Flashcards in Ionotropic Drugs: Limitations in Heart Failure Deck (24)
What does digoxin do?
decrease chronotropy/ increase ionotropy (weak)
1. ^ baroreceptor activity > blocks NE > shuts off sympathetic system >> decreased HR
2. Blocks Na/ K ATPase > increase intracellular Na > less Ca exchanged out of cell >> more Ca
How is digoxin excreted?
-careful with patients with renal dysfxn
-long half life - 7 days to steady state!
-metabolism = P-glycoprotein
It's important to monitor digoxin, what serum levels are desired (and don't kill patient)?
.5 - 1 ng/ml
Who would you give digoxin to?
-Patients with HFrEF, who aren't responding well to treatment with ACEI/ ARBs, Beta blockers, diuretics
-All patients with sever HF symptoms
-No benefit in HFpEF!
When do you check digoxin serum levels?
7 - 14 days after starting therapy
What are the toxicities with digoxin?
-Heart block, bradycardia, arrythmia
-seeing blue/ green halos
How does taking antiarrythmics affect your digoxin dosing?
They inhibit P-gp
-you should reduce digoxin dose by 50%
What other medications can adversely affect digoxin levels?
-Calcium channel blockers (verapamil)
*inhibitors of P-gp
Induces: rifampin, St. John's Wort
What effects do potassium, calcium, and magnesium have on digitoxin toxicity?
What medication can you give in the ER to someone who has digoxin toxicity?
Digoxin immune fab (ovine)
What happens if you stop digoxin treatment instantly?
T/F: Digoxin reduces mortality
False- only reduces hospitalization
Name the two big inotrope medications
What patients generally get inotropic medicine?
Class III - "cold and dry" (hypoperfusion)
Class IV - "cold and wet" (hypoperfusion and congestion)
Contrast the biochemical mechanism of action of milrinone and dobutamine?
Milrinone: inhibits PDE > accumulation of Ca
Dobutamine: B1 agonist to stimulate G proteins > increase Ca
With each of the following, does milrinone or dobutamine have a stronger effect?
2) enhanced inotropy
3) increased heart rate
Are inotropes for short-term or long-term use?
Which inotrope has a shorter half life?
=Dobutamine: 2 minutes
-more rapid onset/ clearing
Milrinone: 1- 3 hours
-cleared by kidneys
If you have a hypotensive patient, which inotrope would be better?
*milrinone has more moderate vasodilation
If your patient is taking beta blockers, which inotrope would you use?
*dobutamine is a beta agonist
According to the Heart Failure Society of America, when should you consider giving inotropes?
-Patients with advanced HF and low output syndrome
-patients have marginal BP ( to relieve symptoms and improve end-organ function
**NOT LONG TERM
**MAKES THEM FEEL BETTER, BUT NO BETTER OUTCOMES
Side effects of both?
Milrinone: HYPOTENSION, thrombocytopenia, tachycardia, arrythmia
Dobutamine: Angina, tachyarrythmia
Alright Dopamine is also an inotrope, but we didn't talk about it much. How does it work?
Norepinephrine precursor > stimulates adrenergic receptors