Lecture 16 - Diuretics

‭Fluid Overload/Hypervolemia‬ ‭Idiopathic‬ ‭‬ C ● ‭ ongestive heart failure‬ ‭●‬ ‭Kidney failure‬ ‭●‬ ‭Cirrhosis of the liver‬ ‭Iatrogenic‬ ‭‬ S ● ‭ odium intake‬ ‭●‬ ‭IV fluids‬ ‭●‬ ‭Medications‬ ‭Renal Anatomy/Physiology‬ ‭Function of the Kidneys‬ ‭●‬ ‭Cleansing ECF and maintaining its volume/composition‬ ‭○‬ ‭Impacted by diuretics‬ ‭●‬ ‭Maintenance of acid-base balance (homeostasis)‬ ‭●‬ ‭Excretion of metabolic wastes and foreign substances‬ ‭3 Basic Renal Processes‬ ‭Filtration‬ ‭‬ ● ‭●‬ ‭●‬ ‭●‬ ‭ ccurs at the glomerulus‬ O ‭Nonselective except large molecules (albumin)‬ ‭Mostly sodium and chloride‬ ‭125 mL/min‬ ‭Reabsorption‬ ‭‬ W ● ‭ here diuretics have an effect‬ ‭●‬ ‭99% of water, electrolytes, and‬ ‭nutrients undergo reabsorption‬ ‭●‬ ‭Active and passive transport‬ ‭Nephron Sites of Reabsorption‬ ‭●‬ ‭Proximal convoluted tubule‬ ‭●‬ ‭Loop of Henle‬ ‭○‬ ‭Permeable to water‬ ‭○‬ ‭Hypertonic outside‬ ‭●‬ ‭Distal convoluted tubule (early‬ ‭segment)‬ ‭●‬ ‭Late distal convoluted tubule and collecting duct (distal nephron)‬ ‭○‬ ‭Sodium-potassium exchange‬ ‭○‬ ‭Regulation of urine concentration‬ ‭Active Tubular Secretion‬ ‭‬ A ● ‭ t proximal convoluted tubule‬ ‭●‬ ‭Two pumps from plasma into nephron‬ ‭○‬ ‭One for acids and one for bases‬ ‭Diuretics‬ ‭General Characteristics‬ ‭MOA‬ ‭●‬ ‭Block sodium and chloride reabsorption‬ ‭○‬ ‭Percentage reabsorbed is directly proportional to diuresis‬ ‭●‬ ‭Water passively follows the solutes‬ ‭Therapeutic Use‬ ‭‬ D ● ‭ iuresis:‬‭Reduction of (extra) fluid volume‬ ‭●‬ ‭Ex. HTN, HF, glaucoma, edema, acute kidney failure‬ ‭○‬ ‭Caused by excessive fluid‬ ‭Site of Action‬ ‭●‬ ‭Proximal or distal tubule‬ ‭Adverse Effects‬ ‭‬ H ● ‭ ypovolemia (excessive fluid loss)‬ ‭●‬ ‭Acid-base imbalance‬ ‭●‬ ‭Electrolyte imbalances‬ ‭4 Categories of Diuretics‬ ‭‬ ● ‭●‬ ‭●‬ ‭●‬ ‭ oop diuretics‬ L ‭Thiazides‬ ‭Osmotic agents‬ ‭Potassium-sparing diuretics‬ ‭○‬ ‭Aldosterone antagonists (spironolactone)‬ ‭○‬ ‭Non-aldosterone antagonists (triamterene)‬ ‭Loop Diuretics‬ ‭Prototype‬ ‭●‬ ‭Furosemide (Lasix)‬ ‭MOA‬ ‭●‬ ‭Acts primarily on the thick segment of the‬‭ascending‬‭limb‬‭of the LOH‬ ‭○‬ ‭At which 20% of sodium and chloride is normally reabsorbed‬ ‭●‬ ‭Blocks reabsorption of sodium and chloride‬ ‭●‬ ‭Still effective with poor renal blood flow and low GFR‬ ‭○‬ ‭Works in patients with‬‭renal impairment‬ ‭Pharmacokinetics‬ ‭‬ R ● ‭ apid onset‬ ‭●‬ ‭PO:‬‭60 minutes, can last up to 8 hrs‬ ‭○‬ ‭In less immediate cases‬ ‭●‬ ‭IV/IM:‬‭5 minutes‬ ‭○‬ ‭In critical situations‬ ‭Therapeutic Uses/Effects‬ ‭‬ ● ‭●‬ ‭●‬ ‭●‬ ‭ apid diuresis‬ R ‭Pulmonary edema‬ ‭Edematous states‬ ‭Hypertension (if alternative drugs are ineffective)‬ ‭Adverse Effects‬ ‭●‬ ‭Dehydration‬ ‭○‬ ‭Dry mucous membranes‬ ‭○‬ ‭Skin tenting‬ ‭○‬ ‭Headaches, dizziness‬ ‭●‬ ‭Hypotension‬ ‭●‬ ‭Hypokalemia‬ ‭○‬ ‭Lost in secretion of distal nephron‬ ‭○‬ ‭Causes dysrhythmias‬ ‭●‬ ‭Hyponatremia‬ ‭●‬ ‭Hypochloremia‬ ‭●‬ ‭Ototoxicity (transient, rare)‬ ‭Hypokalemia‬ ‭●‬ ‭Alkalosis‬ ‭‬ ● ‭●‬ ‭●‬ ‭●‬ ‭●‬ ‭ hallow respirations‬ S ‭Irritability‬ ‭Confusion, drowsiness‬ ‭Weakness, fatigue‬ ‭Arrhythmias‬ ‭○‬ ‭Tachycardia‬ ‭○‬ ‭Irregular rhythm‬ ‭○‬ ‭Bradycardia‬ ‭ ‬ ‭Lethargy‬ ● ‭●‬ ‭Thready pulse‬ ‭●‬ ‭Intestinal motility‬ ‭○‬ ‭N/V‬ ‭○‬ ‭Ileus‬ ‭Potassium-Rich Foods‬ ‭●‬ ‭Avocadoes‬ ‭●‬ ‭Winter squash‬ ‭●‬ ‭Green, leafy vegetables‬ ‭●‬ ‭Tomatoes‬ ‭●‬ ‭Potatoes‬ ‭●‬ ‭Wild-caught salmon‬ ‭●‬ ‭Dried fruits‬ ‭●‬ ‭Pomegranate‬ ‭Drug Interactions‬ ‭‬ D ● ‭ igoxin‬ ‭●‬ ‭Ototoxic drugs‬ ‭○‬ ‭Ex. aminoglycosides‬ ‭●‬ ‭Potassium sparing diuretics‬ ‭Thiazides‬ ‭Prototype‬ ‭‬ H ● ‭ ydrochlorothiazide (Hydrodiuril)‬ ‭●‬ ‭Most widely used diuretic/antihypertensive‬ ‭Site of Action‬ ‭●‬ ‭Early segment of the distal convoluted tubule‬ ‭MOA‬ ‭‬ ● ‭●‬ ‭●‬ ‭●‬ I‭ ncreases excretion of sodium, chloride, potassium, and water‬ ‭Elevates levels of uric acid and glucose‬ ‭Ineffective with low GFR (15-20 mL/min)‬ ‭Affects the distal convoluted tubule‬ ‭○‬ ‭At which 10% of reabsorption normally occurs‬ ‭○‬ ‭Less diuresis than loop diuretics‬ ‭Pharmacodynamics‬ ‭‬ O ● ‭ ral only‬ ‭●‬ ‭Peaks in 4-6 hours‬ ‭●‬ ‭Can persist for 12 hours‬ ‭Therapeutic Uses‬ ‭‬ C ● ‭ auses‬‭diuresis‬ ‭●‬ ‭Essential HTN‬ ‭●‬ ‭Edema‬ ‭Adverse Effects‬ ‭‬ ● ‭●‬ ‭●‬ ‭●‬ ‭ ften identical to loop diuretics except ototoxicity‬ O ‭GI upset (common)‬ ‭Dehydration‬ ‭Electrolyte imbalance‬ ‭○‬ ‭Hypokalemia‬ ‭○‬ ‭Hyponatremia‬ ‭○‬ ‭Hypochloremia‬ ‭Drug Interactions‬ ‭●‬ ‭Digoxin:‬‭Increased risk for toxicity related to hypokalemia‬ ‭○‬ ‭Life-threatening dysrhythmias‬ ‭●‬ ‭Augments hypertensive medications‬ ‭●‬ ‭Can be combined with ototoxic agents without increased risk