Inotropesfs

INTRODUCTION
 An inotrope is an agent, which increases or decreases
the force or energy of muscular contractions.
 In 1785 the first inotrope-Digitalis was discovered &
used for CCF.
 As science advanced, other inotropes were developed
which were more potent and have different chemical
properties and physiological effects.
 All inotropes are successful because they increase the
myocardial contractility of the heart.
 By enhancing myocardial contractility, cardiac output, the
amount of blood ejected by the heart with each beat,
will also increase.

Three clinically approved
inotropes
Cardiac Glycosides: - Digitalis Derivatives
Digoxin
Sympathomimetics: -
Epinephrine
Dopamine (Intropin)
Dobutamine (dobutrex)
Norepinephrine (levophed)
Isoproterenol (isuprel)
 Phosphodiesterase Inhibitors: -
Amrinone (Inocor)
Milirinone (Primacor)

CARDIAC GLYCOSIDES
The first line of inotropes include all
digitalis derivatives
Digitalis Glycosides have
A direct effect on cardiac muscle and the
conduction system.
An indirect effect on the cardiovascular
system regulated by the
 autonomic nervous system which is
responsible for the effect on the sino-
atrial (SA) and atrioventricular (AV)
nodes.

The result of these direct and indirect
effects are: -

An increase in force and velocity of
myocardial contractility (positive
inotrope effect).
Slowing of heart rate (negative
chronographic effect).
Decreased conduction velocity through
the AV node.

DIGOXIN

Digoxin is the most commonly prescribed cardiac
glycoside
 Convenient pharmacokinetics,
 Alternative routes of administration
 Widespread availability of serum drug level
measurement.

DIGOXIN ADMINISTRATION

Digoxin can be administered intravenously
or orally.
IV injection should be carried out over 15
minutes to avoid vasoconstriction
responses.
Intramuscular Digoxin is absorbed
unpredictably, causing local pain, and is not
recommended.

DIGOXIN LOADING DOSE

 Loading doses of Digoxin range from 10 –
15mg/kg.

 Digoxin can be given orally, but with a slower
onset of action and peak effect.

DIGOXIN MAINTENANCE DOSE :-
Initial therapy of Digoxin is usually started at
0.125 to 0.375mg/day.

NOTE: DRAW A SERUM DIGOXIN LEVEL AT
LEST SIX HOURS AFTER THE LAST DOSE!

SIDE EFFECTS ASSOCIATED WITH
TOXICITY:-

 GASTROINTESTINAL : Anorexia, nausea,
vomiting, diarrhea Rare: abdominal
pain, hemorrhagic necrosis of the
intestines.

 CNS : visual disturbances, (blurred or
yellow vision), headache, weakness,
dizziness, apathy and psychosis.

 OTHER : Skin rash, gynecomastia

SYMPATHOMIMETICS (ADRENERGIC)

Sympathomemetic drugs exert
potent inotropic effects by
stimulating beta (B1 and B2), alpha
(A1 and A2) and dopaminergic
receptors in the myocardium, blood
vessels, and sympathetic nervous
system.

ALPHA 1 (A1):

 A1 receptors are in vascular smooth muscle &
also in the myocardium, which mediate positive
inotropic and negative chronotropic effects.

 Stimulation of A1 receptors leads to
vasoconstriction.

ALPHA 2 (A2):-
 A2 receptors are located in large blood vessels.

 Stimulation of A2 receptors mediates arterial and
venous vasoconstriction.

BETA 1 (B1):-

Beta 1 receptors increase heart rate and myocardial
contractility.

BETA 2 (B2):-

Beta 2 receptors enhance vasodilation; relax
bronchial, uterine and gastrointestinal smooth
muscle

DOPAMINERGIC: Related to the effect of
dopamine.

DOPAMINE (INTROPIN)
(200mg/5ml ampule).

A chemical precursor of epinephrine.

 Possessing alpha and beta and dopaminergic
receptor – simulating actions.

The specific effects are related to the dose
delivered.

LOW DOSE
0.5- 2mcg/kg/minute (Dopaminergic effect).

Vasodilation of renal and mesenteric arteries.

Promote blood flow and increased GFR
(glomerular filtration rates in patients who
become resistant to diuretics).

Urine output may increase without significant
effect on blood pressure or heart rate.

INTERMEDIATE DOSE
2 to 10 mcg/kg/minute

Beta-adrenergic receptor activity is
increased in the heart.

