Week 1 Cardiac Pharm 2 of 4 Flashcards
What is the endogenous central and peripheral neurotransmitter that is derived from dopa in the chain of catecholamine synthesis?
Dopamine
Dopamine Doses
–Dopamine receptors: 2 mcg/kg/min
–Beta: 2-5 mcg/kg/min
–Alpha: 10 mcg/kg/min and above
What has indirect sympathomimetic effect eliciting the release of norepinephrine via Beta 1 stimulation?
Dopamine
Often chosen for patients in shock?
Dopamine (but more often norepi)
■May have poor response in cases of gram-negative sepsis b/c of a down regulation in which the sensitivity of beta receptors is diminished
Dopamine
■Used in the past periop for “renal dose” dopaminergic effects to increase UOP however has been abandoned by some d/t long-term morbidity and mortality are not improved. This drug also inhibits aldosterone resulting in an increase in sodium excretion and UOP
Dopamine
■Dopamine has been implicated in limb ischemia in what patients?
■Dopamine has been implicated in limb ischemia in:
–Pediatric patients
–Vascular diseases such as:
■Diabetes
■Atherosclerosis
■Raynaud’s
–Presence of an artline in the affected limb also increases incidence of limb ischemia with concurrent dopamine administration
What is Isoproterenol?
■Synthetic catecholamine
■Potent non-selective agonist of Beta 1 and Beta 2 receptors
■Has no agonistic activity at alpha or dopamine receptors
What is Isoproterenol’s clincal use?
■Can be seen used in:
–Brady with heart block
–Torsades de points
–VT
–After heart transplant for chronotropic support (Beta 2 receptor stimulation)
Profound Beta 1 stimulation results in both positive _______ and _______ effects in Isoproterenol.
■Profound Beta 1 stimulation results in both positive inotropic an chronotropic effects
What happens to the cardiac output in Isoproterenol?
■Increase in CO is seen due to combination B1 and B2 inducing vasodilation and resultant drop in SVR
■In IIsoproterenol, the positive inotropic and chronotropic effect results in a dramatic increase in ______________________.
■The positive inotropic and chronotropic effect results in a dramatic increase in myocardial oxygen consumption
■This is in addition to a probable already existing compromise due to the Beta 2 induced peripheral vasodilation causing a decrease in DBP and ultimately a decrease in coronary artery perfusion
■Isoproterenol is a also a potent ______ _____ and ____ _____.
■Isoproterenol is a also a potent bronchial dilator and pulmonary vasodilator
What detrimental effects does Isoproterenol have on the heart?
■Detrimental effects on the heart limiting its use:
–Excessive tachy
–Myocardial ischemia
–Arrhythmia production
What is Dobutamine?
■Synthetic sympathomimetic amine
■Modified isoproterenol but is used widespread
■Primarily Beta 1 agonist with some Beta 2 effects
■Strong inotropic response with minimal chronotropy
■Produces slight drop in SVR b/c of peripheral vasodilation
■Increase in CO compensates for decrease in SVR and the BP is increased (or at low doses relatively unchanged)
■With the use of Dobutamine, pulmonary artery pressure______ and an _______ in LV stroke work index is observed
With the use of Dobutamine, pulmonary artery pressure decreases and an increase in LV stroke work index is observed
What 3 reason is Dobutamine an option in cardiogenic and septic shock and in select patient with mild heart failure?
■Is an option in Cardiogenic and Septic shock and in select patient with mild heart failure because:
–Positive inotropic effects
–Lack of chronotropy
–Maintenance of normal BP
What drug is ised for heart stimulation for cardiac stress test?
Dobutamine?
■Recent evidence indicates significant adverse effects when this drug is used in cardiac surgery and clinicians have stopped using it for inotropic support.
Dobutamine
Most commonly used purely alpha agonist?
■Has strong alpha stimulating effect with virtually no beta stimulation
■Sharp rise in BP is produced as a result of a significant increase in peripheral resistance secondary to alpha 1 stimulation
Phenylephrine
What drug can cause Reflex bradycardia can be elicited secondary to baroreceptor stimulation?
Phenylephrine
Must be vigilant in dosing. Can cause large changes in increasing BP and decreasing HR.
Phenylephrine
Onset is immediate with 5-20 minute duration.
Phenylephrine
■Topical doses should not exceed 0.5 mg (4 drops of 0.25% in adults) and 20 mcg/kg in children in order to prevent severe hypertension
Phenylephrine
What class of drug is Milrinone?
Phosphodiesterase Inhibitors
■Produces a positive inotropic action and vasodilation without producing tachycardia
Milrinone
Which drug
–Substantially improves LV function in association with acceleration of calcium uptake by the sarcoplasmic reticulum
–This acceleration appears to result from an inhibition of membrane-bound PDE3 in the sarcoplasm, which induces a local elevation of cAMP.
–This allows a build-up of cAMP and a subsequent increase in the uptake of intracellular calcium
Milrinone
What drug ■Improves weaning of high risk patients from cardiopulmonary bypass?
Milrinone
What is the clinical result of milrinone?
■Clinical result is a decrease in both preload and afterload
■These effect along with absence of an increase in HR probably contributes to an absence of myocardial oxygen consumption
Which drug ■Acts to enhance diastolic function, increases cardiac output and decreases pulmonary wedge pressure?
Milrinone
Side effects of Milrinone?
Arrythmias
MIlrinone elimination?
Kidneys
Loading Dose of Milrinone?
■Loading Dose:
–50 mcg/kg slowly over 10 minutes
Infusion rate that is started after initial loading dose of Milrinone?
■Loading Dose:
–50 mcg/kg slowly over 10 minutes
■Followed by infusion:
–0.5 mcg/kg as needed
Ephedrine is a ______ ______ _____.
mixed function agonist
What drug
■Synthetic non-catecholamine sympathomimetic
■Stimulates both alpha and beta receptors directly
■Indirectly causes release of endogenous catecholamines, leading to a multiple mechanisms of action
■Acts centrally and peripherally
■Effects similar to epi but to a lesser degree and not accompanied with dramatic increase in serum glucose
Ephedrine?
What drug
■Duration is longer than epi due to lack of basic catechol structure so it’s resistant to metabolism by monoamine oxidase
■Produces dose related increase in BP, CO, HR and SVR
■Usually first sympathomimetic chose for alleviation of hypotension due to cardiac depressant effects of anesthetic agents or vasodilation resulting from spinal anesthesia
Ephedrine
