c41: diuretics
lasix MOA
Acts on ascending loop of Henle to block reabsorption of NA+ and CL-
Are there any other steps the nurse should take regarding IV administration of mannitol?
Along with following all the appropriate safety precautions for medication administration, the nurse should use a filter needle to withdraw mannitol from the vial, as well as an in-line filter for IV infusion, to prevent crystals from entering the circulation.
Spironolactone [Aldactone] MOA
Blocks aldosterone in the distal nephron Retains potassium Increases excretion of sodium
Three basic functions of diuretics
Cleansing of extracellular fluid (ECF) and maintenance of ECF volume and composition Maintenance of acid-base balance Excretion of metabolic wastes and foreign substances
Hydrochlorothiazide [HydroDIURIL] drug interactions
Digoxin 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
lasix drug interactions
Digoxin: hypokalemia and dig-induced toxicity Ototoxic drugs: any ototoxic drugs, especially aminoglycosides Potassium-sparing diuretics: help to counter the potassium loss Lithium: Lithium toxicity related to lower sodium levels (reduces lithium levels) Antihypertensive agents: reduced BP Nonsteroidal anti-inflammatory drugs: NSAIDs inhibit prostaglandin synthesis leading to reduced renal blood flow, partially blunting the diuretic effect of furosemide
triamterene (dyrenium) MOA
Disrupts sodium-potassium exchange in the distal nephron Direct inhibitor of the exchange mechanism Decreases sodium reuptake Inhibits ion transport
other high ceiling (loop) diuretics
Ethacrynic acid [Edecrin] Bumetanide [Bumex] Torsemide [Demadex] All can cause: Ototoxicity, hypovolemia, hypotension, hypokalemia, hyperuricemia, hyperglycemia, and disruption of lipid metabolism
three basic renal processes
Filtration: Occurs at the glomerulus Reabsorption - 99% of water, electrolytes, and nutrients undergo reabsorption Active tubular secretion - Proximal convoluted tubule
Spironolactone [Aldactone] adverse effects
Hyperkalemia Endocrine effects (spironolactone is a steroid derivative) - Gynecomastia (breasts in men), menstrual irregularities, impotence, hirsutism, deepening of the voice
Triamterene [Dyrenium] adverse effects
Hyperkalemia - Use caution when giving with other diuretics, ACE inhibitors, and renin inhibitors Leg cramps Nausea Vomiting Dizziness Blood dyscrasias (rare)
Spironolactone [Aldactone] therapeutic uses
Hypertension Edematous states Heart failure (decreases mortality in severe failure) Primary hyperaldosteronism Premenstrual syndrome Polycystic ovary syndrome Acne in young women
Hydrochlorothiazide [HydroDIURIL] adverse effects
Hyponatremia, hypochloremia, and dehydration Hypokalemia Use in pregnancy and lactation Hyperglycemia Hyperuricemia Impact on lipids, calcium, and magnesium
lasix adverse effects
Hyponatremia, hypochloremia, and dehydration Hypotension - Loss of volume - Relaxation of venous smooth muscle Hypokalemia Ototoxicity ALERT!! To avoid ototoxicity, infuse no more than 4mg/minute!!* Hyperglycemia Hyperuricemia (from elevated plasma uric acid) Use in pregnancy Impact on lipids, calcium, and magnesium - Reduces HDL, raises LDL, cholesterol, and triglycerides - Increases excretion of calcium (may be used to treat hypercalcemia) - Increases excretion of magnesium (may cause muscle weakness, tremor, twitching, and dysrhythmias *safety alert: excessive loss of sodium, chloride, and water. Severe dehydration can result. Dehydration can promote hypotension, thrombosis, and embolism*
diuretics adverse effects
Hypovolemia Acid-base imbalance Electrolyte imbalances
classification of diuretics four major categories
Loop: Furosemide Thiazide: Hydrochlorothiazide Osmotic: Mannitol Potassium-sparing: Two subcategories - Aldosterone antagonists (spironolactone) - Nonaldosterone antagonists (triamterene) Fifth group - Carbonic anhydrase inhibitors
Mannitol IV has been ordered for the patient. When the IV solution of mannitol arrives from the pharmacy, the nurse notes crystals in the fluid. What is the most appropriate action by the nurse?
