Edema thiazide

Amiloride (Midamor) is used in the treatment of CHF and hypertension and is often used with a thiazide diuretic. Spironolactone and triamterene are also used in tiie treatment of hypertension and edema caused by CHF, cirrhosis, and the nephrotic syndrome Amiloride, spironolactone, and triamterene are also available with hydrochlorothiazide, a thiazide diuretic that enhances tiie antihypertensive and diuretic effects of the drug combination while still conserving potassium. 

Thiazides and related diuretics are used in the treatment of hypertension, edema caused by CHF, hepatic cirrhosis, corticosteroid and estrogen therapy, and renal dysfunction. 

Two types of diuretics are used for volume management in HF thiazides and loop diuretics. Thiazide diuretics such as hydrochlorothiazide, chlorthalidone, and metolazone block sodium and chloride reabsorption in the distal convoluted tubule. Thiazides are weaker than loop diuretics in terms of effecting an increase in urine output and therefore are not utilized frequently as monotherapy in HF. They are optimally suited for patients with hypertension who have mild congestion. Additionally, the action of thiazides is limited in patients with renal insufficiency (creatinine clearance less than 30 mL/minute) due to reduced secretion into their site of action. An exception is metolazone, which retains its potent action in patients with renal dysfunction. Metolazone is often used in combination with loop diuretics when patients exhibit diuretic resistance, defined as edema unresponsive to loop diuretics alone. 

Thiazide diuretics such as chlorothiazide act on the distal tubule, a portion of the tubule that is permeable to sodium. The mechanism of action of these diuretics involves inhibition of NaCl reabsorption by blocking the Na+, CL symporter in the luminal membrane. The thiazide diuretics are only moderately effective due to the location of their site of action. Approximately 90% of the filtered Na+ ions have already been reabsorbed when the filtrate reaches the distal tubule. These drugs may be used for treatment of edema associated with heart, liver, and renal disease. Thiazide diuretics are also widely used for the treatment of hypertension. 

Potassium-sparing diuretics are often coadministered with thiazide or loop diuretics in the treatment of edema and hypertension. In this way, edema fluid is lost to the urine while K+ ion balance is better maintained. The aldosterone antagonists are particularly useful in the treatment of primary hyperaldosteronism. 

Diuretics are the primary pharmacologic therapy for edema. Loop diuretics are the most potent, followed by thiazide diuretics and then potassiumsparing diuretics. 

Mobilization of edemas (A) In edema there is swelling of tissues due to accumulation of fluid, chiefly in the extracellular (interstitial) space. When a diuretic is given, increased renal excretion of Na and H2O causes a reduction in plasma volume with hemoconcentra-tion. As a result, plasma protein concentration rises along with oncotic pressure. As the latter operates to attract water, fluid will shift from interstitium into the capillary bed. The fluid content of tissues thus falls and the edemas recede. The decrease in plasma volume and interstitial volume means a diminution of the extracellular fluid volume (EFV). Depending on the condition, use is made of thiazides, loop diuretics, aldosterone antagonists, and osmotic diuretics. 

Therapy of congestive heart failure. By lowering peripheral resistance, diuretics aid the heart in ejecting blood (reduction in afterload, pp. 132, 306) cardiac output and exercise tolerance are increased. Due to the increased excretion of fluid, EEV and venous return decrease (reduction in preload, p. 306). Symptoms of venous congestion, such as ankle edema and hepatic enlargement, subside. The drugs principally used are thiazides (possibly combined with K+-sparing diuretics) and loop diuretics. 

Thiazide diuretics (benzothiadia-zines) include hydrochlorothiazide, benzthiazide, trichlormethiazide, and cyclothiazide. A long-acting analogue is chlorthalidone. These drugs affect the intermediate segment of the distal tubules, where they inhibit a Na+/Ch cotransport, Thus, reabsorption of NaQ and water is inhibited. Renal excretion of Ca decreases, that of Mg + increases. Indications are hypertension, cardiac failure, and mobilization of edema. 

The abihty of metolazone, chlorothalidone, and indapamide to remove edematous liquid from the body is practically identical to that of thiazide diuretics. These drugs are used for relieving edema associated with hepatic, renal, and cardiac diseases, as well as for treating general hypertension either independently, or in combination with other drugs. 

