Diuretics narrationas

Views:
 
Category: Education
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

Diuretics : 

Diuretics

Objectives : 

Objectives State the common mechanism(s) by which all diuretics increase urine production. Classify the following as potassium-sparing or potassium-wasting: thiazides, loop diuretics, spironolactone, and triamterene; state why knowing the effects of diuretics on renal potassium excretion is clinically important.   State factors that should be considered when selecting a diuretic for use. Consider efficacy of the various agents, dose-response relationships, and the potential for adverse effects in patients with other disorders. For which pathologies are the various diuretics (see B) suitable?   Describe the adverse effects and contraindications of (or precautions for) the diuretics (or diuretic classes) listed in B.

Objectives : 

Objectives State expected effects of thiazides and loop diuretics on blood levels of glucose, lipids (e.g., various cholesterol fractions and triglycerides), uric acid, calcium, and magnesium, and identify the preexisting conditions that might require extra caution if using these diuretics is anticipated. After reading this chapter and Chapter 47 on digoxin, state how changes of serum potassium levels affect the effects of the digoxin and the likely impact of hypokalemia or hyperkalemia on therapy with the cardiac glycoside. State whether combinations of named diuretics are rational, and give a reason why. For example, is it reasonable and rational to administer two thiazides, or two loop diuretics, to the same patient?   Compare and contrast the mechanisms of action, clinical uses, and typical adverse effects of mannitol with those of a thiazide or loop diuretic

Diuretics : 

Diuretics Review of renal anatomy and physiology Introduction to diuretics High-ceiling (loop) diuretics Thiazides and related diuretics Potassium-sparing diuretics Osmotic diuretics

Diuretics (cont’d) : 

Diuretics (cont’d) Drugs that increase urinary output Two major applications Treatment of hypertension Mobilization of edematous fluid, which prevents renal failure

Anatomy and Physiology : 

Anatomy and Physiology Anatomy Basic functional unit of the kidney, nephron Four functionally distinct regions Glomerulus Proximal convoluted tubule The loop of Henle Distal convoluted tubule

Anatomy and Physiology (cont’d) : 

Anatomy and Physiology (cont’d) Physiology Three basic functions Cleansing of extracellular fluid (ECF) and maintenance of ECF volume and composition Maintenance of acid-base balance Excretion of metabolic wastes and foreign substances

Anatomy and Physiology (cont’d) : 

Anatomy and Physiology (cont’d) Physiology (cont’d) Three basic renal processes Filtration—occurs at the glomerulus Reabsorption 99% of water, electrolytes, and nutrients undergo reabsorption Active tubular secretion Proximal convoluted tubule

Anatomy and Physiology (cont’d) : 

Anatomy and Physiology (cont’d) Physiology (cont’d) Processes of reabsorption that occur at specific sites along the nephron Proximal convoluted tubule Loop of Henle Distal convoluted tubule (early segment) Late distal convoluted tubule and collecting duct (distal nephron) Sodium-potassium exchange Regulation of urine concentration

Figure 40-1 Schematic representation of a nephron and collecting duct. : 

Figure 40-1 Schematic representation of a nephron and collecting duct.

Introduction to Diuretics : 

Introduction to Diuretics How diuretics work—mechanism of action Blockade of sodium and chloride reabsorption Site of action Proximal tubule produces greatest diuresis Adverse effects Hypovolemia Acid-base imbalance Electrolyte imbalances

Figure 40-2 Schematic diagram of a nephron showing sites of sodium absorption and diuretic action. : 

Figure 40-2 Schematic diagram of a nephron showing sites of sodium absorption and diuretic action.

