Dobutamine vs Milrinone
Dobutamine has a faster mechanism action. It takes about 5-10 minutes. Milrinone takes about 4 to 6 hrs to take effect. Both drugs are pro-arrhythmic. However, in my experience milrinone is the most pro-arrhythmic drug known to me. You may have a slight drop in blood pressure with dobutamine but even more with milrinone. Dobutamine may increase your heart rate, increasing your oxygen demand.
Dobutamine: increases heart rate, increases your oxygen demand. (terrible for a weak or ischemic heart)
Slightly decreases your SVR. (it helps your heart to overcome or push against your afterload)
Increases your heart's contraction. Fast onset action and your body gets rid of it quite fast.
Milrinone: It does not affects your heart rate. Great for an ischemic heart.
Stronger vasodilator than dobutamine. It takes 4 to 6 hrs for onset of action and takes your body a longer time to get rid of it. used to help reduce pulmonary hypertension, super beneficial for the right side of your heart. Detrimental for patients in kidney failure.
Dopamine: It increases your afterload which can increased your heart workload and increased oxygen demand. However, I have seen a decrease in afterload with low dose dopamine.
I hope this helps.