Milrinone

Milrinone

Clinical data
AHFS/Drugs.com	Monograph
MedlinePlus	a601020
Pregnancy category	US: C (Risk not ruled out)
Routes of administration	IV only
ATC code	C01CE02 (WHO)
Legal status
Legal status	In general: ℞ (Prescription only)
Pharmacokinetic data
Bioavailability	100% (as IV bolus, infusion)
Protein binding	70 to 80%
Metabolism	Hepatic (12%)
Biological half-life	2.3 hours (mean, in CHF)
Excretion	Urine (85% as unchanged drug) within 24 hours
Identifiers
IUPAC name 2-Methyl-6-oxo-1,6-dihydro-3,4'-bipyridine-5-carbonitrile
CAS Number	78415-72-2 Y
PubChem CID	4197
IUPHAR/BPS	5225
DrugBank	DB00235 Y
ChemSpider	4052 Y
UNII	JU9YAX04C7
KEGG	D00417 Y
ChEBI	CHEBI:50693 Y
ChEMBL	CHEMBL189 Y
ECHA InfoCard	100.071.709
Chemical and physical data
Formula	C12H9N3O
Molar mass	211.219 g/mol
3D model (Jmol)	Interactive image
Density	1.344 g/cm3
Melting point	315 °C (599 °F)
Boiling point	449 °C (840 °F)
SMILES c1cnccc1-c2c(C)[nH]c(=O)c(C#N)c2
InChI InChI=1S/C12H9N3O/c1-8-11(9-2-4-14-5-3-9)6-10(7-13)12(16)15-8/h2-6H,1H3,(H,15,16) Y Key:PZRHRDRVRGEVNW-UHFFFAOYSA-N Y

Milrinone, commonly known and marketed under the brand name Primacor, is a medication used in patients who have heart failure. It is a phosphodiesterase 3 inhibitor that works to increase the heart's contractility and decrease pulmonary vascular resistance. Milrinone also works to vasodilate which helps alleviate increased pressures (afterload) on the heart, thus improving its pumping action. While it has been used in people with heart failure for many years, recent studies suggest that milrinone may exhibit some negative side effects that have caused some debate about its use clinically.

Overall, milrinone supports ventricular functioning of the heart by decreasing the degradation of cAMP and thus increasing phosphorylation levels of many components in the heart that contribute to contractility and heart rate. Milrinone use following cardiac surgery has been under some debate because of the potential increase risk of postoperative atrial arrhythmias. However, in the short term milrinone has been deemed beneficial to those experiencing heart failure and an effective therapy to maintain heart function following cardiac surgeries. There is no evidence of any long term beneficial effects on survival. In critically ill patients with evidence of cardiac dysfunction there is limited good quality evidence to recommend its use.

People experiencing some forms of heart failure have a significant decrease in the contractile ability of muscle cells in the heart (cardiomyocytes). This impaired contractility occurs through a number of mechanisms. Some of the main problems associated with decreased contractility in those with heart failure are issues arising from imbalances in the concentration of calcium. Calcium permits myosin and actin to interact which allows initiation of contraction within the cardiomyocytes. In those with heart failure there may be a decreased amount of calcium within the cardiomyocytes reducing the available calcium to initiate contraction. When contractility is decreased the amount of blood being pumped out of the heart into circulation is decreased as well. This reduction in cardiac output can cause many systemic implications such as fatigue, syncope and other issues associated with decreased blood flow to peripheral tissues.