Cardiotonics (Cardiac Glycosides) 173dose in given. In this condition, drugs like
verapamil is more effective.
Left Ventricular Failure
Digitalis is used in chronic pure, left
ventricular failure with hypertension and
ischemic heart disease.
OTHER POSITIVE INOTROPIC
DRUGS USED IN CHFBIPYRIDINE COMPOUNDS
AMRINONE
It is a relatively selective inhibitor of cyclic
GMP, cyclic AMP-PDE (phosphodiesterase)
type III family. It causes vasodilatation with
a consequent decrease in systemic vascular
resistance. It increases both the force of
contraction and velocity of relaxation of
cardiac muscles. It is administered IV 0.75
mg/kg/min as a bolus dose followed by 5-
10 μg/kg/min IV infusion and total dose not
to exceed 10 mg/kg.
Side effects include nausea, abdominal
pain, diarrhoea, fever, thrombocytopenia (tran-
sient and dose related) and hepatotoxicity.MILRINONE
It is relatively selective inhibitor of
peak III cyclic AMP phosphodiesterase
isoenzyme in cardiac and vascular
muscle. In patients with CHF, it produces
dose related and plasma concentration
related increase in the maximum rate of
increase of left ventricular pressure.
Milrinone has a direct inotropic and
direct arterial vasodilator activity. It is
administrated by IV infusion 0.50 mg/kg
over 10 min with a maximum daily dose
of 1.13 mg/kg.
Side effects include ventricular
arrhythmias, sustained ventricular tachycar-
dia, angina, ventricular fibrillation, head-
ache and hypokalemia.
Both the compounds are indicated in short
term management of CHF in patents unre-
sponsive to digitalis, diuretics or vasodilators.