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Pharmacology > Diuretics (Ex2) > Flashcards

Diuretics (Ex2) Flashcards

1
Q

What are diuretics?

A
  • drugs that increase the rate of urine flow and urine volume
  • also increase the rate of sodium excretion
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2
Q

What is the diuretic effect of Dopamine?

A
  • increases urination

- activation of dopamine receptors dilates renal vascular beds

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3
Q

What is the diuretic effect of Epinephrine and Norepinephrine

A
  • decreases urination
  • stimulates cardiac contraction using beta-1 receptors, leading to vasoconstriction of renal arteries, and decreased GFR
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4
Q

What is the diuretic effect of Isoprotenol?

A
  • an anti-diuretic

- beta-2 vasodilation, so not enough blood reaches the kidney

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5
Q

What are cardiovascular diuretics and what are they used for?

A
  • not technically diuretics, but their effects on the heart leads to diuresis
  • treatment of edema associated with congestive heart failure
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6
Q

What are some cardiovascular diuretic durgs?

A
  • Digitalis (digoxin)
  • Phosphodiesterase inhibitors: aminophylline, inamrinone, milrinone
  • Caffeine: methylxanthine
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7
Q

What are the two physiological diuretics, and what are they used in?

A

Water: expanded blood volume, so inhibition of ADH in collecting duct
- used in compensated chronic interstitial nephritis of dogs
Sodium chloride: used in urolithiasis in sheep, calves, and cats

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8
Q

Name 4 osmotic diuretic drugs

A
  • Mannitol
  • Urea
  • Glycerin
  • Isosorbide
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9
Q

Where do osmotic diuretics act?

How effective are they? (1st, 2nd, etc.)

A

Primary site: loop of henle
Secondary site: proximal tubule
3rd most effective

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10
Q

Explain the mechanisms of action of osmotic diuretics

A
  • interfere with transport mechanisms in thick aLOH, increasing urine excretion of Na, K, Ca, Mg, Cl, HCO3, and phosphate
  • osmotic effect in tubule, and reduce medullary tonicity
  • increase renal blood flow and renal medullary blood flow, which increases GFR
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11
Q

What are the therapeutic uses of osmotic diuretics?

A
  • treatment of cerebral edema
  • treatment of glaucoma
  • treatment of acute renal failure
  • mobilization of edema fluid
  • used in patients with drug overdose
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12
Q

Mannitol

Type of drug, use, contraindications

A
  • osmotic diuretic
  • used to treat localized edema
  • least likely to cause electrolyte imbalance
  • can cause hypokalemia which can result in arrhythmias
  • contraindicated in generalized edema
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13
Q

Explain the pharmacokinetics of the 4 osmotic diuretic drugs

A
  • mannitol and urea administered IV, because they are poor penetrators of membranes
  • mannitol is not metabolized, and is eliminated rapidly by the kidneys
  • glycerin and isosorbide are administered orally
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14
Q

What are 3 loop diuretics?

A

Furosemide
Bumetanide
Ethacrynic acids

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15
Q

Where do loop diuretics act?

How effective are they?

A

Ascending loop of henle

Most effective diuretics because 25% of Na is absorbed here

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16
Q

Explain the mechanism of action of loop diuretics

A
  • Inhibit Na-K-2Cl symporter in aLOH, also absorption of Mg and Ca
  • creates a lumen negative transmembrane potential difference, facilitating K+ excretion and H+ secretion, resulting in hypokalemia and systemic alkalosis
  • stimulates renin-angiotensin-aldosterone system
  • increases total renal blood flow
  • increases systemic venous capacitance (lowers blood pressure)
17
Q

What are the therapeutic uses of loop diuretics?

A
  • trtmt of acute pulmonary edema and congestion, generalized edema associated with CHF, renal failure, and liver cirrhosis
  • with isotonic solution to treat hypercalcemia and to prevent volume depletion
  • trtmt of increased intracranial pressure and udder edema
  • trtmt of exercise induced pulmonary hemorrhage in horses (furosemide)
  • used in drug overdoses
  • with hypertonic saline for severe hyponatremia
  • trtmt of edema of nephrotic syndrome
18
Q

Adverse effects of loop diuretics

A
  • ototoxicity
  • hypokalemia, hypomagnesemia, hypovolemia
  • hypotension
  • cardiac arrhthymias
  • hyperglycemia, hyperuricemia
  • systemic alkalosis
  • hypersensitivity to sulfonamides
19
Q

Explain the pharmacokinetics of Furosemide

A
  • administered orally and IV
  • rapid onset, short duration
  • partly metabolized by conjugation
  • partly secreted unchanged in urine
  • actively secreted in urine by the organic acid secretory mechanism
20
Q

What are 2 thiazide diuretics?

