Pharm study guide

Unit 5 Notes
Chapter 41 Diuretics
Drugs that increase urinary output
Two major applications
Treatment of hypertension
Mobilization of edematous fluid to prevent renal failure
Introduction to Diuretics Figure 41-1
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 41-2
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
Furosemide (Lasix) – most frequently prescribed loop diuretic
Mechanism of action
Acts on ascending loop of Henle to block reabsorption
Pharmacokinetics
Rapid onset (oral 60 min; IV 5 min)
Therapeutic uses
Pulmonary edema
Edematous states
Hypertension
Adverse effects
Hypokalemia
Hyponatremia, hypochloremia, and dehydration
Hyperglycemia & Hyperuricemia
Hypotension
Loss of volume
Relaxation of venous smooth muscle
Ototoxicity
Drug interactions
Digoxin
May cause imbalance in digoxin levels due to fluctuation in potassium levels
Ototoxic drugs May cause tinnitus
Potassium-sparing diuretics May help to prevent hypokalmia
Lithium
By lowering sodium levels can cause lithium accumulation and raise it to a toxic level
Antihypertensive agents May reduce blood pressure to critical level
Nonsteroidal anti-inflammatory drugs NSAIDs can blunt the diuretic effect of Lasix
Potassium wasting May increase hypokalemia
Preparations, dosage, and administration
Oral
Parenteral
Thiazides and Related Diuretics
Hydrochlorothiazide
Also known as benzothiadiazides
Effects similar to those of loop diuretics
Increase renal excretion of sodium, chloride, potassium,