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Flashcards in Diuretics Deck (50):
1

Classes of Diuretics

Cardiovascular Diuretics

Physiological Diuretics

Osmotic Diuretics

Loop (High Ceiling) Diuretics

Thiazide Diuretics

Potassium Sparing Diuretics

Carbonic Anhydrase Inhibitors

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Physiologic Diuretics

Not diuretic by definition, but have diuretic effect

3

Major effects of Alpha 1 adrenoceptors

Vasoconstriction

Increased peripheral resistance

Increased blood pressure

Mydrasis

Increased closure of internal sphincter of the bladder

4

Therapeutic uses of osmotic diuretics

Treatment of cerebral edema

Treatment of glaucoma

Treatment of acute renal failure

Mobilization of edema fluid

Used in patients with drug overdose

5

Examples of Carbonic Anhydrase Inhibitors

Acetazolamide

Methazolamide

Dorzolamide and Brinzolamide (Topical Ophthalmic)

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Adverse effects of Thiazide diuretics

Electrolyte imbalances

Hyperglycemia

Hypersensitivity reactions

Hyperlipidema

7

Most effective diuretics are

Loop diuretics

________________________________

Inhibit the most reabsorption of Na acting on ALoH

8

Diuretic efficacy of Spironolactone depends on

Levels of endogenous aldosterone

9

Pharmacokinetics of Triamterine and Amiloride

Admistered orally

Amiloride is excreted by the kidneys

Triamterene is convered to an active metabolite in the liver whihc is actively secreted in the urine

10

What osmotic diuretic is not metabolized and is elimiated rapidly by the kidney

Mannitol

11

Pharmacokinetics of Thiazide Diuretics

 

Administered orally

Absorption is slow and incomplete

Bind extensively to plasma proteins

Excreted maily by the kidneys and are actively secreted in urine by the organic acid secretory machanism

Decreased renal blood flow decreases their effectiveness

12

Glycerin and isosorbide are administered

Orally

13

Pharmacokinetics of Spironolactone

Administered orally

Readily absorbed and is highly bound to plasma protein

Extensively metabolized by the liver and is converted to an active metabolite

Onset of action is slow (2-3 days) and duration of action is long

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Diuretic

Medication that increases urine flow or urine volume

15

T/F: Diuretics are drugs that increase urination

False

16

Potency of diuretics depends on

Where it acts in the nephron

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Examples of physiologic diuretics

Water

Sodium Chloride

18

Therapeutic uses of Thiazide Diuretics

Treatment of edema of CHF, liver cirrhosis, nephrotic syndrome and acute glomerular nephritis

Treatment of hypertension alone or combined with other antihypertensive drugs

Treatment of nephrogenic diabetes insipidus and useful in central diabetes insipidus

Treatment of calcium nephrolithiasis and may be useful for the treatment of osteoporosis

Treatment of udder edema in cows

19

Duretics ranked from most effect to least effective

Loop Diuretics > Thiazide Diuretics > Osmotic Diuretics > Potassium Sparing Diuretics

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Adverse effects of carbonic anhydrase inhibitors

Mild systemic acidosis

Hypokalemia

Hyperglycemia

 

21

Mechanism of Action of Osmotic Diuretics

  1. Interfere with transport mechanisms in the thick ascending limb increasing the urinary excretion of Na, K, Ca, Mg, Cl, HCO3 and phosphate
  2. Osmotic effect in the tubule and reduce medullary tonicity
  3. Increase renal blood flow and renal medullary blood flow by several mechanisms

22

Mechanism of action of Loop or Ceiling Diuretics 

  1. Inhibit Na-K-Cl Symporter in the loop of henle
  2. Inhibits the paracellular reabsorption of Na, Ca, Mg
  3. Increased Na delivery to late distal tubule and collecting duct increases depolarization of the luminal membrane creating a lumen -negative transmembrane potentail difference - facilitates K excretion
  4. Stimulate Renin-Angiotension- Aldosterone
  5. Increases total renal blood flow
  6. Increase systemic venous capacitance

23

Therapeutic uses of Triamterine and Amiloride

Treatment of hypokalemia and hypomagnesemia

Occassionally used in edematous disorders and hypertension - very weak diuretics

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Mannitol and urea are administered 

IV

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Mechanism of action of Spironolactone

  1. Competitively blocks aldosterone binding to aldosterone receptor in the late distal tubule and collecting duct
  2. Excretion of NaCl and diuresis as well as retention of K and H

