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Clinical Pharmacology > HTN: Diuretics > Flashcards

HTN: Diuretics Flashcards

1
Q

What is mannitol MOA? What are the clinical indications?

A

MOA: diuretic working on Proximal Tubule & Loop of Henle
- relative H2o diuresis

Indications:

  1. DEC ICP associated with cerebral edema**
    - maintain serum osm 310 to < 320
  2. GU irrigate in TURP or other transurethral surgical procedures**
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2
Q

How can mannitol increase plasma osmolality? Two mechanisms.

A
  1. Water diuresis leading to water deficit & hypernatremia

2. Hypertonic mannitol may be retained in AKI pts

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3
Q

What are the interactions and ADRs for mannitol and acetazolamide?

A

Interactions: anti-HTN & Vasodilators –> additive effective

ADRs

  • fluid/’lyte imbalance
  • hypovolemia* or dehydration secondary to rapid diuresis
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4
Q

What is acetazolamide MOA? What’s indication for use?

A

MOA: reversible inhibition of carbonic anhydrase
- produces both NaCl & NaHCO3 loss

Indication:

  1. prevention or amelioration of acute mountain sickness**
  2. edematous pt w/metabolic alkalosis - lose excess bicarb can restore acid-base
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5
Q

What’s the MOA of loop diuretics? Which drug is the big loop banger?

A

MOA: interferes with Na/K exchange in Thick Segment of Loop of Henle

Furosemide** (Lasix)

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6
Q

What are clinical indications for loop diuretics?

A
  • acute pulmonary edema & other edematous states**

- acute hypercalcemia**

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7
Q

What do you need to monitor for your pt on loop, thiazide diuretics?

A

BMP - first few weeks, then periodically

Ca & Mg - as needed

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8
Q

Why are loops better than thiazides for HF?

A

More Na excretion*

“double the dose until the urine flows”

  • if more is needed, add aldosterone AAG
  • if sxs persist, add thiazide
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9
Q

Besides HF, what else are loops better than thiazides at?

A

Loops work better than thiazides for GFR < 30**

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10
Q

How do loops impact calcium?

A

enhances calcium excretion –> improvement in hypercalcemia**

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11
Q

What are three things to know about Ethacrynic acid (loop) ?

A
  1. may be useful for pt who have not responded to other diuretics
  2. causes most ototoxicity
  3. only loop that is not a sulfonamide
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12
Q

There are 6 specific drug interactions of loop diuretics. What are they?

A
  1. NSAIDs antagonize diuretic effect** [via Na retention]
  2. Antagonizes DM meds** [via hypoK]
  3. Anti-arrhythmic toxicity [via hypoK]
  4. Li tox [DEC excretion]
  5. Antagonize gout meds [via urate reabsorption]
  6. Anti-HTN & VD [additive effect]
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13
Q

What are loop diuretic ADRs?

A
  1. Hypokalemia** / hypomagnesemia *
  2. Hyperglycemia** [hypoK involved in dysglycemia]
  3. Volume depletion [orthostatics, AKI]
  4. hyperuricemia
  5. SNHL “ringing”
  6. rash - sulfa
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14
Q

What are the three bolded thiazide diuretics?

A
  1. Hydrochlorothiazide
  2. Chlorthalidone
  3. Metolazone
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15
Q

What is the only thiazide available as IV?

Outside of knowing the IV, it is not really used clinically.

A

Chlorothiazide

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16
Q

What are thiazide MOA?

A

Interfere with K/Na exchange in Early Distal Convoluted Tubule

Effects of most thiazides is an overall DEC in SVR**

17
Q

Compare and contrast Chlorthalidone to Hydrochlorothiazide in terms of efficacy and general use

A

Chlorthalidone is 2x as potent w/a much longer duration of action (d/t creating a RBC “depot”)

Despite superiority of chlorthalidone, most fixed-dose combo that include a diuretic use HCTZ**

18
Q

Which is the main thiazide used in context of altered renal function [CrCl < 30]

A

Metolazone

  • other Thiazides are less effective with this renal level
19
Q

What effects may thiazide diuretics have on calcium?

A

All enhance Ca2+ reabsorption**

Improvement in hypercalciuria = DEC kidney stones **

May be beneficial in osteoporosis

20
Q

Which thiazide may be used with a loop diuretic for synergy in refractory edematous states?

A

Metolazone

21
Q

What are ADRs of thiazides?

A

Hypokalemia / hypomagnesemia –> hyperglycemia **

For the most part otherwise, at the low dose used for thiazides, you don’t really get many ADRs.
[The others listed are the same as loop diuretics]

22
Q

What is the unique thiazide ADR related to skin?

A

Increased risk of nonmelanoma skin CA w/HCTZ*

23
Q

There are two “classes” of K-sparing diuretics. List the class MOA and the two drugs for each class.

A
  1. Anti-aldosterone drug
    - MOA: antagonize mineralocorticoid receptors at Cortical Collecting Tubule –> DEC transcription of gene for Na/K ATPase
    - Spironolactone** and Eplerenone
  2. MOA: interferes with K/Na exchange
    - Amiloride** and triamterene
24
Q

What is the major difference between spironolactone and eplerenone in terms of action

A

Spironolactone - nonselective

Eplerenone - more selective for aldo than androgen and progesterone
- less gynecomastia and breast tenderness

25
Q

What is the clinical use of amiloride and triamterene?

A

Used with other diuretics to prevent or correct hypokalemia

Overall weak diuretic / BP lowering

Less use now as most diuretics combined with ACE/ARB

26
Q

What is the clinical use of spironolactone and eplerenone?

A

Mineralocorticoid excess

  1. Primary aldosteronism*
  2. Secondary aldosteronism**
    - HFrEF, hepatic cirrhosis, nephrotic syndrome
  3. Off-label
    - acne vulgaris, hirsutism
27
Q

As a class, what is the clinical use for Potassium-sparing diuretics?

A

Relatively weak natiuretic effect –> primarily used in combination with a loop or thiazide diuretic**

DEC degree of K loss or may INC net diuresis in pt w/refractory edema

28
Q

What monitoring is required with K-sparing diuretics? What are some C.I. values?

A

Don’t use for K > 5.5 or eGFR < 30

Monitoring
- K and BUN/Cr: baseline, w/in 1wk, monthly x3, quarterly for 1yr, then q 6mo

29
Q

What are the 3 main drug interactions with potassium-sparing diuretics?

A
  1. Avoid K supplements / salt substitutes
  2. Additive effect with Anti-HTN & vasodilators
  3. Careful with drugs retaining K
    - B-blockers
    - TMP-SMX
    - NSAIDs, ACE, ARB
30
Q

Class ADR of potassium-sparing diuretics?

A

Hyperkalemia

31
Q

What are the specific ADRs of spironolactone?

A
  1. Teratogen**
  2. Painful gynecomastia, amenorrhea
  3. ED, DEC libido
32
Q

What are the specific ADRs of triamterene?

A
  1. Potential nephrotoxin leading to crystalluria & cast formation (up to 50% of pt) **
33
Q

What is the benefit of using 2 diuretics?

A

Use of 2 drugs acting at different nephron sites may exhibit synergy**

Loops + thiazides produce more diuresis, than either alone

Metolazone + Loop usually used**

Clinical Pharmacology (54 decks)

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