Thiazide Diuretics Flashcards
What is the mechanism of action of thiazide diuretics?
Inhibition of Na/Cl symporter is the distal convoluted tubule
Increase in reabsorption of Ca due to stimulation of Na/Ca counter transporter
What drugs are thiazide diuretics?
Chlorothiazide, Hydrochorothiazide, Trichlormethiazide, Chlorthalidone
What are thiazide diuretics referred to as?
rescue diuretics
In what routes are thiazide diuretics absorbed well in?
all routes
How quickly, and how long, do responses occur when thiazide diuretics are used?
the response occurs 2-3 hours and lasts 6-12 hours
What are thiazide diuretics used for?
antihypertensive agent, used as an adjunct, treatment of post parturient udder edema in cattle, Ca-oxalate uroliths, and nephrogenic diabetes insipidus in dogs
What are the adverse effects and contraindications of thiazides?
Adverse effects - fluid and electrolyte imbalance, hypokalemia and hyperuricemia
Contraindications - hyperglycemia and glucosuria if used in diabetic and prediabetic animals
What electrolyte imbalance is associated with prologed thiazide use?
hypercalcemia
How do thiazidees produce hyperglycemia and glucosuria in diabetic and prediabetic animals?
they inhibit the conversion of proinsulin to insulin
What are the types of potassium-sparing diuretics?
Na channel blockers and aldosterone antagonists
What drugs are the Na channel blockers?
triamterene and amiloride
What drugs are the aldosterone antagonists?
spironolactone and potassium canrenoate
How do Na channel blockers work?
They block Na channels and reduce the luminal potential and the driving force for K secretion. They also reduce the lumen negative potential which decreases H secretion in the intercalated cells
What is the net effect of Na channel blockers?
Increased Na, decreased K, decreased H
What is the mechanism of action of aldosterone antagonists?
they completely inhibit the binding of aldosterone to its receptors and thereby reduce the synthesis of Aldosterone-induced proteins (AIP). Therefore, the antagonists inhibit some functions of AIP
What AIP functions do aldosterone antagonists inhibit?
Synthesis of Na/K channels
Synthesis of Na/K ATPase
Mitochondrial ATP production
What is the net effect of aldosterone antagonists?
increased Na, decreased K, and decreased H
K sparing diuretics are used in combination with ____ ____ diuretics.
potassium losing
In what cases are potassium sparing diuretics used in combination with potassium losing diuretics?
Chronic use for treatment of CHF
Treatment of aldosteronism
Treatment of ascites
What type of drugs are carbonic anhydrase inhibitors?
sulfonamide derivitives
What do carbonic anhydrase inhibitors do?
they inhibit carbonic anhydrase enzyme and reduce the number of hydrogen ions available for Na/H exchange
What does carbonic anhydrase inhibitors result in?
Increase NaHCO3 (Na bicarbonate ) excretion Increased K excretion Increased Cl retention (causes hypercholermic acidosis)
What therapeutic uses are carbonic anhydrase inhibitors used for?
for glaucoma and metabolic alkalosis
How are carbonic anhydrase inhibitors effective in treating glaucoma?
inhibition of ciliary body carbonic anhydrase which causes decreases aqueous humor production
