Thiazide diuretics Flashcards
Thiazide diuretic site of action
must enter tubular fluid…
Early DCT
MOA
block electroneutral NaCl transporter in aldosterone-independent segment of DT
Results
(DCT responsible for about 5% of NaCl reabsorption)…Moderate potency
moderate loss of Na, K, and Cl…causes 3X increase in urine flow
Sodium loss results in reduced GFR (chronic)
elevation of excreted urinary potassium (hypokalemia)
increase excretion of titratable acid due to inc delivery of Na to distal tubule
decrease the urinary excretion of Ca
increase urinary excretion of Mg
increased Na, K, Cl, and H20 excretion
Thiazides general
Used chronically
Cheap
Clinical uses
Diuretic to reduce edema associated w/:
- -CHF
- -Cirrhosis
- -Nephrotic syndrome
Hypercalciurea and renal calcium stones
reduce BP in essential HTN (alone)
augment action of other antihypertensives
osteoporosis
Nephrogenic Diabetes insipidus
With possible exceptions of metolazone and indapamide, most thiazides are ineffective when GFR <30-40.
Why?
like loop diuretics, thiazides require secretion into tubular fluid to exert effect
Class I
Preferably used when GFR >50
- -Hydrochlorothiazide
- -Chlorthalidone
- -Quinethazone
Class II
More potent, might be effective in some pts w/ GFR 30
- -Metolazone….10x more potent than HCTZ
- -Indapamide…..20x more potent than HCTZ
Side effects
Depletion phenomena
Retention phenomena
Metabolic changes
Hypersensitivity and other
Depletion phenomena
Hypokalemia
Hypochloremic alkalosis
Dilutional hyponatremia
hypomagnesemia
Retention phenomena
Hyperuricemia
hypercalcemia
hyperglycemia
hyperlipidemia
Metabolic changes
hyperglycemia
hyperlipidemia
hypersecretion of renin and aldosterone
hypersensitivity and other
fever, rash, purpurea
sialadentitis
pancreatitis
withdrawal edema
widely used to treat mild or moderate…
HTN
most popular drug for therapy of…
High BP
