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Pharmacology II > Cardiovascular: Diuretics > Flashcards

Cardiovascular: Diuretics Flashcards

1
Q

Definition of heart failure

A

inability of the heart to pump sufficient blood to sustain normal function

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2
Q

What causes heart failure?

A
  1. impaired cardiac muscle ability
  2. increase workload
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3
Q

How are RAS system activated?

A

reduced BP or volume causes stimulation of baroreceptor in the carotid sinus & aortic arch

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4
Q

What does RAS activation result in?

A
  1. incrreased sympathetic activity
  2. ADH release by hypothalamus
  3. retention of Na+ & water
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5
Q

What is preload?

A

volume of fluid in the heart prior to contraction

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6
Q

What does excess preload cause?

A

congestion (edema, ascite, hepatic congestion)

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7
Q

What is afterload?

A

pressure that the heart has to push against

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8
Q

What does excess afterload result in?

A
  1. mitral valve regurgitation
  2. decreased cardiac output
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9
Q

What are the pharmacological objectives to treat heart failure?

A
  • decrease preload
  • decrease afterload
  • alter heart contraction
  • decrease sympathetic input
  • address arrhythmia
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10
Q

How can preload be decreased directly?

A
  • decrease blood volume
  • increase venous capacity
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11
Q

How can the preload be decreased indirectly?

A
  • increasing fill time
  • increasing stroke volume/ cardiac output
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12
Q

What are the classes of drugs that can directly decrease preload?

A
  • diuretics
  • venodilator
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13
Q

Why does congestive heart failure lead to an increase in blood volume?

A

increased water & sodium retention

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14
Q

What happens during congestive heart failure?

A
  1. increased preload
  2. increased afterload
  3. increased vascular stiffness
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15
Q

Why does vascular stiffness occur during congestive heart failure?

A
  • Na+ accumulation in vascular smooth muscle
  • increased Ca2+ influx by Na-Ca exchanger
  • increased Ca2+ increases contraction of smooth muscle
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16
Q

What do diuretics do?

A
  • increase the volume and flow of urine; hence increasing the excretion of water
  • increase Na+ excretion
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17
Q

Why are diuretics commonly used to manage congestive heart failure?

A
  • directly decrease preload by decreasing blood volume
18
Q

What are some other uses for diuretics?

A
  • acute renal failure
  • increased intracranial/ intraocular pressure
    -increase excretion of toxin
19
Q

What type of diuretic is furosemide?

A
  • high-ceiling diuretic
  • loop diuretic
  • highly protein bound
  • excreted by renal tubule
20
Q

Mechanism of action of furosemide

A
  • inhibit Na+/Cl-reabsorption by inhibition of the Na/K/Cl co-transporter in the ascending loop of Henle
  • loss of Na+, Cl-, & water
  • increase synthesis of local prostaglandin that causes renal vasodilation
21
Q

Adverse effects of furosemide

A
  • dehydration & volume depletion
  • hypokalemia & hyponatremia
  • exacerbation of respiratory disease
22
Q

Contraindication of furosemide

A
  • digoxin interaction
  • NSAIDs
23
Q

Mechanism of action Thiazide diuretics

A
  • decrease permeability of distal tubule by inhibition of Na/Cl transporter in the distal convoluted tubule
  • decrease NaCl and water reabsorption
24
Q

What is Torsemide

A
  • loop diuretic with higher bioavailability & longer duration of action than furosemide
  • some aldosterone blocking effect to reduce chance of tolerance
25
Q

Clinical effect of Thiazide diuretics

A
  • increase Na+ and water elimination
  • increase K+ loss
  • increase Ca2+ absorption
  • mild direct vasodilatory effect
26
Q

How does Thiazide diuretics cause increase in Ca2+ absorption?

A

increase in extracellular Na leads to increased Na-Ca exchange;hence increase Ca reabsorption

27
Q

What is special about thiazide diuretics regarding diabetes insipidis?

A

paradoxically reduce urine production

28
Q

Adverse effects of thiazide diuretics

A

hypokalemia, hypercalcemia, hypotension

29
Q

Mechanism of action for spironolactone

A

competitive inhibitor of aldosterone & K+ sparing

30
Q

Special features of spironolactone

A
  • minimal diuretic effect
  • usually used in combination due to its K+sparing effect
31
Q

Contraindication for spironolactone

A

animals recieving ACE inhibitor or other K+ sparing diuretics

32
Q

What can result from giving spironolactone to animals receiving ACE inhibitor or other K+ sparing diuretics?

A

increase risk of hyperkalemia

33
Q

What are the beneficial effects that spironolactone provide

A

decrease heart remodeling

34
Q

Adverse effects of spironolactone

A

gastric upset, hyperkalemia

35
Q

What type of diuretic is mannitol?

A

osmotic diuretic

36
Q

Mechanism of action of mannitol

A
  • pharmacological inert sugar that remains in the lumen of the renal tubules to draw water out
  • small increase of Na/CL excretion
37
Q

Clinical indication for mannitol

A

used with acute renal failure, treat increased ocular & intracranial pressure

38
Q

Adverse effects of mannitol

A
  • extracellular water expansion (extracts water from cell)
  • hyper/hyponatremia ( water from cells dilute Na+)
39
Q

Carbonic anhydrase inhibitors mechanism of action

A
  • inhibit carbonic anhydrase in the proximal tubule, which decreases the intracellular H+
  • decreases the exchange of Na+ for H+, which limits Na+ reabsorption
  • decreases bicarbonate reabsorption
40
Q

Adverse effect of carbonic anhydrase inhibitor

A
  • metabolic acidosis
  • decrease in K+
41
Q

Indications for carbonic anhydrase inhibitor

A

glaucoma

Pharmacology II (8 decks)

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