What are the doses of Dopamine, Dobutamine, and Norepinephrine in mcg/kg/min for a 60kg patient at 15ml/hr, 35ml/hr, and 50ml/hr respectively?

Calculating Vasopressor Doses in mcg/kg/min

Critical Information Missing

You must know the concentration of each medication to calculate the dose in mcg/kg/min. The infusion rates alone (15 mL/hr, 35 mL/hr, 50 mL/hr) cannot be converted to mcg/kg/min without knowing how much drug is in each milliliter of solution. 1

Standard Calculation Formula

The formula to convert infusion rate to dose is: 1

Dose (mcg/kg/min) = [Infusion rate (mL/hr) × Concentration (mcg/mL)] ÷ [Weight (kg) × 60 min/hr]

For your 60 kg patient, this simplifies to:

Dose (mcg/kg/min) = [Infusion rate (mL/hr) × Concentration (mcg/mL)] ÷ 3600

Standard Concentrations and Calculations

Dopamine at 15 mL/hr

• Standard concentration: 400 mg in 500 mL = 800 mcg/mL 2
• Calculation: (15 × 800) ÷ 3600 = 3.3 mcg/kg/min
• This falls in the low-dose range (2-5 mcg/kg/min), primarily causing dopaminergic effects 3

Dobutamine at 35 mL/hr

• Standard concentration: 250 mg in 250 mL = 1000 mcg/mL 2
• Calculation: (35 × 1000) ÷ 3600 = 9.7 mcg/kg/min
• This is within the typical therapeutic range of 2-20 mcg/kg/min 4, 2

Norepinephrine at 50 mL/hr

• Standard concentration: 4 mg in 250 mL = 16 mcg/mL 5
• Calculation: (50 × 16) ÷ 3600 = 0.22 mcg/kg/min
• This exceeds the typical starting dose of 0.1-0.5 mcg/kg/min but remains within therapeutic range 4, 5

Alternative Concentrations

If different concentrations are used at your institution:

Dopamine

• If 800 mg in 500 mL (1600 mcg/mL): 15 mL/hr = 6.7 mcg/kg/min 4
• If 200 mg in 250 mL (800 mcg/mL): 15 mL/hr = 3.3 mcg/kg/min 3

Dobutamine

• If 500 mg in 250 mL (2000 mcg/mL): 35 mL/hr = 19.4 mcg/kg/min 2
• If 250 mg in 500 mL (500 mcg/mL): 35 mL/hr = 4.9 mcg/kg/min 2

Norepinephrine

• If 8 mg in 250 mL (32 mcg/mL): 50 mL/hr = 0.44 mcg/kg/min 4
• If 4 mg in 500 mL (8 mcg/mL): 50 mL/hr = 0.11 mcg/kg/min 5

Clinical Context

These calculated doses assume standard concentrations and should be verified against your institution's preparation protocols. 1

• The dopamine dose of 3.3 mcg/kg/min provides primarily renal/mesenteric vasodilation with minimal cardiac effects 4, 3
• The dobutamine dose of 9.7 mcg/kg/min provides moderate inotropic support without excessive tachycardia 4, 2
• The norepinephrine dose of 0.22 mcg/kg/min provides vasopressor support appropriate for septic shock management 4, 5

Always confirm the actual drug concentration on the infusion bag label before making clinical decisions based on these calculations. 1