CH 35 DIURETICS Flashcards
basic functional unit of kidney
nephron
Three basic functions of kidney
Cleansing of extracellular fluid (ECF) and maintenance of ECF volume and composition
Maintenance of acid-base balance
Excretion of metabolic wastes and foreign substances
3 basic renal processes
- filtration- occurs at glomerulus
- reabsorption
- active tubular secretion
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
HOW DIURETICS WORK
BLOCKS NA AND CL REABSORPTION
Classifications of diuretics
Loop: Furosemide Thiazide: Hydrochlorothiazide Osmotic: Mannitol--- NOT PAYING ATTENTION TO FOR TEST Potassium-sparing: Two subcategories Aldosterone antagonists (spironolactone) Nonaldosterone antagonists (triamterene)
Lasix mechanism of action
acts on ascending loop of henle to block reabsorption
Lasix pharmacokinetics
rapid onset
po 60 min
IV 5 min
Lasix uses
- pulmonary edema
- edema
- HTN
Lasix AE
Hyponatremia, hypochloremia, and dehydration Hypotension Loss of volume Relaxation of venous smooth muscle Hypokalemia Ototoxicity Hyperglycemia Hyperuricemia Use in pregnancy- AVOID, Category C Impact on lipids, calcium, and magnesium
Lasix drug interactions
Digoxin- narrow TI- increases risk of arrhythmias
Ototoxic drugs
Potassium-sparing diuretics
Lithium- excretion is reduced in a low sodium environment- so you can have toxic lithium doses, narrow TI, all kinds of things can affect lithium
Antihypertensive agents
Nonsteroidal antiinflammatory drugs
loop diuretics
Ethacrynic acid [Edecrin] Bumetanide [Bumex] Torsemide [Demadex] All can cause: Ototoxicity, hypovolemia, hypotension, hypokalemia, hyperuricemia, hyperglycemia, and disruption of lipid metabolism
thiazides
Effects similar to those of loop diuretics (except not as efficiaoius- not as signficaint)
Increase renal excretion of sodium, chloride, potassium, and water
Elevate levels of uric acid and glucose
Maximum diuresis is considerably lower than with loop diuretics
Not effective when urine flow is scant (unlike with loop diuretics)
hctz
action- early segment distal convoluted tubule
peaks 4-6 hrs
uses- essential HTN, edema, DI
HCTZ AE
Hyponatremia, hypochloremia, and dehydration
Hypokalemia
Use in pregnancy and lactation- DO NOT USE
Hyperglycemia
Hyperuricemia
Impact on lipids, calcium, and magnesium
hctz drug interactions
Digoxin- increased potentional for arrhythmias
Augments effects of hypertensive medications
Can reduce renal excretion of lithium (leading to accumulation)
NSAIDs may blunt diuretic effect
Can be combined with ototoxic agents without increased risk of hearing loss
So if you need diuretic and pt is on another ototoxic drug (like atb) you can order HCTZ
potassium-sparing diuretics
modest increase in UO
substantial decrease in K excretion
rarely monotherapy
aldosterone antagonist
spironolactone
nonaldersterone antagonist
triamterene
amiloride
spironolactone mechanism of action
Blocks aldosterone in the distal nephron
Retention of potassium
Increased excretion of sodium
spironolactone therapeutic uses
Hypertension Edematous states Heart failure (decreases mortality in severe failure) Primary hyperaldosteronism Premenstrual syndrome Polycystic ovary syndrome Acne in young women
spironolactone AE
hyperkalemia
benign and malignant tumors
endocrine effects
spironolactone AE
thiazide and loop diuretics
agents that raise K levels
triamterene
Mechanism of action Disrupts sodium-potassium exchange in the distal nephron Direct inhibitor of the exchange mechanism Decreases sodium reuptake Inhibits ion transport Therapeutic uses Hypertension Edema
Adverse effects Hyperkalemia Leg cramps Nausea Vomiting Dizziness Blood dyscrasias (rare)
