AMRINONE (INAMRINONE) ; used, Side effects, dose, pharmacodynamic & Mechanism of action.....

 AMRINONE (INAMRINONE) 

BRAND NAME:-AMICOR,CARDIOTONE 5mg/ml (as lactate) 20ml amp.

AMRINONE is also known as INAMRINONE ,is a chemically and pharmacologically distinct from digitalis and catecholamines. This bipyridine derivative is a selective phosphodiesterase 3 (PDE3) inhibitors.

It is a drug that may improve the prognosis in patients with congestive heart failure .

Pharmacodynamic :-

Amrinone is a positive inotropic cardiotonic with vasodilator properties, phosphodiesterase inhibitory activity, and the ability to stimulate calcium ion influx into the cardiac cell.

 Mechanism of action:-

It  is a chemically and pharmacologically distinct from digitalis and catecholamines. This bipyridine derivative is a selective phosphodiesterase 3 (PDE3) inhibitors. The PDE3 ISOENZYME is sepcific for intracellular degradation of cAMP in heart, blood vessels and bronchial smooth muscles. AMRINONE increases myocardial cAMP and transmembrane influx of Ca²+. It does not inhibits Na+K+ATPase, and its action is independent of tissue catecholamines as well as adrenergic receptors.

  The two most important actions of amrinone are positive inotropy and direct vasodilation : has been called an 'inodilator'  . Both preload and afterload on the heart is reduced. Compared to dobutamine , proportionately greater Decreases in systemic vascular resistance is noted.

 In CHF patients i.v. amrinone action starts in 5 min and lasts 2-3 hour's; elimination t½ is 2-4 hours . It increases cardiac index,left ventricular ejection fraction and Decreases peripheral vascular resistance,CVP, left ventricular end diastolic volume and pressure accompanied by mild tachycardia and slight fall in BP.

Used:- 

it's oral use in maintenance therapy of CHF has been abandoned, because efficacy was lost and mortality was increased in comparison to placebo, used in severe and refractory CHF, as additional drug to conventional therapy with digitalis, diuretics and vasodilators.

ADVERSE EFFECTS:- 

Thrombocytopenia is the most prominent and dose related side effects,but is mostly Transient and asymptomatic.

Nausea, vomiting, diarrhoea, abdominal pain, liver damage,fever and arrhythmias are the others.

DOSE:- 

0.5 mg/kg bolus injection followed by 5-10 ug/kg/min i.v. infusion (max. 10mg/kg in 24 hours). As directed by the physician.