Partial antagonism of alpha –
adrenergic receptors will mediate
vasoconstriction.

Modest increase in systemic vascular
resistance increases cardiac output
& CVP

DOPAMINE ADMINISTRATION
CONCENTRATIONS

Remove 5ml from 100ml 5% Glucose ,add
200 mg Dopamine, final concentration
2000mcg/ml.

OR

Make the concentration half with 50 ml
of 5% Dextrose.

Indication:-
 Renal protection.
 Hypotention/haemodynamic
compromise due to MI, trauma,
sepsis, CCF.
 Increases mesenteric flow in
mesenteric ischaemia.

Contraindication: -
Pregnancy.
Phaeochromocytoma.
Tachyarrhythmias.
Occlusive vascular disease.

WARNING:
Correct hypovolaemia prior to administration.
 Do not infuse peripherally.
 Extravasations can cause severe tissue necrosis.
 Monitor the patient carefully for decreased
circulation in the extremities.

If extravasates into tissues-
The infusion should be immediately stopped.
Infiltrate with 0-15ml 0.9% Sodium Chloride
containing 5-10mg Phentolalmine.
Regitine is then administered SQ in the four
90°quadrants around the site of extravasations.

ADVERSE EFFECTS:
Tachycardia
Supraventricular tachycardia
Ventricular arrhythmias
Pulmonary congestion
Nausea
Vomiting
Headache.
Increased myocardial oxygen demand.
Hypotension when used concomitantly
with dilantin

DOBUTAMINE (Dobutrex)
(250mg in 20ml ampule)
• Drug class:-
Catecholamine.
• Mechanism of action:-
 Chemically related to dopamine.
 Synthetic catecholamine.
 Stimulates Beta 1 and Alpha-adrenergic
receptors.
 Increases myocardial contractility, stoke volume
and cardiac output.
 Decreases preload and afterload (Vasodilatation)
 Produces mild chronotropic, hypotensive and
arrhythmogenic effects.
 Increase renal and mesenteric blood flow by
increasing cardiac output.
 Does not affect renal blood flow like dopamine.

• Initial dose: -
2 to 3 mcg/kg/minute.
• Usual dose: -
2.5 to 10 mcg/kg/minute.
• Desired effects include:
1. Increased cardiac output
2. Increased stroke volume
This dose will not increase heart rate
or cause vasoconstriction.

Maximum dose: -
20 mcg/kg/minute.
Dobutamine administration
concentrations: -
Infusion pump: 500 mg per 250 cc
normal saline
Syringe pump: 250 mg (20cc) in
total 50 cc normal
saline (5 mg per cc)

• Contraindication:-
Idiopathic hypertrophic subaortic
stenosis.
• Nursing implication: -
Monitor for hypertension, tachycardia, chest
pain, and premature ventricular contractions.
Monitor cardiac output, pulmonary artery
pressure ECG
Correct hypovolemia before treating with this
drug.
Patient with aterial fibrillation should be
digitalized before giving this drug to prevent
ventricular tachycardia.

Warning: -
Increasing the rate past 20
mcg/kg/minute could be detrimental
because myocardial oxygen
consumption can cause tachycardias.
Adverse effects:-
 Tachycardia
 Arrhythmias
 Blood pressure fluctuation
 Myocardial ischemia
 Headache
 Nausea
 Tremors
 Hypokalemia

NOREPHINEPHRINE (LEVOPHED)

Drug class: -
 Catecholamine.
 Endogenous catecholamine released from nerve cells,
synthesized by adrenal medulla.
 Metabolized mainly by the liver.
Mechanism of action: -
Potent alpha – receptor antagonist, leads to arterial and
venous constriction.
Minimal effect on beta 2 receptors.
Increases myocardial contractility due to its beta 1
adrenergic effects.
Effective in septic shock and neuroginic shock after
adequate hydration.
Increases blood flow to the major organs including the
kidneys and helps in increases urine output.

Initial dose: -
0.5 mcg/minute to 1 mcg/minute
Titrate to desired effect
 Average dose:-
2 to 12 mcg/minute
Doses greater than 30 mcg/minute
might be required during shock.
Norepinephrine administration
concentration:-
Infusion pump: 4 mg per 250 c crystalloid
(16 mcg/cc)

Contraindications:-
Hypovolemic and cardiogenic shock
(because potent vasoconstriction is
already occurring).
Pregnancy.
Hypoxia.
Hypovolemia secondary to fluid
deficit.
Caution with hypertension and
hyperthyroidism.

