Diuretic Drugs Flashcards Preview

Pharmacology Quiz 4 > Diuretic Drugs > Flashcards

Flashcards in Diuretic Drugs Deck (16)
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1


Acetazolamide

List drug type, site, mechanism, indications, side effects...


Site 1 Diuretic: Carbonic anhydrase inhibitor, acts on proximal tubule. Decreases sodium-bicarbonate reabsorption in the proximal tubule, which results in more H+ and K+ ion excretion in the distal tubule. Can cause hypochloremic metabolic acidosis because of increased bicarbonate and K+ excretion (bicarbonate isn't recycled, leads to systemic acidosis).

Indications: glaucoma (decrease intraocular pressure), short term urinary alkalinization (excrete acid toxicants, dissolve some types of urinary crystals). Not good for long-term use because waning effect.

Side effects: calcium phosphate stones due to side effects of increased bicarb.

2

Carbonic anhydrase inhibitor actions

decrease sodium bicarb reabsorption in the proximal renal tubule and reduce formation of some transcellular fluids (aqueous humor)

not for long-term use

can lead to systemic acidosis

3


Loop Diuretics actions

Block Na/K/Cl cotransport in thick ascending limb of Henle's loop

example is Furosemide

4


Furosemide

List mechanism of action, type of drug

"Loop" Diuretic: Acts on site 2. Block NKCC2 transport proteins which inhibits Na/K/Cl cotransport in the thick ascneding limb of Henle's loop (counter-current exchange mechanism)

Increase Na+ delivery to the distal tubule, which can only partially resorb it, resulting in lots of the Na in the urine. Additionally decreases K+ recycling, reducing lumen electropositivity and reabsorption of Ca2+ and Mg2+ ions.

Net effect is hypertonic urine with lots of Na+, Cl-, K+, Mg++ and H+ in lots of water

5


Furosimide

route of administration, metabolism, site of action

given PO or parenterally

half undergoes phase 2 glucuronidation, half is excreted unchanged in urine

exhibits plasma protein binding, secreted into nephron

6


Furosemide Indications

(renal and one non-renal one in horses)

edema (rapidly decrease ECF volume), acute renal failure (increase urine flow and K+ excretion), toxicant ingestion (accelerate excretion), hyperkalemia, hypercalcemia, hyperthyroidism (I- secretion)

Also reduces exercise-induced pulmonary hemorrahage by decreasing blood volume

7


Furosemide in dogs

broad dose range, decrease BP, excrete NaCl and can possibly cause hypoglycemia

8

Furosemide in cats

narrow dose range, greatly decrease blood pressure, possible reversible otoxicitiy.

9

Furosemide adverse effects

hypokalemic metabolic alkalosis due to excretion of lots of K+ and H+

hypomagnesemia and hypocalcemia, dehydration, dilutional hyponatermia, ototoxicity leading to hearing loos esp if given with ototoxic drugs

10


Loop Diuretic drug interactions

Ototoxic drugs

NSAIDS- compete for transport into tubule

Glucocorticoids- enhance K+ depletion

Digitalis- hypokalemia increases activity and risk arrythmias

11

Hydrochlorothiazide

type, site, mechanism

Thiazide diuretic, acts on site 3 in early distal tubule to decrease salt reabsorption, Na + ends up being secreted.

Net effect is increased excretion of Na+, Cl-, K+, Mg++, H+ and water, and long-term increased Ca++ reabsorption.

Most NaCl and water is reaborbed before the early distal tubule so they are less effective.

 

12


Triamterene

type, site, mechanism, metabolism, elimination

Site 4 action, one of the K+ sparing diuretics

Directly blocks epithelial Na+ channels in principal cells of the late distal tubule and collecting duct, not dependent on aldosterone like spironolactone

short-term effects on normal K+ excretion

secreted into the proximal tubule, undergoes hepatic biotransformation to be converted to active metabolites, eliminated into urine, bind to plasma proteins

13

Spironolactone

Acts on site 4 as a K+ sparing diuretic

Antagonist of mineralocorticoid receptors and inhibits aldosterone-mediated induction of epithelail Na+ channels decreasing distal Na+ reaborption

Dependent on presence of aldosterone

Decrease K+ excretion

14


Indications and contraindications of site 4 diuretics (spironolactone and triamterene)

Indications: hypokalemia, edema secondary to hyperaldosteronism

Contraindications: hyperkalemia or hyperkalemic metabolic acidosis, disease states that mask K+ balance

Can be combined with a site 2 or 3 diuretic for natriuretic effects

15


Mannitol

Osmotic diuretics

Inhibits water reaborption (proximal convoluted tubule, descending tubule, and collecting duct) and disrupts renal counter-current exchange, net effect is increasing water excretion

Given IV and filtered at glomerulus with no reaborption, no metabolism, excreted in urine

16


Indications and Contraindications of Mannitol use

Indications: acute renal failure, toxicant elimination, cerebral edema, glaucoma, etc.

Contraindications: edematous states liek CHF or overexpansion of blood volume, pre-existing dehydration