Week 5 - Cardiac continued Flashcards
Mechanism of Cardiac Glycosides `
Inhibit sodium/potassium pump to increase intracellular Calcium during depolarization
What effect do cardiac glycosides have on the conduction of SA to AV?
Slows conduction - Always check HR before giving!
Cardiac Glycoside have: \_\_\_\_\_\_\_ inotropic effect \_\_\_\_\_\_\_ chronotropic effect \_\_\_\_\_\_\_ dromotopic effect \_\_\_\_\_\_\_ stroke volume \_\_\_\_\_\_\_ cardiac output \_\_\_\_\_\_\_ peripheral and lung fluid retention \_\_\_\_\_\_\_ fluid excretion
- Positive inotropic effect
- Negative chronotropic effect
- Negative dromotopic effect
- Increases stroke volume
- Increases cardiac output
- Decreases peripheral and lung fluid retention
- Increases fluid excretion
Indications for cardiac glycosides
CHF, A Fib/flutter, paroxysmal atrial tachycardia
Cardiac glycoside prototype
Digoxin (Lanoxin)
Digoxin dosage (PO, IV, Elderly, children )
PO: 0.5 - 1mg initially in 2 divided doses (digitalization) , then 0.125 - 0.5 mg/day for maintenance
IV: same as PO but given over 5 min
Elderly: 0.125 mg/day
Children: Doses are ordered in mcg in elixir form
Digoxin absorption (Oral, Liquid)
Oral: 60-70%
Liquid: 90%
Digoxin distribution (protein bound and its implication)
LOW protein bound - means there is a lot of active form circulation and thus higher risk for toxicity
Digoxin half life
30-40 hours
Digoxin excretion
70% urine through kidney - thus higher risk for toxicity in renal patients
30% by liver metabolism
Quinidine, Verapamil, Flecainide ______ serum digoxin levels
Increase serum digoxin levels
Antacids _____ digoxin levels by
Antacids decrease digoxin levels by decreasing absorption
Thiazides and loop diuretics ______ risk for toxicity because
Increase risk for toxicity because they can cause hypokalemia, which intensifies effects of digitalis
Hypomagnesemia, hypercalcemia _____ risk for toxicity
Increase risk for toxicity
Hypokalemia _____ effects of digitalis
Hypokalemia intensifies effects of digitalis
Digoxin and Ginseng
Ginseng - falsely elevates digoxin levels
Digoxin and St. John’s Wort
St. John’s Wort - decreases absorption and thus serum level
Digoxin and Hawthorn
Hawthorn - increases effect of digoxin
Digoxin and Aloe
Aloe - increases potassium loss, causing hypokalemia which can lead to digitalis toxicity
Digoxin and Ma Huang
Ma Huang - increases risk for toxicity
Digoxin and Licorice
Licorice - potentiates effects of digoxin
Therapeutic serum level of Digoxin
0.5 - 2.0 ng/mL
The therapeutic serum level is _______. This plus the low PB indicates ______ risk for ______.
The therapeutic serum level is narrow. This plus the low PB indicates high risk for toxicity.
Signs and symptoms of digitalis toxicity (8)
*Bradycardia, PVC, cardiac dysrhythmias,visual disturbances (green and yellow halos), blurred vision, confusion/delirium H/A, N/V
Who are at greater risk for digitalis toxicity?
Elderly and renal patients
When giving digoxin, always check (4)
- Serum potassium
- Baseline apical pulse rate (do not give if below 60)
- BUN and creatinine
- Signs and symptoms of toxicity
Carvedilol (Coreg) classification
3rd generation Beta blocker (beta receptor antagonist) - NON-selective
Carvedilol mechanism
-Blocks beta 1, beta 2, alpha 1
It’s an ANTIOXIDANT
-Protects against free radicals causing damage to nucleic acids, proteins, and lipids (which are linked to CAD, atherosclerosis)
-Protects from further inflammatory damage or change
Carvedilol is NOT for… (4)
COPD, CHF, Asthma, DM
When should Carvedilol be given?
Early stages of HF to slow progression to CHF
What is the primary line of therapy for majority of patients with HF?
Diuretics
Three categories of diuretics
Thiazides, Loop, Potassium sparing
Diuretic mechanism
Produce net loss of sodium and water acting directly on the kidney to decrease acute symptoms of HF that result from fluid retention (such as dyspnea, edema)
Thiazide mechanism
Inhibits active transport of Cl-Na in the cortical diluting segment of the ascending limb of the Loop of Henle
Thiazide example
Hydrochlorothiazide (HCTZ)
Loop mechanism
Inhibits active transport of Cl-Na-K in the thick portion of the ascending limb of the Loop of Henle
Loop example
Furosemide (Lasix)
Potassium sparing mechanism
- Inhibits REABSORPTION of Na in the distal convoluted and collecting tubules
- BLOCKS aldosterone production
What kind of effect do potassium sparing diuretics have on the heart?
Cardioprotective effect - blocks aldosterone in the heart and blood vessels to promote cardiac remodeling (repair inflammation)
What can use of potassium sparing diuretics lead to?
Hyperkalemia
Potassium sparing example
Spironolactone (Aldactone)
What is carbonic anhydrase?
Enzymes found in the proximal convoluted tubule in the kidney that helps maintain balance of hydrogen ion and bicarbonate in our bodies
Carbonic Anhydrase Inhibitors - mechanism
Inhibits action of carbonic anhydrase - causes Na, K, HCO excretion to make pH of kidney tubules alkaline and alkalinizes the urine
Carbonic Anhydrase Inhibitors - uses (2)
- Primarily used to decrease IOP in chronic open angle glaucoma
- Can also alkalinize urine in rhabdomyolisis (alkalinizing = protects integrity of tubules)
Carbonic Anhydrase Inhibitor protoype
Acetazolamide (Diamox)
Acetazolamide (Diamox) classification
Carbonic Anhydrase Inhibitor
Acetazolamide (Diamox) side effects (5)
Fluid and electrolyte imbalances, metabolic acidosis, N/V, confusion, orthostatic hypotension
Acetazolamide (Diamox) adverse reactions (3)
Hemolytic anemia, renal calculi, crystalluria
Osmotic Diuretic mechanism
Pulls large amounts of fluid into the urine by osmotic effect
Osmotic Diuretic uses (2)
- Decrease IOP or intracranial pressure
- Prevent kidney failure in Cisplatin chemotherapy
Osmotic Diuretic prototype
Mannitol (Osmitrol)
Mannitol mechanism
As a sugar, pulls large amounts of fluid into the urin by osmotic pull of the sugar
Mannitol side effects (3)
N/V, fluid and electrolyte imbalance, pulmonary edema
Mannitol contraindications (2)
- HF - because if you’re increasing intravascular volume, you further congest the HF patient
- Renal Failure - they’re not making urine so they cannot get rid of the fluid you’re pulling out
Mannitol can ______ in vial if exposed to ________. Do not infuse if ______ are present.
Mannitol can crystallize in vial if exposed to low temperature. Do not infuse if crystals are present.