Nursing implication:-

Extravasations produces ischemic
necrosis and sloughing of superficial
tissues.
Use of a central line is recommended
due to the risk of extravasations into
surrounding tissue.
Rebound hypotension occurs if it is
discontinued abruptly.
Its use should be temporary.
Monitor for bradycardia or
arrhythmias.

EPINEPHRINE
• Drug class: -
Catecholamine.
Endogenous catecholamine, produced,
stored, and released by the adrenal medulla.
Mainly eliminated via kidneys.
• Mechanism of action: -
Stimulation of alpha and beta-adrenergic
receptors causes vasoconstriction.
Increases heart contractility and rate.
Causes bronchodilation.
Antagonizes histamine effect.

• Dosage: -
Initial dose 0.5-1mg IV.
Or
1.5-3mg via ETT.
Maintain drip of 1-4 mcg/minute.
Titrate to BP.
Common contraindication: -
Hypertension.
Pheochromocytoma.
Caution with heart failure angina and
hyperthyroidism.

Adverse effects: -
 Cardiac Arrhythmias
 Palpitations
 Tachycardia
 Sweating
 Nausea and vomiting
 Respiratory difficulty
 Pallor
 Dizziness
 Weakness
 Tremors
 Headache
 Apprehension
 Nervousness
 Anxiety
Nursing implication: -
 Monitor ECG.
 Observe for ventricular ectopy.

ISOPROTERENOL (ISUPREL)

 Has nearly pure beta-adrenergic receptor activity.
 Increase heart rate and contractility and cause
peripheral vasodilation.
 Used for temporary control of symptomatic
bradycardia.
 Initial drug of choice for heart transplant.
 Increases myocardial oxygen requirements and the
possibility of inducing or exacerbating myocardial
ischemia is present.
 The risk of arrhythmias is also increased.
 It is not the first treatment of choice for
bradycardias.
• Atropine, epinephrine or pacing should
be initiated first.

DOSE: -
 Initial dose of 2 mcg/minute
 Titrate dose to a maximum of 10 mcg/min.
or heart rate is 60 or greater.
 Decrease the rate if blood pressure is
>120/60
 Decrease rate if PVC’s or Ventricular
tachycardia is noted.
Isoporterenol administration
concentration: -
 1 mg in 250 cc crystalloid (4 mcg/cc).

Adverse effects: -
Arrhythmias.
Ventricular tachycardia.
Ventricular fibrillation.
Warning :-
 May exacerbate tachyarrhythmias
due to digitalis toxicity.
 May precipitate hypokalemia.

PHOSPHODIESTERASE INHIBITORS
Powerful positive inotropic agents.
The action is not fully understood.
 Inhibits phosphodiesterase, an enzyme that degrades
(CAMP)
 Cyclic Adenosine Monophosphate.
 There is no effect on alpha or beta-receptors.
 Increase contractile force and velocity of relaxation of
cardiac muscle.
 Increasing cardiac output without increasing myocardial
 oxygen consumption.
 They cause vasodilation and a decrease in SVR (systemic

 vascular resistance) and PVR (Pulmonary vascular
 resistance & in afterload (resistance to ventricular
ejection)

AMRINONE (INOCOR)

Has a hemodynamic effect similar to Dobutamine.
Increase cardiac output and decrease pulmonary
vascular resistance.
It should be used with caution in patients with
ischemic heart disease because it can exacerbate
ischemia.
It should be considered for use in patients with severe
congestive heart disease, which is no longer
responsive to other inotropes, diuretics, and
vasodilators.
 It is also used after aorto-coronary bypass surgery.
 It is recommended that the lowest dose that produce
the desired hemodynamic effect to be used.

LOADING DOSE:
0.5 TO 0.75 mg/kg given over 2-3 min. IV

DO NOT EXCEED 1 mg/kg.

Maintenance dose: -
5 to 10 mcg/kg/min

Maximum dose:-
10mg/kg/24hours.
Doses higher than 15 mcg/kg/minute
can produce tachycardia

NEVER DILUTE WITH DEXTROSE !
---Chemical reaction occurs

Syringe pump: Use Straight Solution
Concentration 5 mg/cc

Adverse reaction: -
Thrombocytopenia occurs in 10% of all
patients seen 48 – 72 hours after
infusion and resolves when drug is
discontinued.
Gastrointestinal upset
Myalgia
Fever
Hepatic dysfunction
Ventricular irritability

Nursing implication: -
Monitor for arrhythmias, hypotension,
thrombocytopenia & hepatotoxicity.

