Final answer:
Milrinone is a medication that increases heart contractility and improves cardiac output. It works by inhibiting an enzyme and promoting calcium release in cardiac cells. Milrinone has vasodilatory effects and is primarily excreted through the kidneys.
Step-by-step explanation:
Milrinone is a medication used to increase heart contractility and improve cardiac output in patients with heart failure. It works by inhibiting the enzyme phosphodiesterase III, which leads to increased levels of cyclic adenosine monophosphate (cAMP) in cardiac cells. This, in turn, promotes calcium release and enhances the contractility of the heart muscle.
Milrinone also has vasodilatory effects, meaning it relaxes and widens blood vessels, which can lower blood pressure. It can be used as an alternative to other pressors, such as dopamine or dobutamine, in the treatment of heart failure because it does not rely on adrenergic receptor stimulation to increase cardiac output.
Milrinone is primarily excreted through the kidneys, with approximately 50% of a dose being eliminated unchanged in the urine. It has a relatively short elimination half-life of around 2-3 hours.