Milrinone, 1,6-dihydro-2-methyl-6-oxo-[3,4?-bipyridine]-5-carbonitrile, is a
positive inotropic cardiotonic agent with vasodilator properties that acts as
selective phosphodiesterase 3 inhibitor in cardiac and vascular smooth
muscle. Trade names of milrinone are Primacor, Corotrop, Corotrope, and
Milrila. Milrinone, an amrinone derivative, is 20 to 50 times more active
than amrinone and possesses reduced propensity to side effects. The use of
milrinone has created controversy in the medical as the result of increased
mortality rate among patients that received high amounts of milrinone in oral
form. Reaserch show that it can be benifitial for patients with severe
congestive heart failure when used as short-time intravenous therapy.
Milrinone properties, stability, as well as mechanism of action and synthesis
under laboratory and industry conditions have been described in this paper.
For industrial purposes milrinone is synthesized by condensation of
cyanoacetamide with 4-(dimethylamino)-3-(4-pyridinyl)-3-buten-2-one and
4-ethoxy-3-(4-pyridinyl)-3-buten-2-one in presence of a base, or by the
reaction of 1-(4-pyridinyl)- 2-propanone with ethoxymethylenmalononitrile or
4-alkoxy-3-(4-pyridinyl)-3-buten-2-one with malononitrile without the use of
external base. The starting compound for these syntheses is 4-picoline.
Alternative synthesis of milrinone starts from
2-methyl-3-(4-pyridylidiene)-1,1,5-tricyano-1,4-pentadiene-5-carboxamide and
2-methyl-6-oxo-1,6-dihydro-3,4?-bipyridine-5-carboxamide. Lastly, methods for
milrinone synthesis in laboratory, injection preparation and purification
have been summarized.