Diuretics & RAAS Antagonists (complete) Flashcards Preview

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Flashcards in Diuretics & RAAS Antagonists (complete) Deck (22):
1

What is the site and MOA at the nephron for loop diuretics?

Loop of Henle (makes sense)
- Inhibits NaCl transport (Na+-K+-2Cl- transporter) in ascending Loop *IMPORTANT*
- This is where 25-30% of Na+ is reaborbed
- Increase Mg++, Ca++ excretion
- Increase renal blood flow
- Have GREATEST diuretic effect even if renal function is compromised

2

How are loop diuretics used in the treatment of heart failure?

- use w/ pts w/ volume overload
- effect enhanced w/ Na+ intake restrictions
- to ^ diuresis it's paired w/ thiazide

Also used in acute pulmonary edema, refractory edema, and hypercalcemia

3

What are the adverse effects of loop diuretics? Especially consider effects to plasma electrolytes

- Hypokalemic metabolic alkalosis (via enhanced K+ and H+ excretion)
- Hyperuricemia (^ risk to gout)
- Hypomagnesemia
- Hypocalcemia
- Ototoxicity
- Overdose => dizziness, HA, hypotension

4

What is the most commonly used loop diuretic?

Furosemide

5

What do you do if furosemide doesn't work? Think other loop diuretics

- ^ initial dose of furosemide
- Switch to bumetanide or torsemide
- admin via IV
- If sulfa allergy => ethacrynic acid

6

What is the site and MOA at the nephron for thaizides?

Distal convoluted tubule

- Inhibits Na+/Cl- cotransporter => increased urinary excretion of NaCl
- Modest diuretic effect (only 5-10% Na+ reabsorbed here)
- Increases reabsorption of Ca++

7

How are thiazides used in the treatment of heart failure?

- High doses needed than in HTN
- More efficacious diuretics usually required
- But can have synergistic diuretic effect w/ loop diuretics => useful in refractory edema

8

What are the adverse effects of thiazides? Especially consider effects to plasma electrolytes

- Hypokalemia
- Hyperglycemia
- Hyperuricemia (predisposed to gout)
- Hyperlipidemia (not good if pt has HTN)
- Volume contraction => hyperaldosteronism
- Allergies => skin rashes (sulfonamides)

9

What is a common type of thiazide used?

Hydrochlorothiazide

10

What is the site and MOA at the nephron for K-sparing diuretics, specifically aldosterone antagonists?

Collecting tubule (2-5% of filtered Na+ reabsorbed here)

- Competitive antagonist at aldosterone receptor
- Blocks synthesis of Na+ and K+ channels, Na+-K+-ATPase
- Mild diuresis => important in determining final urinary [Na+]

11

How are K-sparing diuretics, specifically aldosterone antagonists, used in the treatment of heart failure?

- Block aldo receptors on heart => RAAS antagonist
- Anti-remodeling action (bloc of aldosterone mediated cardiac hypertrophy/fibrosis)
- Raises serum K+ => no risk of hypokalemia

12

What are the adverse effects of K-sparing diuretics, specifically aldosterone antagonists? Especially consider effects to plasma electrolytes

- Hyperkalemia
- Endocrine abnormalities (gynecomastia w/ spironolactone) => blocks androgen receptor
- GI upset, drowsiness

13

Describe the renin-angiotensin-aldosterone system

- Renin converts angiotensinogen => angiotensin I
- ACE converts AI to angiotensin II

Ultimately increases BP via:
- vasoconstriction
- aldosterone secretion
- increased Na/H2O retention
- increased peripheral vascular resistance

14

Describe the contribution of chronic RAAS activation to the underlying pathology of HF

Chronic RAAS activation => exacerbates HF symptoms b/c of ^ BP and vasoconstriction

Also increases volume retention (this is what we target when using meds => OPTIMIZE FLUID RETENTION)

15

What is the target and MOA of ACEI?

- Targets ACE
- Inhibits ACE conversion of AI to AII
- Ultimately blocks AII-induced vasoconstriction => decreases preload and afterload
- Also prevents release of AII-induced aldosterone => decreases myocardial hypertrophy/remodeling

16

How are ACEI used in the treatment of HF?

- Decrease BP
- Decrease fluid retention
- Decrease hypertrophy/remodeling

17

Describe the adverse effects associated with ACEI, especially in relation to serum K+, renal function, and interactions w/ other drugs used in HF

- Hyperkalemia
- Hypotension
- Renal problems
- Chronic dry cough
- Category D in pregnancy (kills fetuses and such)

18

What is the most commonly prescribed ACEI?

lisinopril

19

What is the target and MOA of ARBs?

- Selectively inhibits AII receptor AT(1)
- Doesn't prevent formation of AII => just prevents its actions after it's made

20

How are ARBs used in the treatment of HF?

- More complete inhibition of AII than ACEI (b/c alternative pathways that form AII are NOT blocked by ACEIs)
- No cough, angioedema (no increased bradykinin levels)
- Used for similar reasons as ACEIs (decreased BP, vasodilation, etc.)

21

Describe the adverse effects associated with ARBs, especially in relation to serum K+, renal function, and interactions w/ other drugs used in HF

- Similar to ACEIs
- Hyperkalemia
- Hypotension
- Renal problems
- Contraindicated in pregnancy

22

What are commonly used ARBs?

- Valsartan
- Losartan