drugs that increase the output of urine

tx of HTN, mobilization of edematous fluid (reduce edema in body), prevent renal failure (push kidney to produce urine production)

work in nephron 

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1. glomerulus, 2. proximal convoluted tubule, 3. loop of henle, 4. distal convoluted tubule

cleansing of extracellular fluid (ECF)

maintenance of blood volume & composition

maintenance of acid-base balance

excretion of metabolic wastes & foreign substances

filtration (glomerulus) - first step in urine formation; small molecules are filtered, expecially Na & Cl ions

reabsorption - electrolytes, glucose - by active transport; H2O follows by passive transport

blockade of Na & Cl reabsorption

preventing passive reabsorption of H2O

↑ in urine flow

block greatest amt of reabsorption & produce the greatest diuresis

diuretics can cause hypovolemia, acid-base imbalance & distrubance of electrolyte levels

high ceiling (loop) diuretics (most commonly used)

thiazide diuretics

potassium-sparing diuretics

osmotic (usually reserved for emergencies, strongest)

furosemide (Lasix)

"high-ceiling (loop) diuretics"

block reabsorption of Na & Cl ions, block passive reabsorption of H2O

Route: IV works much faster than PO

Use: pulmonary edema; edema of hepatic, cardiac or renal origin; HTN incontrolled by other diuretics; severe renal impairment

Effects: rapid, massive mobilization of fluid, excreted as urine

AE: hyponatremia, hypochloremia; dehydration; hypotension r/t hypovolemia & venous dilation; hypokalemia; ototoxicity; hyperglycemia; avoid in pregnancy

DD: digoxin; lithium increases levels; ototoxic drugs; antihypertensive drugs; NSAIDs

hydrochlorothiazide (HCTZ)

"thiazide diuretics"

↑ secretion of Na, Cl, K & H2O; elevate plasma glucose & uric acid

Route: PO only

Use: essential HTN; edema (mild to moderate HF, renal or hepatic); diabetes insipidus

Effects: ↑ urine flow

AE: similar to high-ceiling; no ototoxicity

DD: similar to high-ceiling (digoxin; lithium, etc.)

spironolactone (Aldactone)

"potassium-sparing diuretics"

blocks action of aldosterone, ↑ excretion of Na & retention of K

Route: PO

Use: HTN; edema; severe HF (generally used w/ high-ceiling or thiazide diuretics)

Effects: scanty diuresis (low level - small amt)

AE: hyperkalemia

DD: must never be takin w/ K supplements or other K sparing diuretics, ACE inhibitors, ARBs or direct renin inhibitors

triamterene (Dyrenium)

"potassium-sparing diuretics"

blocks action of aldosterone, increasing excretion of Na & retention of K

Use: HTN; edema; used w/ other diuretics to conserve K

Effects: mild diuresis

AE: hyperkalemia; N, V; leg cramps; dizziness

HCTZ/triamterene (Dyazide)

"combination drugs"

Use: essential HTN; edema; diabetes insipidus

Effects: increased urine flow

AE: similar to high-ceiling; no ototoxicity

DD: similar to high-ceiling (digoxin, lithium, etc.)

mannitol (Osmitrol)

"osmotic diuretics"

creates an osmotic forces w/in the nephron

Route: IV only (not absorbed by GI tract)

Use: prophylaxis of renal failure; reduction of ICP (intracranial pressure) & IOP (intraocular pressure)

Effects: isn't reabsorbed, remains in nephron, drawing H2O w/ it; in the brain & eye, osmotic force reduces edema (stays in blood stream)

AE: systemic edema (except in brain); can precipitate CHF & pulmonary edema

serum K falls below 3.5 mEq/L

caused by diuretics; insufficient K intake; alkalosis & excessive insulin; ↑ renal excretion of K; prolonged/excessive V or D (ex: food poisoning), laxative abuse; diaphoresis (excessive sweating)

Effects: weakness, paralysis of skeletal muscle; abnormalities in cardiac impulse conduction

Tx: KCl (most common treatment), KPO4, KCO3 (PO, take w/ meals & H2O)

AE: (of KCl) GI irritant - N, V, D, abd pain; high level concentrations result in GI bleed

If given IV, diluted and given slowly, , NEVER IV push

serum K rises above 5 mEq/L

caused by severe tissue trauma; untreated Addison's disease; acute acidosis;misuse of K-sparing diuretics; overdose of IV K

Effects: mild elevation (5-7mEq/L) = T wave heightening & prolonged PR interval.

high elevation (8-9 mEq/L) = V tach, V fib, cardiac arrest; confusion, anxiety, numbness/tingling in lips, hands feet, weakness/heaviness in legs

Tx: withhold K containing foods & drugs; infusion of Ca salt; IV infusion of glucose & insulin; if acidosis is present, infuse sodium bicarbonate

additional Tx: sodium polystyrene solution (Kayexalate) PO or PR; dialysis

muscle weakness, leg cramps; N, V, paralytic ileus; paresthesias; ventricular dysrhythmias; bradycardia; enhanced digoxin effects

irritability; anxiety; abdominal cramps; D; weakness; paresthesias; irregular pulse; V fib; cardiac arrest

< 0.5 mEq/L

caused by D; hemodialysis; renal disease; chronic alcoholism; diabetes; pancreatitis

Tx: replacement: magnesium gluconate PO; magnesium hydroxide PO tablet or MOM; magnesium sulfate IM/IV

AE: cardiac & skeletal muscle - excitability to tetany; CNS excitability - disorientation, psychosis, sz; renal injury - due to calcium stones in nephrons

> 3 mEq/L

caused by renal insufficiency, especially when Mg containing antacids or cathartics are used

AE: neuromuscular blockade = muscle weakness, respiratory muscle paralysis; EKG changes

DD: can intensify effects of neuromuscular blocking agents

Tx: IV calcium

confusion, hyperactive deep tendon reflexes; tremors; sz; cardiac dysrhythmias

lethargy, drowsy; N, V; loss of deep tendon reflexes; somnolence; respiratory arrest; cardiac arrest