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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