Introduction to Diuretics (cont’d) : 

Introduction to Diuretics (cont’d) Classification of Diuretics Four major categories High ceiling (loop)—(furosemide) Thiazide—(hydrochlorothiazide) Osmotic—(mannitol) Potassium-sparing: two subdivisions Aldosterone antagonists (spironolactone) Nonaldosterone antagonists (triamterene) Fifth Group Carbonic anhydrase inhibitors

High-Ceiling (Loop) Diuretics : 

High-Ceiling (Loop) Diuretics Furosemide (Lasix) most frequently prescribed loop diuretic Mechanism of action Acts on the ascending loop of Henle to block reabsorption Pharmacokinetics Rapid onset Therapeutic Uses Pulmonary edema Edematous states Hypertension

High-Ceiling (Loop) Diuretics (cont’d) : 

High-Ceiling (Loop) Diuretics (cont’d) Adverse effects Hyponatremia, hypochloremia, and dehydration Hypotension Loss of volume Relaxation of venous smooth muscle Hypokalemia

High-Ceiling (Loop) Diuretics (cont’d) : 

High-Ceiling (Loop) Diuretics (cont’d) Adverse effects (cont’d) Ototoxicity Hyperglycemia Hyperuricemia Use in pregnancy Impact on lipids, calcium, and magnesium

High-Ceiling (Loop) Diuretics (cont’d) : 

High-Ceiling (Loop) Diuretics (cont’d) Drug interactions Digoxin Ototoxic drugs Potassium-sparing diuretics Lithium Antihypertensive agents Nonsteroidal anti-inflammatory drugs Preparations, dosage, and administration Oral Parenteral

Thiazides and Related Diuretics : 

Thiazides and Related Diuretics Hydrochlorothiazide (HydroDIURIL) Most widely used Action—distal convoluted tubule Peaks 4-6 hours Therapeutic use Essential hypertension Edema Diabetes insipidus

Thiazides and Related Diuretics (cont’d) : 

Thiazides and Related Diuretics (cont’d) Hydrochlorothiazide (HydroDIURIL) (cont’d) Adverse effects Hyponatremia, hypochloremia, and dehydration Hypokalemia Use in pregnancy and lactation Enters breast milk Hyperglycemia Hyperuricemia Impact on lipids, calcium, and magnesium

Potassium-Sparing Diuretics : 

Potassium-Sparing Diuretics Spironolactone Triamterene Amiloride

Spironolactone [Aldactone] : 

Spironolactone [Aldactone] Mechanism of action Blocks aldosterone in the distal nephron Retention of potassium Increased excretion of sodium Therapeutic uses Hypertension Edematous states Severe heart failure Primary hyperaldosteronism

Spironolactone [Aldactone] (cont’d) : 

Spironolactone [Aldactone] (cont’d) Adverse effects Hyperkalemia Benign and malignant tumors Endocrine effects Drug interactions Thiazide and loop diuretics Agents that raise potassium levels

Triamterene [Dyrenium] : 

Triamterene [Dyrenium] Mechanism of action Disrupts sodium-potassium exchange in the distal nephron A direct inhibitor of the exchange mechanism Decreases sodium reuptake Inhibits ion transport Therapeutic uses Hypertension Edema

Triamterene [Dyrenium] (cont’d) : 

Triamterene [Dyrenium] (cont’d) Adverse effects Hyperkalemia Leg cramps Nausea Vomiting (rarely) Dizziness Blood dyscrasias

Osmotic Diuretic : 

Osmotic Diuretic Mannitol [Osmitrol] Diuresis in lumen of the nephron Pharmacokinetics Drug must be given parenterally Therapeutic uses Prophylaxis of renal failure Reduction of intracranial pressure Reduction of intraocular pressure

Osmotic Diuretic (cont’d) : 

Osmotic Diuretic (cont’d) Mannitol [Osmitrol] (cont’d) Adverse effects Edema Headache Nausea Vomiting Fluid and electrolyte imbalance

Osmotic Diuretic (cont’d) : 

Osmotic Diuretic (cont’d) Urea, glycerin, and isosorbide Mechanism of action Filtered at the glomerulus Undergo limited reabsorption Promote osmotic diuresis Therapeutic uses Reduction of intraocular pressure Reduction of intracranial pressure Preparation, dosage, and administration Urea [Ureaphil] intravenously Glycerin [Osmoglyn] and isosorbide [Ismotic] by mouth

authorStream Live Help