Diuretics

Question 1

Diuretics (general)

Answer 1

increase Na and water excretion of kidneys–>decrease blood volume–>decrease blood pressure
Requires routine serum electrolyte monitoring

Question 2

Diuretics (types)

Answer 2

thiazides
loops
potassium sparing
aldosterone antagonist/mineralcorticoid receptor antagonist

Question 3

Diuretics (where do they work)

Answer 3

Loops (loop of henle/thick ascending loop)
Thiazides (distal convoluted tubule)
Aldosterone antagonists (collecting tubule)

Question 4

Thiazides

Answer 4

hydrochlorothiazide
chlorthalidone
metalozone
indapamide

Question 5

Thiazides (general)

Answer 5

Treat HTN (JNC 8 & ASH rec)
Significantly decrease BP, better outcomes
Often used in combos
Not enough diuresis for edema/HF
Not effective if GFR <40 (except metalozone with loops)

Question 6

Thiazides (AE)

Answer 6

Hypo K/MG
Hyper uricemia/glycemia/lipidemia
diuresis

Question 7

Thiazides (Caution)

Answer 7

decreased renal function with age

if increased risk for metabolic effects (inc uric acid, insulin resistance)

Question 8

Thiazides (dosing)

Answer 8

Max chlorathalidone 25mg daily (1.5-2x more effective than HCTZ for BP)
Max HCTZ 25-50mg daily
Dose AM

Question 9

Thiazides (drug interactions)

Answer 9

Steroids: Na retention, antagonize thiazide
NSAIDs: blunt thiazie response
Class Ia/III antiarrhythmia with prolong QT: torsades de pointes with hypoK
Prebenacid, lithium: interfere with thaizde excretion, block effect
Lithium: decrease lithium clearance, increase risk of toxic
Digoxin: hypkalemia, increase risk of toxic

Question 10

Loops (general)

Answer 10

Good at diuresis, not great for HTN, works fast
Diuresis not limited by dehydration (can overdiurese)
MOA: blocks Na/Cl re-absorption at loop of henle (usually 35-45% of filtered solution),
Decreased renal vasuclar resist/increased flow
Works even with poor renal function

Question 11

Loops

Answer 11

Furosemide
Torsemide
Bumetanide
Ethacrynic acid

Question 12

Loops (bioavailability)

Answer 12

Oral bioavailability: 100%(torsemide, bumetanide), 50% (furosemide)
Slight delay of effect if given orally, work within minutes if IV
1/2 dose of IV furosemide=1 dose oral
1 dose IV bumetanide, torsemide=1 dose oral

Question 13

Loops (dosing)

Answer 13

Start low, titrate up; taper cautiously
Goal up to 2lbs loss/day until euvolemic
AM dose
May have patient self-adjust to prevent overuse/AE

Question 14

Loops (ceiling dose)

Answer 14

Max effect due to compensatory increase in Na absorption in distal and proximal tubules
Increase frequency, continuous infusion, combo with thiazides to increase effect

Question 15

Loops (AE)

Answer 15

HypoK/Mg/Ca (may result in cardiac dysrhythmias)
Excessive diuresis (hypoNa, low BP, renal insufficiency)
Reflex activation of RAAS
Hypouricemia
Renal damage (esp with ACE-I/ARB)

Question 16

Loops (interactions)

Answer 16

Aminoglycosides (ototoxicity)
NSAIDS (blunt response)
Class Ia/III antiarrhythmia with prolong QT (torsades de pointes with hypoK)
Probenacid (blocks effect by interfering with excretion in urine)
Any drugs that aggravate hyperglycemia/uremia, dyslipidemia
ACE-I/ARB (monitor kidney function!)

Question 17

Loops (monitor)

Answer 17

Electrolytes
Kidney function (CrCl, GFR)

Question 18

Potassium sparing (general)

Answer 18

MOA: inhibit Na transport at late distal/collecting ducts (NOT mineralcorticoid receptors)
Use wit loops/thiazides to reduce K+ loss
Modest diuresis
Dose AM

Question 19

Potassium sparing

Answer 19

Amiloride

Triamterene

Question 20

Potassium sparing (AE)

Answer 20

HyperK

Question 21

Potassium sparing (Interactions)

Answer 21

ACE-I (up risk of hyperK)
Indomethacin (decrease renal function with triamterene)
Cimetidine (up bioavail, decrease clearance of triamterene)

Question 22

Potassium sparing (monitor)

Answer 22

Renal function

Electrolytes (K+)

Question 23

Aldosterone antagonists (general)

Answer 23

AKA Mineralocorticoid receptor antagonists
Type of postassium sparing diuretic
MOA: antagonize aldosterone receptors, modulate vascular tone, cause diuresis, increase NaCl excretion, decrease K+ excretion
Diminish cardiac remodeling in HF
Good for resistant HTN (w/ or w/o primary aldosteronism)

Question 24

Aldosterone antagonist

Answer 24

Spironolactone

Eplerenone

Question 25

Aldosterone antagonist (dosing)

Answer 25

Start spironolactone 12.5-25mg (alt days if renal problems)
Start eplerenone 25mg daily (up to 50mg, halve dose/alt days if CrCl <50mL/min)

12.5-50mg/day (low dose but significant BP drop) ADDED to diuretic+ACE-I/ARB
May use in combo with loops/thiazides to decrease loss of K+

Question 26

Aldosterone antagonist (AE)

Answer 26

HyperK
Gynecomastia/breast tenderness (esp spironolactone)
Menstrual irregularities
Hirsutism

Question 27

Aldosterone antagonist (cautions)

Answer 27

Elderly patients with diabetes
DO NOT USE if K+> 5.0mEq/L, CrCl<30mL/min, SCr>2.5mg/dL
STOP/reduce if K+> 5.5mEq/L, worsened renal function
Decrease/stop K+ supplements, avoid high K+ foods

Question 28

Aldosterone antagonist (interactions)

Answer 28

ACE-I, ARB, NSAIDs (increase hyperK)
Digoxin (increase plasma concentration of spironolactone)
K+ supplements (increase hyperK, don’t use if K+>3.5mEq/L)
CYP3A4 inhibitors (increase plasma concentration and effects of eplerenone)

Question 29

Aldosterone antagonist (monitor)

Answer 29

Electrolytes (check baseline and within 1 week start/titrate)