If you load 0.3 mg/kg of ADRENALINE / NOR ADRENALINE / ISOPRENALINE in a 50 ml syringe then infusion @ 1 ml/hr of any of these drug will result in delivery of 0.1 μg/kg/min of the same
If you load 3units/kg of VASOPRESSIN in a 50 ml syringe, then infusion @ 1 ml/hr of any of these drug will result in delivery of 0.001 units/kg/min of the same
e.g. If your patient weighs 60 kg, and you want to start Dopamine @ 5μg/kg/min; you load 3x60=180mg of Dopamine and dilute it to 50 ml in a 50ml syringe. Now if u start the infusion @1ml/hr, it will deliver 1μg/kg/min of Dopamine. We want it to run @ 5μg/kg/min. So keep it at 5ml/hr.