly does mannitol work as a drug?
It is poorly reabsorbed (although freely filtered) and as a result it stays in the lumen and keeps water there with it. Remember, these work in the proximal tubule.
Which of the diuretics can also reduce brain volume and ITC pressure by osmotically extracting water from tissue in blood?
Mannitol. Note that a similar effect also happens in the eye and is used in treating glaucoma.
Which class of diuretics are mainly used to maintain high urine flow?
Osmotic drugs
Which class of diuretics are used to treat reduced BF?
Osmotic drugs.
Which class of diuretics does desmopressin belong to?
ADH agonists
Which class of drugs do conivaptan and tolvaptan belong to?
ADH antagonists
Which drug facilitates water reabsorption by activation of v2 recpetors?
ADH. Note that this action increases cAMP which leads to insertion of AQP2 water channels into luminal membrane.
Which diuretic drugs are used to treat pituitary diabetes insipidus?
ADH agonists
True or false: ADH agonists are useful in the treatment of nephrogenic diabetes insipidus.
False.
Which class of diuretics should be used to treat SIADH secretion?
ADH antagonists such as demeclocycline and conivaptan
What is the risk of toxicity with ADH?
In presence of large water load may cause hyponatremia.
What is the most toxic side effect of lithium?
Nephrogenic diabetes insipidus. FOR THIS REASON, NEVER USE TO TX SIADH. remember, lithium is an ADH antagonist.
