Milrinone, commonly known and marketed as the drug Primacor, is a medication used in patients suffering from heart failure. Milrinone is a phosphodiesterase 3 inhibitor that works to increase the heart's contractility. Milrinone also works to vasodilate vessels which helps alleviate increased pressures (afterload) on the heart, thus improving its pumping action. Milrinone has been used in those suffering from heart failure for many years. There are receptors on cardiomyocytes called β-adrenergic receptors. These receptors are stimulated by molecules such as norepinephrine and epinephrine. Stimulation of these receptors causes a cascade of events ultimately leading to increase cyclic adenosine monophosphate (cAMP) within the cell. Cyclic adenosine monophosphate causes increase activation of protein kinase A (PKA).
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