Diuretics Flashcards
As a class, Diuretics are used in the management of:
Edema
Hypertension
Cardiovascular and/or renal disease
Glaucoma
These drugs all act in the nephron to cause
diuresis
diuresis
Increased urine production
Classes of diuretics
Thiazide–Hydrochlorothiazide
Loop–Furosemide
Potassium-Sparing–Spironolactone, triamterene
Osmotic–Mannitol
Carbonic Anhydrase Inhibitors–Acetazolamide, dorzolamide
MOA of hydrochlorothiazide
Hydrochlorothiazide (HCTZ)
MoA: Inhibition of the Na+,Cl- symporter in the early portion of the distal tubule, which leads to a decreased resorption of these ions.
Increases sodium and water excretion
HCTZ is used in the treatment of
Used in the treatment of HTN,
diabetes insipidus,
nephrolithiasis
ADR of HCTZ:
hypotension, dizziness, hypokalemia, hyponatremia, increased blood glucose The hypokalemia can bring about metabolic alkalosis and reduced insulin secretion (hyperglycemia)
“Sulfa allergy”—the presence of a sulfonamide functional group in a drug molecule can trigger an anaphylactic response in some patients
drug interactions of HCTZ
potentiates the effect of loop diuretics.
hypokalemia exacerbates digoxin toxicity
Loop diuretics
Furosemide
Mechanism of action of loop diuretics
Inhibition of the Na+,K+,2Cl- symporter in the ascending limb of the loop of Henle.
Increases sodium and water excretion…more so than other diuretics
loop diuretics is used in the treatment
Used in the treatment of cirrhosis,
HF,
hypercalcemia,
pulmonary edema, and renal disease
ADR of loop diuretics
ADRs include: hypotension, dizziness, hypokalemia, hyponatremia, hypocalcemia, (reversible) ototoxicity
The hypokalemia can bring about metabolic alkalosis
“Sulfa allergy”
Drug interactions of Loop diuretics
Drug Interactions: hypokalemia can exacerbate digoxin toxicity,
hypotensive effects synergistic with other anti-hypertensives
potassium sparing diuretics
Amiloride,triamterene,spironolactone
Amiloride and triamterene MOA
MoA: Sodium channel blockers preventing reabsorption at the late distal tubule and collecting duct, which indirectly reduces the secretion of potassium into the tubular filtrate and urine
Spironolactone
MoA: Aldosterone antagonist at the late distal tubule and collecting duct, which blocks gene expression ultimately prevents sodium reabsorption and potassium secretion
potassium sparing drugs are used in the treatment of
These drugs are used to treat or prevent hypokalemia
ADR of potassium sparing drugs
ADRs include: hypotension, dizziness, hyperkalemia
Spironolactone has an antiandrogenic effect, and can cause gynecomastia and impotence in men.
Drug interactions of Potassium sparing drugs
Drug Interactions: Administration with ACE inhibitors, ARBs, or potassium supplements can cause hyperkalemia
Osmotic diuretics
Mannitol and Glycerol
Mannitol route of administration (ROA)
IV
Glycerol ROA
PO
Osmotic diuretics MOA
They are filtered in the glomerulus
They are not reabsorbed from renal tubule
they osmotically attract water
they retain water in the nephron and in the urine
They also increase the osmotic pressure in the interstitial and trans cellular fluid.
Osmotic diuretics are used in the treatment of
cerebral edema
acute renal failure
Acute Glaucoma
ADR of osmotic diuretics
increase in plasma volume
exacerbation of heart failure
edema
Drug interactions
potentiates the effect of other diuretics
Carbonic anhydrase inhibitors
Acetazolomide and dorzolomide
MOA of CAI
These drugs inhibit carbonic anhydrase (CA) throughout the body.
CA is required for reabsorption of sodium bicarbonate from the proximal tubule, thus its inhibition alkalinizes the urine and produces mild diuresis.
These drugs are rarely used as diuretics
ophthalmic dorzolomide uses
Ophthalmic dorzolamide is used for glaucoma, as inhibition of CA in the eye reduces aqueous humor secretion and intraocular pressure
ADR of CAI
ADRs include: metabolic acidosis,
drowsiness,
hypokalemia
Acetazolomide is used to combat
Respiratory alkalosis durng mountain climbing
ROA od CAI
Acetazolomide-oral
DOrzolomide-ophthalmic solution
Drug Interactions of CAI
By alkalinizing the urine, these drugs can decrease the excretion of weak bases (amphetamines, catecholamines, etc.)
In alkaline urine,weak bases are not ionized and will not readily dissolve in water and as a result they are not excreted through urine as they cannot pass through the membrane.
