Diuretics and RAAS Antagonists Use in Heart Failure Flashcards Preview

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Flashcards in Diuretics and RAAS Antagonists Use in Heart Failure Deck (56):
1

HF Pharmacotherapy Goals

1) Reduction of Congestion- Diuretics
2) Modulate Neurohormonal activation- RAAS antagonists and B-Blockers- Positive Remodeling
3) Improve flow- Vasodilators (difficult to obtain pharmacotherapeutically)

2

Chronic HFrEF Treatments

BB
ACEI/ARB
Aldosterone antagonist
Hydralazine / ISDN
+/- Digoxin
ICD/CRT

3

Chronic HFpEF Treatments

Unknown
Control Risk Factors (DM, HTN, obesity)
Control volume status

4

Acute HFrEF Treatments

No standard treatment
IV Diuresis
Nitrates (if BP allows)
CPAP (if SOB)
Pressors (if very depressed cardiac output/shock)

5

Acute HFpEF Treatments

No standard treatment
IV diuresis
Nitrates (if BP allows)
CPAP/BiPAP

6

Preferred Type of Diuretics. Reason. Specific Drugs.

Loop Diuretics are preferred because of EFFICACY. Can be augmented with a thiazide diuretic. Used Chronically and acutely. Furosemide (lasix) is the most common. Torsemide and bumetanide have more reliable absorption.

7

ACEIs.

Produce vasodilation and decreased aldosterone activation
Plus antiremodeling effect

8

ARBs. Use?

Used in patients intolerant to ACEIs (most often cough due to Bradykinin breakdown product)

NO apparent benefit from dual therapy with ACEI and ARB

9

Aldosterone Antagonists. Use and functions?

Added to therapy for LVEF < 30-35%, optimized on ACEI/ARB and β-blocker therapy. Blocks aldosterone effect on kidney. Antiremodeling action plus produces additional Na+ loss at the kidney.


10

Diuretics (we need to know).

Hydrocholothiazide
Furosemide (Lasix)
Spironolactone (Aldactone)

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Diuretic general location of action and mechanisms.

Exert effects at lumenal (urine) surface of renal tubule cells.
Work by:
1) Interactions with membrane transport proteins (thiazides, furosemide)
2) Interactions with enzymes (acetazolamide) or hormone receptors (spironolactone)
3) Osmotic effects preventing water reabsorption (mannitol)

12

Na+ movement is controlled by?

Na+-K+ ATPase activity at the interstitial (blood) surface. In the kidney, Na+-K+-ATPase produces gradient necessary for Na+ reabsorption from the urine back into the blood. No diuretics work against the Na-K-ATPase.

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Loop Diuretic Example(s)

Furosemide (variable bioavailability)

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Potassium Wasting Agent(s)

Loop Agents
Thiazides

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Potassium Sparing Agent(s)

Aldosterone Antagonists

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Furosemide Blocks...? Causes increased excretion of...?

NKCC2. Na-K-Cl Cotransporter. Decreases Sodium transport across membrane (Urine to Blood). Also, decreases potassium transport back into Urine (decreased membrane potential) which blocks magnesium and calcium transport. Leads to increased H20 excretion as well.

17

TAL

Thick Ascending Limb of Loop of Henle

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Loop Diuretics effect on blood flow and diuretic effects on patients with decreased renal function.

Increase renal blood flow via effect on renin-angiotensin and prostaglandin systems
Retain substantial diuretic effect even if renal function is compromised (CrCl < 50 ml/min)
Handled by glomerular filtration and renal secretion

19

Loop Diuretics Use? Enhanced by?

-Used in HF patients with volume overload to eliminate symptoms of fluid retention
-Efficacy is enhanced with salt restriction (< 2 g/day)

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Pt's with HF have reduced.....

Diuretic Response! Decreased drug delivery to kidney via decreased RBF. Hypoperfusion activates of RAAS and SNS.

21

Most common use of a thiazide

Refractory Edema! Synergistic effect with Loop Diuretics.

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Thiazide Purpose

Block distal tubule sodium reabsorption

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Aldosterone Antagonist Improves? Functions?

Improves survival of some patients with HF. Enhances diuresis and ameliorates the potassium wasting at the collecting tubule (CT)

24

Most efficacious diuretic in HF?

LOOP DIURETICS!! (High-ceiling dose drug)

25

LD's Adverse Reactions

Hypokalemic metabolic alkalosis (predisposes to ectopic pacemakers and arrhythmias)
Hyperuricemia (may precipitate a gout attack)

26

Loop and Thiazide Potassium effect?

Synergistic Potassium excretion!