26

Major effects of Alpha 2 adrenoceptors

Inhibition of norepinephrine release

Inhibition of insulin release

27

Mechanism of Action of Thiazide Diuretics

  1. Inhibit the Na-Cl symporter in distal convoluted tubule - inhibition of tubular reabsorption of Na, Cl and diuresis
  2. Inhibit K and Mg reabsorption but increase reabsorption of Ca
  3. Cause hypokalemia and systemic alkalosis similarly to loop diuretics

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Examples of Loop or Ceiling Diuretics

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Therapeutic uses of Spironolactone

Diuretic

Treatment of primary and secondary hyperaldosteronism

30

Adverse effects of loop or ceiling diuretics

Ototoxicity

Hypokalemia

Hypomagnesemia

Acute hypovolemia

Hypotension

Cardiact arrhythmias

Hyperglycemia

Hyperuricemia

Systemic alkalosis

Hypersensitivity reactions

31

Pharmacokinetics of carbonic anhydrase inhibitors

Acetazolamide is administered orally

Onset of action is about 30 minutes and duration of action is 4-6 hours in small animals

Acetazolamide is eliminated maily by the kidneys and is actively secreted in urine by the organic acid secretory mechanism

Dorzolamide and Brinzolamide are administerd topically on the eye

32

Adverse effects of Spironolactone

Hyperkalemia

Systemic acidosis

Adverse effects on reproduction because it acts on progesterone and androgen receptors

33

Important Adrenoceptors

Alpha 1

Alpha 2

Beta 1

Beta 2

34

Adverse effects of Triamterine and Amiloride

Hyperkalemia

Systemic acidosis

35

Examples of Thiazide Diuretics

Hydrochlorothiazide

Chlorothiazide

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Therapeutic use of cardiovascular diuretics

Treatment of edema associated with congestive heart failure

37

Mechanisms by which Loop or Ceiling Diuretics contribute to hypokalemia and systemic alkalosis

  1.  K excretion through K channel in the luminal membrane of the principal cell and H secretion in type A intercalated cell into the lumen
  2. Stimulating the renin-angiotension-aldosterone

38

Examples of Potassium Sparing Diuretics

Spironolactone

Triamterene

Amiloride

39

General mechanism of action of all diuretics

Inhibit the reabsorption of Na

40

Examples of osmotic diuretics

Mannitol

Urea

Glycerin

Iso

41

Examples of cardiovascular diuretics

Digitalis 

Phosphodiesterase inhibitors

42

Pharmacokinetics of Furosemide

Administered orally and IV

Onset of action is rapid and duration is short

Partially metabolized by conjunction and partially excreted unchanged in urine and actively secreted in urine by the organic acid secretory mechanism

43

Cardiovascular Diuretics

Not a diuretic by definition, but have diuretic effect

Any drug that cause increased contractility/ cardiac output of the heart to have a diuretic effect due to increased renal blood flow

44

Osmotic diuretics act on what portion of the nephron

Act both on the loop of henle (primary site) and proximal tubule (secondary site)

45

Mechanism of action of Triamterine and Amiloride

  1. Block epithelial Na channels in the luminal membrane of the principal cells in the late distal tubule and collecting duct
  2. Excretion of Na and diuresis as well as retention of K and H

46

Therapeutic uses of carbonic anhydrase inhibitors

Treatment of open-angle glaucoma

Acetazolamide has been used in udder edmea

47

Therapeutic uses of loop or ceiling diuretics

Treatment of pulmonary edema and pulmonary congestion

Treatment of generalized edema associated with CHF, chronic renal failure and liver cirrhosis

Combined with isotonic saline to treat hypercalcemia and prevent volume depletion

May be used in patients with acute renal failure

Treatment of increased intracranial pressure and udder edema

Etc.

48

Major effects of Beta 2 adrenoceptors

Vasodilation

Slightly decreased peripheral resistance

Bronchodilation

Increased muscle and liver glycogenolysis

Increased release of glucagon

Relaxed uterine smooth muscle

49

Mechanism of action of carbonic anhydrase inhibitors

  1. Reversible inhibition of carbonic anhydrase (CA) which inhibits the exchange of hydrogen for sodium in the proximal tubule which is the primary site
  2. Secondary site is the collecting duct
  3. Carbonic anhydrase inhibitors lower intraocular pressure by inhibition of carbonic anhydrase in the eye decreasing formation of aqueous humor

50

Major effects of Beta 1 adrenoceptors

Tachycardia

Increased lipolysis

Increased myocardial contractility