Indapamide is a derivative of benzolsulfonamide and its mechanism of action is analogous to that of thiazides. It is intended for lowering arterial blood pressure and as an adjuvant drug for treating edema caused by cardiac insufficiency. Synonyms of this drug are lozol and others. 

Hydrochlorothiazide A Spironolactone Aldactazide) [Antihypertensive/Thiazide K Sparing Diuretic] Uses Edema, HTN Action Thiazide K -sparing diuretic Dose 25-200 mg each component/d, doses Caution [D, +] Contra Sulfonamide aUa-gy Disp Tabs (HCTZ/spironolactone) 25 mg/25 mg, 50 mg/50 mg SE Photosens, X BP, t or -1-K% -1- Na% hypoglycemia, hyperlipidemia, hyperuricemia Additional Interactions t Risk of hypokalemia W/ ACEIs, K-sparing diuretics, K supls, salt substitutes -1- effects OF digoxin EMS See Hydrochlorothiazide Amiloride OD See Hydrochlorothiazide Amiloride... 

Uses Edema, HTN, CHF, h atic cirrhosis Action Loop diuretic -1- reabsorption of Na Cr in ascending loop of Henle distal tubule Dose 5-20 mg/d PO or IV 200 mg/d max Caution [B, ] Contra Sulfonylurea sensitivity Disp Tabs, inj SE Orthostatic -1- BP, HA, dizziness, photosens, electrolyte imbalance, blurred vision, renal impair Notes 20 mg torsemide = 40 mg furosemide Interactions t Risk of ototox W/ aminoglycosides, cisplatin t effects W/ thiazides t effects OF anticoagulants, antih5rpCTtensives, Li, salicylates X effects IT/barbiturates, carbamaz ine, cholestyramine, NSAIDs, phenytoin, phenobarbital, probenecid, dandehon EMS t Effects of anticoagulants monitor for S/Sxs tinnitus, monitor ECG for hypokalemia (flattened T waves) OD May cause HA, hypotension, hypovolemia, and hypokalemia give IV fluids symptomatic and supportive... 

Sodium restriction is essential to control the edema. Diuretics like thiazides or loop diuretics are indicated in patients who are symptomatic from the edema. 

Triamterene can be used in the treatment of congestive heart failure, cirrhosis, and the edema caused by secondary hyperaldosteronism. It is frequently used in combination with other diuretics except spironolactone. Amiloride, but not triamterene, possesses antihypertensive effects that can add to those of the thiazides. 

Nephrotic syndrome is characterized by proteinuria and edema due to some form of glomerulonephritis. The resulting fall in plasma protein concentration decreases vascular volume, which leads to diminished renal blood flow. This in turn causes secondary aldosteronism characterized by Na and water retention and K+ depletion. Rigid control of dietary Na is essential. Therapy of the nephrotic syndrome using a thiazide (possibly with a K -sparing diuretic) to control the secondary aldosteronism, is a useful initial approach to treatment Since nephrotic edema is frequently more difficult to control than cardiac edema, it may be necessary to switch to a loop diuretic (and spironolactone) to obtain adequate diuresis. 

Table 1.13. Most diuretics are designed to deal with conditions of edema by reducing the reabsorption of chlorides, sodium, and water as these are the major constituents of edema fluid. Diuretics are grouped into five main categories loop diuretics, thiazides, potassium-sparing diuretics, osmotic diuretics, and carbonic...

In which of the following are thiazide diuretics ineffective Edema caused by CHF... 

Lithium Mechanism of action uncertain suppresses inositol signaling and inhibits glycogen synthase kinase-3 (GSK-3), a multifunctional protein kinase No significant antagonistic actions on autonomic nervous system receptors or specific CNS receptors no sedative effects Bipolar affective disorder-prophylactic use can prevent mood swings between mania and depression Oral absorption, renal elimination half-life 20 h. narrow therapeutic window (monitor blood levels) Toxicity Tremor, edema, hypothyroidism, renal dysfunction, dysrhythmias pregnancy category D Interactions Clearance decreased by thiazides and some NSAIDs... 

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