27

Thiazides block

NCC cotransporter (Na and Cl). Decreases Sodium transport (increased excretion) and increased Ca2+ reabsorption (decreased serum Ca2+ levels). MODEST diuretic effect (only 5 to 10% of Na is reabsorbed at the distal tubule).

28

Methods to increase loop diuretic efficacy?

-Increase initial dose of furosemide
-Switch to bumetanide or torsemide = more reliable bioavailability and longer duration of action
-IV administration may be required initially due to congestion-related interference with oral absorption

29

ACEI Dosing Timeframe?

Started during or after optimization of diuretic therapy
Initiated at low doses and titrated to goal

30

Aldosterone Antagonist Monitoring? Specific drugs?

Monitor for Hyperkalemia and kidney function.

Spironolactone preferred if tolerated - if endocrine side effects occur, Eplerenone can be used.

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Prototypical Thiazide and dose

Hydrochlorothiazide
once or twice daily dose

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Thiazide Adverse Reactions

Hypokalemia- predisposition to ectopic pacemakers!
Hyperuricemia- avoid in patients with gout
Hyperglycemia
Hyperlipidemia
2° hyperaldosteronism
Allergic reactions: skin rashes occasionally, related to SULFONAMIDE STRUCTURE!

33

Aldosterone Signal?

Decreased Blood Volume

34

Aldosterone Effects?

Receptor increases concentration of ENaC (channels) in lumenal membrane and Na/K ATPase in interstitium membrane.

35

Aldosterone Antagonist Blocks...?

Binds Aldosterone receptor, blocks activity and decreases Na/Fluid reabsorption. MILD diuretic effect (only 2-5% Na reabsorption at collecting duct)

36

Benefit of Eplerenone over Spironolactone?

Decreased Gynecomastia (no man boobs!). Lower affinity for androgen and progesterone receptor.

37

Triamterene/Amiloride

NO UTILITY IN HF! direct block of Na channels in collecting duct.

38

Spironolactone/Eplerenone Dosing

1-2 doses/day for both. Must wait for turnover of receptors to become effective.

39

Most important action of Spironolactone in HF is?

Block of aldo receptors on heart- acts as a RAAS antagonist rather than a diuretic. ANTI-REMODELING action (decreased hypertrophy and fibrosis)! Also, increases potassium to counter arrhythmias from K+ wasting diuretics.

40

K+ sparing diuretic adverse reactions

1) Hyperkalemia- EKG changes, conduction abnormalities, arrhythmias. Increased risk with age, underlying renal dysfunction, higher dosage, use with ACEI/ARB and usage of NSAIDS.

2) Endocrine Abnormalities (gynecomastia) with spironolactone via block of androgen receptor (not with eplerenone)

41

Targets of RAAS antagonists

AT-1 receptor, ACE, and Aldosterone receptor.

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ACE produces?

Angiotensin II from Angiotensin I and inactivates Bradykinin (may cause vasodilation)

43

ACE effects?

AT-1 @ vessels produces vasoconstriction. AT-1 @ kidneys produces increased aldosterone.

44

Breakdown of Bradykinin may result in?

Cough!

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ACEI's vs ARBs

Same effects but cough won't occur w/ ARBs. (Pril to Sartan with cough). Both RAAS antagonists. Elevated Potassium with both!

46

Vasodilators vs ACEIs

Vasodilators have less survival benefits than ACEIs in HF.

47

ACEI/Aldosterone blockers Effect in HF

Moderates myocardial hypertrophy and remodeling

48

ACEI Bradykinin Effect

Decreases bradykinin inactivation, increasing its vasodilator action

49

ACEI Prodrug Examples and Mechanism

lisinopril and captopril. De-esterification in liver to active metabolite.

50

ACEI Potential Side Effects

Hyperkalemia
Hypotension
Decreased Renal Function
Chronic Dry Cough
CATEGORY D DURING PREGNANCY!

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Positives of ARBs vs ACEIs

1) More complete inhibition of Ang II (not all pathways are blocked by ACEIs)
2) No side effects due to increased Bradykinin levels (cough, angioedema)

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Negatives of ARBs vs ACEIs

1) Loss of increased BK vasodilation seen with ACEIs
2) Only Ang II actions at AT-1 receptors are blocked

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ARB Dosing

Once daily dosing (except losartan x 2 daily)
Decreased losartan dose necessary in hepatic dysfunction

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ARB Side Effects

Similar to ACEI, contraindicated in pregnancy
NO angioedema or cough, which are thought to be bradykinin-mediated

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Thiazide Example(s)

Hydrochlorothiazide

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Aldosterone Antagonist Example(s)

Spironolactone and Eplerenone