K+ SPARING DIURETICS // type 1Where: late distal tubule, collecting ductHow: block sodium channel directlyWhat: highly basic, cationic formWho: amiloride, triamterene
K+ SPARING DIURETICS // type 2How: blocks aldosterone receptor by gene expressionWhat: synthetic steroidWho: spironolactone
OTHER AGENTSHow: ↑ renal blood flow and GFRWhat: methylxanthinesWho: theophylline, caffeine, theobromine
DiureticsDiureticsDiuretics
Complications of diuretics
VOLUME DEPLETION•Loop diuretics, thiazides•Sx: cramps, weak, dizzy, orthostatic hypotension, and ↓urine output•↓Renal perfusion•↑BUN•↓Mental & cardio function
HYPOKALEMIA•Loop diuretics < thiazides•Chlorthalidone: largest extent•Dose-related•↑Risk of ventricular arrhythmias•Low dose thiazides should be used for hypertension tx•Fix with oral KCl, K+ sparing diuretics, K+ rich food, or slow release KCl preps
HYPERURICEMIA•Thiazides, loop diuretics•Dose-related•Volume contraction ↑uratereabsorption•Diuretics compete with uric acid for OAT•Gout not a contraindication
HYPERLIPIDEMIA•Thiazides, chlorthalidone, furosemide•Dose-related•↑Hepatic lipoprotein synthesis and/or altered lipoprotein catabolism may be the cause
HYPOMAGNESEMIA•Cardiac arrhythmias, sudden death, atherogenicproblems•An infrequent problem
HYPERCALCEMIA•Long term thiazide use•Good for patients with kidney stones•Tx with loop diuretics
HYPONATREMIA•Enhanced ADH secretion•Large doses of diuretic, too much water, too little sodium in diet will worsen it
ALKALOSIS•Concurrent with potassium depletion•Contraction of ECF volume ↑aldosterone which causes retention of H+ in urine
ACIDOSIS•Acetazolamide (CAI): inhibitory effect on CA excretion of HCO3-•K+ sparing diuretics: ↓K+ and H+ secretion
HYPERGLYCEMIA•↓Insulin secretion•↑Insulin resistance•Thiazide and loop diuretics worsen glucose tolerance, cause diabetes onset•Associated with hypokalemia•Diabetes not a contraindication
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