Monitor cardiac output, pulmonary
artery pressure and heart rate.

Effects last for 2 hours after drip is
discontinued.

The loading dose may be given over 2 to
5 minutes, but to prevent Hypotension
it is recommended the loading dose be
given over 10 to 15 minutes.

MILRINONE (Primacor)

Milrinone is about 10 fold more potent
than Amrinone.
A positive inotropic agent that
increases cardiac output and decreases
systemic vascular resistance.
Because of its vasodilating effect,
Milrinone is not generally associated
with an increase in myocardial oxygen
demand.
Milrinone can be diluted in dextrose or
saline solution.

LOADING DOSE:-
50 mcg/kg given IV over 10 minutes

MAINTENANCE DOSE:-
0.375 to 0.75 mcg/kg/minute

Warning; -
DOSES TO HIGH CAN CAUSE
HYPOTENSION AND TACHYCARDIA.

MILRINONE IS INCOMPATIBLE
WITH LASIX!
ADVERSE EFFECTS:
Supraventricular tachycardia
Ventricular arrhythmias
Ventricular ectopy
Increased ventricular rate in atrial
fibrillation/flutter
Headache
Hypokalemia
Tremors
Thrombocytopenia

EASY FORMULAS FOR DRUG CALCULATIONS FOR
INFUSION PUMPS

TO DETERMINE DESIRED RATE:-

(Remember 1 mg = 1000 mcg)

(Desired mcg) X kg. X 60 ÷ mcg/cc (in solution)

Example:- Give Dopamine 5 mcg/kg/min to a patient who
weights 65 kg.

5 X 65 X 60 ÷ (800 mg in 500 cc)

(5 mcg) X (65 kg) X 60 ÷ (800 mg ÷ 500 cc = 1.6 mg. X 1000)
= 1600 mcg
19500 ÷ 1600 = 12.18 cc

Example: Give Dopamine 2.5 mcg/kg/min to a patient who
weight 55 KG.

2.5 X 55 X 60 ÷ 1600
(2.5 mcg) X (55 kg) X 60 ÷ 1600 = 5.15 cc

TO DETERMINE MCG/KG/CC INFUSING:

Example: You have a patient that weighs 85 kg
who has a dopamine drip infusion at 8cc per
hour and you want to determine how many
mcg/kg/min the patient is receiving. The
dopamine is mixed at 1600 mcg per cc.

MCG/CC X RATE ÷ 60 ÷ KG

1600 X 8 ÷ 60 ÷ 85 = 2.5 mcg/kg/minute

Example : You have a patient that weighs 102 kg
who has a Dobutamine drip infusing at 12 cc
per hour and you want to determine how many
mcg/kg/min the patient is receiving. The
Dobutamine is mixed at 500 mg in 250 cc = 2000
mcg per cc.

(500 mg ÷ 250 = 2 X 1000 = 2000)

CONCLUSION

Inotropes are very effective drugs when
administered properly.
Patients receiving inotropes should be
monitored closely including blood pressure,
cardiac monitoring, intake and output, and
laboratory tests that have been ordered by the
physician.
Knowledge of desired effects and side effects is
critical to the administration of inotropes.

CONCLUSION
Cont…
 A thorough grasp of the pharmacology of
inotropes is crucial to understand the rationale
for drug therapy of heart failure.
 Inotropes continue to improve through scientific
research.
 Oral forms of inotropes are now being
investigated to manage congestive heart failure
at home.

BIBLIOGRAPHY

ACLS, Emergency Cardiovascular Care Program,
American Heart Association, 1997-1998, pp. 7.3-
7.4, 8.3-8.8.
Braunwald; Heart Disease, 1998, W. B. Saunders
Company, pp. 9468-9470, 9477-9481, 9492-9502.
Critical Care Nursing-Diagnosis and
Management, Second Edition. L. Thelan, et al.
Mosby-Year Book, Inc. 1994. pp 346-347
Physician’s Desk Reference, 1997, pp. 1116-1118.

Inotropesfs

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Inotropesfs