Mannitol may crystallize out of solution if exposed to a low temperature. Accordingly, preparations should be observed for crystals before use. Preparations that contain crystals should be warmed (to redissolve the mannitol) and then cooled to body temperature for administration.
lasix therapeutic uses
Pulmonary edema Edematous states Hypertension
furosemide (Lasix)
Most frequently prescribed loop diuretic
Mannitol [Osmitrol] therapeutic uses
Prophylaxis of renal failure Reduction of intracranial pressure Reduction of intraocular pressure
diuretics site of action
Proximal tubule produces greatest diuresis
lasix pharmacokinetics
Rapid onset (PO 60 min; IV 5 min; IM unknown) IV don't use if discolored give slowly over 1-2 minutes, for infusion For infusion - dilute with D5W, NSS, or LR. Use solution in 24 hours ALERT!! To avoid ototoxicity, infuse no more than 4mg/minute!! Hepatic metabolism and renal excretion
A patient who sustained a head injury is admitted to the critical care unit with increased intracranial pressure (ICP). The healthcare provider says that a diuretic will be used to lower the patient's ICP. The nurse anticipates that which diuretic will be ordered, and why?
The nurse anticipates that mannitol, an osmotic diuretic, will be ordered. Intracranial pressure (ICP) that has been elevated by cerebral edema can be reduced with mannitol. The drug lowers ICP because its presence in the blood vessels of the brain creates an osmotic force that draws edematous fluid from the brain into the blood. There is no risk of increasing cerebral edema because mannitol cannot exit the capillary beds of the brain.
potassium sparing diuretics
Useful responses - Modest increase in urine production - Substantial decrease in potassium excretion Rarely used alone for therapy Aldosterone antagonist - Spironolactone Nonaldosterone antagonist - Triamterene
Spironolactone [Aldactone] drug interactions
thiazide and loop diuretics agents that raise potassium levels
When providing discharge teaching for a patient who has been prescribed furosemide [Lasix], it is most important for the nurse to include which dietary items to prevent adverse effects of furosemide [Lasix] therapy? a. Oranges, spinach, and potatoes b. Baked fish, chicken, and cauliflower c. Tomato juice, skim milk, and cottage cheese d. Oatmeal, cabbage, and bran flakes
a. oranges, spinach, potatoes Furosemide may have the adverse effect of hypokalemia. Hypokalemia can be reduced by consuming foods that are high in potassium, such as nuts, dried fruits, spinach, citrus fruits, potatoes, and bananas.
A patient with heart failure who takes furosemide [Lasix] is diagnosed with bacterial pneumonia. Which medication, if ordered by the physician, should the nurse question? a. Ciprofloxacin [Cipro] b. Gentamicin [Garamycin] c. Amoxicillin [Amoxcil] d. Erythromycin [E-Mycin]
b. gentamicin (garamycin) High-ceiling loop diuretics may cause hearing impairment; furosemide may result in deafness that is transient. Because of the risk of hearing loss, caution is needed when high-ceiling diuretics are used in combination with other ototoxic drugs (for example, aminoglycoside antibiotics). Gentamicin is an aminoglycoside. The other antibiotics are safe to administer with furosemide.
diuretics MOA
blockade of sodium and chloride reabsorption
A patient is prescribed spironolactone [Aldactone] for treatment of hypertension. Which foods should the nurse teach the patient to avoid? a. Baked fish b. Low-fat milk c. Salt substitutes d. Green beans
c. salt substitutes Spironolactone is a potassium-sparing diuretic. Medications that are potassium sparing, potassium supplements, and salt substitutes should be avoided. High-potassium foods should also be avoided.
The nurse cares for a patient who is prescribed oral furosemide (Lasix) once daily. It is most important for the nurse to take which action? a. Monitor the patient for signs and symptoms of hyperkalemia. b. Insert a urinary catheter and assess the hourly urine output. c. Weigh the patient every week. d. Schedule the medication to be given at 0800.
d. schedule the medication to be given at 0800
mannitol (osmitrol) pharmacokinetics
drug must be given parenterally
hydrochlorothiazide (hydroDIURIL) (HCTZ) action
early segment distal convoluted tubule peaks in 4-6hrs
Mannitol [Osmitrol] adverse effects
edema headache nausea vomiting fluid and electrolyte imbalance
Hydrochlorothiazide [HydroDIURIL] therapeutic uses
essential hypertension edema diabetes insipidus (excessive production of urine)
four functionally distinct regions of the nephron
glomerulus proximal convoluted tubule loop of henle distal convoluted tubule
Triamterene [Dyrenium] therapeutic uses
hypertension edema
functional unit of a kidney
nephron
mannitol (osmitrol)
osmotic diuretic (large sugar molecule) Promotes diuresis by creating osmotic force within lumen of the nephron
benzothiadiazides effects
similar to those of loop diuretics 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)