A
  • Hydrochlorothiazide

- Chlorothiazide

21
Q

Where do thiazide diuretics act?

How effective are they?

A
  • distal convoluted tubule

- 2nd most effective because 5% of Na is reabsorbed at the early distal tubule

22
Q

Explain the mechanism of action of thiazide diuretics

A
  • inhibit Na-Cl symporter in distal tubule
  • inhibits K and Mg reabsorption
  • increases reabsorption of Ca
23
Q

What are the therapeutic uses of thiazide diuretics?

A
  • trtmt of edema due to CHF, liver cirrhosis, nephrotic syndrome, and acute glomerular nephritis
  • trtmt of hypertension
  • trtmt of nephrogenic and central diabetes insipidus
  • trtmt of calcium nephrolithasis and possibly osteoporosis
  • trtmt of udder edema
24
Q

Adverse effects of thiazide diuretics

A
  • electrolyte imbalance (hyponatremia, hypokalemia, hypomagnesemia, hypercalcemia)
  • hyperglycemia
  • hypersensitivity to sulfonamides
  • hyperlipidemia
25
Q

Explain the pharmacokinetics of thiazide diuretics

A
  • administered orally
  • absorption is slow and incomplete
  • bind extensively to plasma proteins
  • excreted by kidneys, and secreted in urine by organic acid mechanism
  • decreased renal blood flow decreases their effectiveness
26
Q

What are 3 potassium-sparing diuretics?

A
  • Spironolactone
  • Triamterene
  • Amiloride
27
Q

Where do potassium-sparing diuretics act?

How effective are they?

A
  • Late distal tubule and collecting duct

- mild efficacy because only 2% of Na is reabsorbed here

28
Q

Explain the mechanism of action of Spironolactone

A
  • competitively blocks aldosterone binding to receptor in late distal tubule and collecting duct, resulting in excretion of NaCl, and retention of H and K
  • Efficacy depends on levels of aldosterone
29
Q

What are the therapeutic uses of Spironolactone?

A
  • as a diuretic

- trtmt of primary and secondary hyperalsoteronism

30
Q

What are the adverse effects of Spironolactone?

A
  • hyperkalemia
  • systemic acidosis
  • adverse effects on reproduction because acts on progesterone and androgen receptors
31
Q

Explain the pharmacokinetics of Spironolactone

A
  • administered orally
  • readily absorbed and highly bound to plasma proteins
  • metabolized by liver and converted to active metabolite
  • slow onset, long duration
32
Q

Mechanism of action of Triamterene and Amiloride

A
  • block epithelial Na channels in luminal membrane of principle cells in late distal tubule and collecting duct
  • this results in excretion of Na and retention of K and H
33
Q

Therapeutic uses of Triamterene and Amiloride

A
  • trtmt of hypokalemia and hypomagnesemia

- sometimes used in edematous disorders and hypertension

34
Q

Pharmacokinetics of Triamterene and Amiloride

A
  • administered orally
  • A is excreted by kidneys
  • T is converted to active metabolite in liver, then secreted in urine
35
Q

What are 4 carbonic anhydrase inhibitors?

A

Acetazolamide
Methazolamide
Dorzolamide
Brinzolamide

36
Q

Mechanism of action of Carbonic Anhydrase Inhibitors

A
  • inhibit carbonic anhydrase, which inhibits the exchange of H for Na in the proximal tubule and collecting duct (retains H)
  • lower intraocular pressure by inhibition of CA in the eye (decreasing aqueous humor formation)
37
Q

Therapeutic uses of carbonic anhydrase inhibitors

A
  • trtmt of open angle glaucoma
  • Acetazolamide used in udder edema
  • not used as diuretics
38
Q

Adverse effects of Carbonic Anhydrase Inhibitors

A
  • mild systemic acidosis
  • hypokalemia, hyperglycemia
  • vomiting, diarrhea, and hyperventilation in dogs
  • PU-PD
  • behavioral changes
  • pruritis of paws
39
Q

Pharmacokinetics of Carbonic Anhydrase Inhibitors

A
  • Ace is administered orally, eliminated by the kidneys, actively secreted in urine by organic acid mechanism
  • onset 30 min, duration 4-6hrs
  • Dorzo and Brinzo administered topically on the eye

Pharmacology (14 decks)

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