of hearing loss‬ ‭Nursing Considerations for Loop Diuretics & Thiazides‬ ‭‬ B ● ‭ aseline data‬ ‭●‬ ‭Monitor I&Os‬ ‭●‬ ‭Therapeutic effects‬ ‭Minimizing Adverse Effects‬ ‭‬ H ● ‭ ypokalemia‬ ‭●‬ ‭Dehydration‬ ‭●‬ ‭Hypotension‬ ‭Promoting Adherence‬ ‭●‬ ‭Ideal time to take medication‬ ‭○‬ ‭In the morning‬ ‭○‬ ‭Frequent urination‬ ‭●‬ ‭Self-monitoring of blood pressure‬ ‭●‬ ‭Fall risk‬ ‭Potassium-Sparing Diuretics‬ ‭●‬ ‭Rarely used as monotherapy‬ ‭Prototype‬ ‭●‬ ‭Spironolactone (Aldactone)‬ ‭MOA‬ ‭●‬ ‭Blocks aldosterone in the‬‭distal nephron‬ ‭○‬ ‭At which there is normally 1-5% reabsorption‬ ‭○‬ ‭Less pronounced diuresis; not main indication‬ ‭●‬ ‭Retention of potassium‬ ‭●‬ ‭Increased excretion of sodium‬ ‭Indications‬ ‭‬ M ● ‭ odest diuresis‬ ‭●‬ ‭Substantially less potassium excretion‬ ‭Therapeutic Uses‬ ‭●‬ ‭Most often used in conjunction with other meds‬ ‭○‬ ‭Loop diuretics and thiazides‬ ‭○‬ ‭Prevent hypokalemia‬ ‭●‬ ‭Hypertension‬ ‭●‬ ‭Edema‬ ‭●‬ ‭Heart failure‬ ‭Adverse Effects‬ ‭●‬ ‭Hyperkalemia‬ ‭ ‬ ‭Dysrhythmias‬ ○ ‭ ‬ ‭Endocrine effects (steroid-derivative):‬ ● ‭○‬ ‭Gynecomastia‬ ‭○‬ ‭Irregular menses‬ ‭○‬ ‭Hirsutism‬ ‭○‬ ‭Impotence‬ ‭○‬ ‭Deepening of voice‬ ‭Hyperkalemia‬ ‭●‬ ‭Muscle weakness‬ ‭●‬ ‭Oliguria, anuria‬ ‭●‬ ‭Respiratory distress‬ ‭●‬ ‭Decreased cardiac contractility‬ ‭●‬ ‭EKG changes‬ ‭○‬ ‭Peaked T waves‬ ‭○‬ ‭QRS widening‬ ‭●‬ ‭Hyperreflexia, areflexia (flaccid)‬ ‭●‬ ‭Normal levels: 3.5-5.2 mEq/L‬ ‭●‬ ‭Monitor:‬ ‭○‬ ‭Weight, BP, HR, etc.‬ ‭Drug Interactions‬ ‭‬ T ● ‭ hiazides and loop diuretics‬ ‭●‬ ‭Agents that raise potassium levels‬ ‭○‬ ‭Potassium supplements‬ ‭○‬ ‭Potassium-rich foods‬ ‭○‬ ‭ACEs, ARBs, renin-inhibitors‬ ‭■‬ ‭Can suppress aldosterone secretion‬ ‭○‬ ‭Salt substitutes (potassium chloride)‬ ‭■‬ ‭Often used in hypertensive patients‬ ‭Contraindications/Precautions‬ ‭‬ P ● ‭ atients with hyperkalemia‬ ‭●‬ ‭Severe kidney failure/disease‬ ‭●‬ ‭Electrolyte imbalances‬ ‭Safe Handling and Administration (NIOSH)‬ ‭‬ P ● ‭ otentially hazardous drugs‬ ‭●‬ ‭Can cause adverse effects in healthcare workers handling drugs‬ ‭●‬ ‭Advised to wear a protective gown and gloves when crushing pills‬ ‭Osmotic Agents‬ ‭●‬ ‭Work at the proximal convoluted tubule‬ ‭○‬ ‭At which 65% of solutes are normally reabsorbed‬ ‭●‬ ‭Often not used due to great amount of reabsorption blocked‬